Administration Guide

Red Hat Gluster Storage 3.5

Configuring and Managing Red Hat Gluster Storage

Red Hat Gluster Storage Documentation Team

Abstract

Red Hat Gluster Storage Administration Guide describes the configuration and management of Red Hat Gluster Storage for On-Premise.
Making open source more inclusive
Red Hat is committed to replacing problematic language in our code, documentation, and web properties. We are beginning with these four terms: master, slave, blacklist, and whitelist. Because of the enormity of this endeavor, these changes will be implemented gradually over several upcoming releases. For more details, see our CTO Chris Wright's message

Part I. Preface

Chapter 1. Preface

1.1. About Red Hat Gluster Storage

Red Hat Gluster Storage is a software-only, scale-out storage solution that provides flexible and agile unstructured data storage for the enterprise.
Red Hat Gluster Storage provides new opportunities to unify data storage and infrastructure, increase performance, and improve availability and manageability in order to meet a broader set of an organization’s storage challenges and needs.
The product can be installed and managed on-premises, or in a public cloud.

1.2. About glusterFS

glusterFS aggregates various storage servers over network interconnects into one large parallel network file system. Based on a stackable user space design, it delivers exceptional performance for diverse workloads and is a key building block of Red Hat Gluster Storage.
The POSIX compatible glusterFS servers, which use XFS file system format to store data on disks, can be accessed using industry-standard access protocols including Network File System (NFS) and Server Message Block (SMB) (also known as CIFS).

1.3. About On-premises Installation

Red Hat Gluster Storage for On-Premise allows physical storage to be utilized as a virtualized, scalable, and centrally managed pool of storage.
Red Hat Gluster Storage can be installed on commodity servers resulting in a powerful, massively scalable, and highly available NAS environment.

Part II. Overview

Chapter 2. Architecture and Concepts

This chapter provides an overview of Red Hat Gluster Storage architecture and Storage concepts.

2.1. Architecture

At the core of the Red Hat Gluster Storage design is a completely new method of architecting storage. The result is a system that has immense scalability, is highly resilient, and offers extraordinary performance.
In a scale-out system, one of the biggest challenges is keeping track of the logical and physical locations of data and metadata. Most distributed systems solve this problem by creating a metadata server to track the location of data and metadata. As traditional systems add more files, more servers, or more disks, the central metadata server becomes a performance bottleneck, as well as a central point of failure.
Unlike other traditional storage solutions, Red Hat Gluster Storage does not need a metadata server, and locates files algorithmically using an elastic hashing algorithm. This no-metadata server architecture ensures better performance, linear scalability, and reliability.
Red Hat Gluster Storage Architecture

Figure 2.1. Red Hat Gluster Storage Architecture

2.2. On-premises Architecture

Red Hat Gluster Storage for On-premises enables enterprises to treat physical storage as a virtualized, scalable, and centrally managed storage pool by using commodity storage hardware.
It supports multi-tenancy by partitioning users or groups into logical volumes on shared storage. It enables users to eliminate, decrease, or manage their dependence on high-cost, monolithic and difficult-to-deploy storage arrays.
You can add capacity in a matter of minutes across a wide variety of workloads without affecting performance. Storage can also be centrally managed across a variety of workloads, thus increasing storage efficiency.
Red Hat Gluster Storage for On-premises Architecture

Figure 2.2. Red Hat Gluster Storage for On-premises Architecture

Red Hat Gluster Storage for On-premises is based on glusterFS, an open source distributed file system with a modular, stackable design, and a unique no-metadata server architecture. This no-metadata server architecture ensures better performance, linear scalability, and reliability.

2.3. Storage Concepts

Following are the common terms relating to file systems and storage used throughout the Red Hat Gluster Storage Administration Guide.
Brick
The glusterFS basic unit of storage, represented by an export directory on a server in the trusted storage pool. A brick is expressed by combining a server with an export directory in the following format:
SERVER:EXPORT
For example:
myhostname:/exports/myexportdir/
Volume
A volume is a logical collection of bricks. Most of the Red Hat Gluster Storage management operations happen on the volume.
Translator
A translator connects to one or more subvolumes, does something with them, and offers a subvolume connection.
Subvolume
A brick after being processed by at least one translator.
Volfile
Volume (vol) files are configuration files that determine the behavior of your Red Hat Gluster Storage trusted storage pool. At a high level, GlusterFS has three entities, that is, Server, Client and Management daemon. Each of these entities have their own volume files. Volume files for servers and clients are generated by the management daemon upon creation of a volume.
Server and Client Vol files are located in /var/lib/glusterd/vols/VOLNAME directory. The management daemon vol file is named as glusterd.vol and is located in /etc/glusterfs/ directory.

Warning

You must not modify any vol file in /var/lib/glusterd manually as Red Hat does not support vol files that are not generated by the management daemon.
glusterd
glusterd is the glusterFS Management Service that must run on all servers in the trusted storage pool.
Cluster
A trusted pool of linked computers working together, resembling a single computing resource. In Red Hat Gluster Storage, a cluster is also referred to as a trusted storage pool.
Client
The machine that mounts a volume (this may also be a server).
File System
A method of storing and organizing computer files. A file system organizes files into a database for the storage, manipulation, and retrieval by the computer's operating system.
Source: Wikipedia
Distributed File System
A file system that allows multiple clients to concurrently access data which is spread across servers/bricks in a trusted storage pool. Data sharing among multiple locations is fundamental to all distributed file systems.
Virtual File System (VFS)
VFS is a kernel software layer that handles all system calls related to the standard Linux file system. It provides a common interface to several kinds of file systems.
POSIX
Portable Operating System Interface (for Unix) (POSIX) is the name of a family of related standards specified by the IEEE to define the application programming interface (API), as well as shell and utilities interfaces, for software that is compatible with variants of the UNIX operating system. Red Hat Gluster Storage exports a fully POSIX compatible file system.
Metadata
Metadata is data providing information about other pieces of data.
FUSE
Filesystem in User space (FUSE) is a loadable kernel module for Unix-like operating systems that lets non-privileged users create their own file systems without editing kernel code. This is achieved by running file system code in user space while the FUSE module provides only a "bridge" to the kernel interfaces.
Source: Wikipedia
Geo-Replication
Geo-replication provides a continuous, asynchronous, and incremental replication service from one site to another over Local Area Networks (LAN), Wide Area Networks (WAN), and the Internet.
N-way Replication
Local synchronous data replication that is typically deployed across campus or Amazon Web Services Availability Zones.
Petabyte
A petabyte is a unit of information equal to one quadrillion bytes, or 1000 terabytes. The unit symbol for the petabyte is PB. The prefix peta- (P) indicates a power of 1000:
1 PB = 1,000,000,000,000,000 B = 1000^5 B = 10^15 B.
The term "pebibyte" (PiB), using a binary prefix, is used for the corresponding power of 1024.
Source: Wikipedia
RAID
Redundant Array of Independent Disks (RAID) is a technology that provides increased storage reliability through redundancy. It combines multiple low-cost, less-reliable disk drives components into a logical unit where all drives in the array are interdependent.
RRDNS
Round Robin Domain Name Service (RRDNS) is a method to distribute load across application servers. RRDNS is implemented by creating multiple records with the same name and different IP addresses in the zone file of a DNS server.
Server
The machine (virtual or bare metal) that hosts the file system in which data is stored.
Block Storage
Block special files, or block devices, correspond to devices through which the system moves data in the form of blocks. These device nodes often represent addressable devices such as hard disks, CD-ROM drives, or memory regions. As of Red Hat Gluster Storage 3.4 and later, block storage supports only OpenShift Container Storage converged and independent mode use cases. Block storage can be created and configured for this use case by using the gluster-block command line tool. For more information, see Container-Native Storage for OpenShift Container Platform.
Scale-Up Storage
Increases the capacity of the storage device in a single dimension. For example, adding additional disk capacity in a trusted storage pool.
Scale-Out Storage
Increases the capability of a storage device in single dimension. For example, adding more systems of the same size, or adding servers to a trusted storage pool that increases CPU, disk capacity, and throughput for the trusted storage pool.
Trusted Storage Pool
A storage pool is a trusted network of storage servers. When you start the first server, the storage pool consists of only that server.
Namespace
An abstract container or environment that is created to hold a logical grouping of unique identifiers or symbols. Each Red Hat Gluster Storage trusted storage pool exposes a single namespace as a POSIX mount point which contains every file in the trusted storage pool.
User Space
Applications running in user space do not directly interact with hardware, instead using the kernel to moderate access. User space applications are generally more portable than applications in kernel space. glusterFS is a user space application.
Distributed Hash Table Terminology

Hashed subvolume
A Distributed Hash Table Translator subvolume to which the file or directory name is hashed to.
Cached subvolume
A Distributed Hash Table Translator subvolume where the file content is actually present. For directories, the concept of cached-subvolume is not relevant. It is loosely used to mean subvolumes which are not hashed-subvolume.
Linkto-file
For a newly created file, the hashed and cached subvolumes are the same. When directory entry operations like rename (which can change the name and hence hashed subvolume of the file) are performed on the file, instead of moving the entire data in the file to a new hashed subvolume, a file is created with the same name on the newly hashed subvolume. The purpose of this file is only to act as a pointer to the node where the data is present. In the extended attributes of this file, the name of the cached subvolume is stored. This file on the newly hashed-subvolume is called a linkto-file. The linkto file is relevant only for non-directory entities.
Directory Layout
The directory layout helps determine where files in a gluster volume are stored.
When a client creates or requests a file, the DHT translator hashes the file's path to create an integer. Each directory in a gluster subvolume holds files that have integers in a specific range, so the hash of any given file maps to a specific subvolume in the gluster volume. The directory layout determines which integer ranges are assigned to a given directory across all subvolumes.
Directory layouts are assigned when a directory is first created, and can be reassigned by running a rebalance operation on the volume. If a brick or subvolume is offline when a directory is created, it will not be part of the layout until after a rebalance is run.
You should rebalance a volume to recalculate its directory layout after bricks are added to the volume. See Section 11.11, “Rebalancing Volumes” for more information.
Fix Layout
A command that is executed during the rebalance process.
The rebalance process itself comprises of two stages:
  1. Fixes the layouts of directories to accommodate any subvolumes that are added or removed. It also heals the directories, checks whether the layout is non-contiguous, and persists the layout in extended attributes, if needed. It also ensures that the directories have the same attributes across all the subvolumes.
  2. Migrates the data from the cached-subvolume to the hashed-subvolume.

Part III. Configure and Verify

Chapter 3. Considerations for Red Hat Gluster Storage

3.1. Firewall and Port Access

Red Hat Gluster Storage requires access to a number of ports in order to work properly. Ensure that port access is available as indicated in Section 3.1.2, “Port Access Requirements”.

3.1.1. Configuring the Firewall

Firewall configuration tools differ between Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux 7.
For Red Hat Enterprise Linux 6, use the iptables command to open a port:
# iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 5667 -j ACCEPT
# service iptables save

Important

Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
For Red Hat Enterprise Linux 7, if default ports are not already in use by other services, it is usually simpler to add a service rather than open a port:
# firewall-cmd --zone=zone_name --add-service=glusterfs
# firewall-cmd --zone=zone_name --add-service=glusterfs --permanent
However, if the default ports are already in use, you can open a specific port with the following command:
# firewall-cmd --zone=zone_name --add-port=port/protocol
# firewall-cmd --zone=zone_name --add-port=port/protocol --permanent
For example:
# firewall-cmd --zone=public --add-port=5667/tcp
# firewall-cmd --zone=public --add-port=5667/tcp --permanent

3.1.2. Port Access Requirements

Table 3.1. Open the following ports on all storage servers

Connection sourceTCP PortsUDP PortsRecommended forUsed for
Any authorized network entity with a valid SSH key22-All configurationsRemote backup using geo-replication
Any authorized network entity; be cautious not to clash with other RPC services.111111All configurationsRPC port mapper and RPC bind
Any authorized SMB/CIFS client139 and 445137 and 138Sharing storage using SMB/CIFSSMB/CIFS protocol
Any authorized NFS clients20492049Sharing storage using Gluster NFS or NFS-GaneshaExports using NFS protocol
All servers in the Samba-CTDB cluster4379-Sharing storage using SMB and Gluster NFSCTDB
Any authorized network entity24007-All configurationsManagement processes using glusterd
Any authorized network entity55555-All configurations
Gluster events daemon
If you are upgrading from a previous version of Red Hat Gluster Storage to the latest version 3.5.4, the port used for glusterevents daemon should be modified to be in the ephemral range.
NFSv3 clients662662Sharing storage using NFS-Ganesha and Gluster NFSstatd
NFSv3 clients3280332803Sharing storage using NFS-Ganesha and Gluster NFSNLM protocol
NFSv3 clients sending mount requests-32769Sharing storage using Gluster NFSGluster NFS MOUNT protocol
NFSv3 clients sending mount requests2004820048Sharing storage using NFS-GaneshaNFS-Ganesha MOUNT protocol
NFS clients875875Sharing storage using NFS-GaneshaNFS-Ganesha RQUOTA protocol (fetching quota information)
Servers in pacemaker/corosync cluster2224-Sharing storage using NFS-Ganeshapcsd
Servers in pacemaker/corosync cluster3121-Sharing storage using NFS-Ganeshapacemaker_remote
Servers in pacemaker/corosync cluster-5404 and 5405Sharing storage using NFS-Ganeshacorosync
Servers in pacemaker/corosync cluster21064-Sharing storage using NFS-Ganeshadlm
Any authorized network entity49152 - 49664-All configurationsBrick communication ports. The total number of ports required depends on the number of bricks on the node. One port is required for each brick on the machine.
Gluster Clients1023 or 49152-Applicable when system ports are already being used in the machines.Communication between brick and client processes.

Table 3.2. Open the following ports on NFS-Ganesha and Gluster NFS storage clients

Connection sourceTCP PortsUDP PortsRecommended forUsed for
NFSv3 servers662662Sharing storage using NFS-Ganesha and Gluster NFSstatd
NFSv3 servers3280332803Sharing storage using NFS-Ganesha and Gluster NFSNLM protocol

3.2. Feature Compatibility Support

Red Hat Gluster Storage supports a number of features. Most features are supported with other features, but there are some exceptions. This section clearly identifies which features are supported and compatible with other features to help you in planning your Red Hat Gluster Storage deployment.

Note

Internet Protocol Version 6 (IPv6) support is available only for Red Hat Hyperconverged Infrastructure for Virtualization environments and not for Red Hat Gluster Storage standalone environments.
Features in the following table are supported from the specified version and later.

Table 3.3. Features supported by Red Hat Gluster Storage version

FeatureVersion
Arbiter bricks3.2
Bitrot detection3.1
Erasure coding3.1
Google Compute Engine3.1.3
Metadata caching3.2
Microsoft Azure3.1.3
NFS version 43.1
SELinux3.1
Sharding3.2.0
Snapshots3.0
Snapshots, cloning3.1.3
Snapshots, user-serviceable3.0.3
Tiering (Deprecated)3.1.2
Volume Shadow Copy (VSS)3.1.3

Table 3.4. Features supported by volume type

Volume TypeShardingTiering (Deprecated)QuotaSnapshotsGeo-RepBitrot
Arbitrated-ReplicatedYesNoYesYesYesYes
DistributedNoYesYesYesYesYes
Distributed-DispersedNoYesYesYesYesYes
Distributed-ReplicatedYesYesYesYesYesYes
ReplicatedYesYesYesYesYesYes
ShardedN/ANoNoNoYesNo
Tiered (Deprecated)NoN/ALimited[a]Limited[a]Limited[a]Limited[a]

Table 3.5. Features supported by client protocol

FeatureFUSEGluster-NFSNFS-GaneshaSMB
ArbiterYesYesYesYes
Bitrot detectionYesYesNoYes
dm-cacheYesYesYesYes
Encryption (TLS-SSL)YesYesYesYes
Erasure codingYesYesYesYes
Export subdirectoryYesYesYesN/A
Geo-replicationYesYesYesYes
Quota (Deprecated)

Warning

Using QUOTA feature is considered to be deprecated in Red Hat Gluster Storage 3.5.3. Red Hat no longer recommends to use this feature and does not support it on new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
YesYesYesYes
RDMA (Deprecated)

Warning

Using RDMA as a transport protocol is considered deprecated in Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support it on new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
YesNoNoNo
SnapshotsYesYesYesYes
Snapshot cloningYesYesYesYes
Tiering (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
YesYesN/AN/A

Chapter 4. Adding Servers to the Trusted Storage Pool

A storage pool is a network of storage servers.
When the first server starts, the storage pool consists of that server alone. Adding additional storage servers to the storage pool is achieved using the probe command from a running, trusted storage server.

Important

Before adding servers to the trusted storage pool, you must ensure that the ports specified in Chapter 3, Considerations for Red Hat Gluster Storage are open.
On Red Hat Enterprise Linux 7, enable the glusterFS firewall service in the active zones for runtime and permanent mode using the following commands:
To get a list of active zones, run the following command:
# firewall-cmd --get-active-zones
To allow the firewall service in the active zones, run the following commands:
# firewall-cmd --zone=zone_name --add-service=glusterfs
# firewall-cmd --zone=zone_name --add-service=glusterfs --permanent
For more information about using firewalls, see section Using Firewalls in the Red Hat Enterprise Linux 7 Security Guide: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Security_Guide/sec-Using_Firewalls.html.

Note

When any two gluster commands are executed concurrently on the same volume, the following error is displayed:
Another transaction is in progress.
This behavior in the Red Hat Gluster Storage prevents two or more commands from simultaneously modifying a volume configuration, potentially resulting in an inconsistent state. Such an implementation is common in environments with monitoring frameworks such as the Red Hat Gluster Storage Console, and Red Hat Enterprise Virtualization Manager. For example, in a four node Red Hat Gluster Storage Trusted Storage Pool, this message is observed when gluster volume status VOLNAME command is executed from two of the nodes simultaneously.

4.1. Adding Servers to the Trusted Storage Pool

The gluster peer probe [server] command is used to add servers to the trusted server pool.

Note

Probing a node from lower version to a higher version of Red Hat Gluster Storage node is not supported.

Adding Three Servers to a Trusted Storage Pool

Create a trusted storage pool consisting of three storage servers, which comprise a volume.

Prerequisites

  • The glusterd service must be running on all storage servers requiring addition to the trusted storage pool. See Chapter 22, Starting and Stopping the glusterd service for service start and stop commands.
  • Server1, the trusted storage server, is started.
  • The host names of the target servers must be resolvable by DNS.
  1. Run gluster peer probe [server] from Server 1 to add additional servers to the trusted storage pool.

    Note

    • Self-probing Server1 will result in an error because it is part of the trusted storage pool by default.
    • All the servers in the Trusted Storage Pool must have RDMA devices if either RDMA or RDMA,TCP volumes are created in the storage pool. The peer probe must be performed using IP/hostname assigned to the RDMA device.
    # gluster peer probe server2
    Probe successful
    
    # gluster peer probe server3
    Probe successful
    
    # gluster peer probe server4
    Probe successful
  2. Verify the peer status from all servers using the following command:
    # gluster peer status
      Number of Peers: 3
    
      Hostname: server2
      Uuid: 5e987bda-16dd-43c2-835b-08b7d55e94e5
      State: Peer in Cluster (Connected)
    
      Hostname: server3
      Uuid: 1e0ca3aa-9ef7-4f66-8f15-cbc348f29ff7
      State: Peer in Cluster (Connected)
    
      Hostname: server4
      Uuid: 3e0caba-9df7-4f66-8e5d-cbc348f29ff7
      State: Peer in Cluster (Connected)

Important

If the existing trusted storage pool has a geo-replication session, then after adding the new server to the trusted storage pool, perform the steps listed at Section 10.6, “Starting Geo-replication on a Newly Added Brick, Node, or Volume”.

Note

Verify that time is synchronized on all Gluster nodes by using the following command:
# for peer in `gluster peer status | grep Hostname | awk -F':' '{print $2}' | awk '{print $1}'`; do clockdiff $peer; done

4.2. Removing Servers from the Trusted Storage Pool

Warning

Before detaching a peer from the trusted storage pool, make sure that the clients are not using the node. If backup servers were not set at mount time using the backup-volfile-servers option, remount the volume on the client using the IP address or FQDN of another server in the trusted storage pool to avoid inconsistencies.
Run gluster peer detach server to remove a server from the storage pool.

Removing One Server from the Trusted Storage Pool

Remove one server from the Trusted Storage Pool, and check the peer status of the storage pool.

Prerequisites

  1. Run gluster peer detach [server] to remove the server from the trusted storage pool.
    # gluster peer detach (server)
    All clients mounted through the peer which is getting detached needs to be remounted, using one of the other active peers in the trusted storage pool, this ensures that the client gets notification on any changes done on the gluster configuration and if the same has been done do you want to proceed? (y/n) y
    peer detach: success
  2. Verify the peer status from all servers using the following command:
    # gluster peer status
    Number of Peers: 2
    
    Hostname: server2
    Uuid: 5e987bda-16dd-43c2-835b-08b7d55e94e5
    State: Peer in Cluster (Connected)
    
    Hostname: server3
    Uuid: 1e0ca3aa-9ef7-4f66-8f15-cbc348f29ff7
    

Chapter 5. Setting Up Storage Volumes

A Red Hat Gluster Storage volume is a logical collection of bricks, where each brick is an export directory on a server in the trusted storage pool. Most of the Red Hat Gluster Storage Server management operations are performed on the volume. For a detailed information about configuring Red Hat Gluster Storage for enhancing performance see, Chapter 19, Tuning for Performance

Warning

Red Hat does not support writing data directly into the bricks. Read and write data only through the Native Client, or through NFS or SMB mounts.

Note

Red Hat Gluster Storage supports IP over Infiniband (IPoIB). Install Infiniband packages on all Red Hat Gluster Storage servers and clients to support this feature. Run the yum groupinstall "Infiniband Support" to install Infiniband packages.

Volume Types

Distributed
Distributes files across bricks in the volume.
Use this volume type where scaling and redundancy requirements are not important, or provided by other hardware or software layers.
See Section 5.4, “Creating Distributed Volumes” for additional information about this volume type.
Replicated
Replicates files across bricks in the volume.
Use this volume type in environments where high-availability and high-reliability are critical.
See Section 5.5, “Creating Replicated Volumes” for additional information about this volume type.
Distributed Replicated
Distributes files across replicated bricks in the volume.
Use this volume type in environments where high-reliability and scalability are critical. This volume type offers improved read performance in most environments.
See Section 5.6, “Creating Distributed Replicated Volumes” for additional information about this volume type.
Arbitrated Replicated
Replicates files across two bricks in a replica set, and replicates only metadata to the third brick.
Use this volume type in environments where consistency is critical, but underlying storage space is at a premium.
See Section 5.7, “Creating Arbitrated Replicated Volumes” for additional information about this volume type.
Dispersed
Disperses the file's data across the bricks in the volume.
Use this volume type where you need a configurable level of reliability with a minimum space waste.
See Section 5.8, “Creating Dispersed Volumes” for additional information about this volume type.
Distributed Dispersed
Distributes file's data across the dispersed sub-volume.
Use this volume type where you need a configurable level of reliability with a minimum space waste.
See Section 5.9, “Creating Distributed Dispersed Volumes” for additional information about this volume type.

5.1. Setting up Gluster Storage Volumes using gdeploy

The gdeploy tool automates the process of creating, formatting, and mounting bricks. With gdeploy, the manual steps listed between Section 5.4 Formatting and Mounting Bricks and Section 5.10 Creating Distributed Dispersed Volumes are automated.
When setting-up a new trusted storage pool, gdeploy could be the preferred choice of trusted storage pool set up, as manually executing numerous commands can be error prone.
The advantages of using gdeploy to automate brick creation are as follows:
  • Setting-up the backend on several machines can be done from one's laptop/desktop. This saves time and scales up well when the number of nodes in the trusted storage pool increase.
  • Flexibility in choosing the drives to configure. (sd, vd, ...).
  • Flexibility in naming the logical volumes (LV) and volume groups (VG).

5.1.1. Getting Started

Prerequisites

  1. Generate the passphrase-less SSH keys for the nodes which are going to be part of the trusted storage pool by running the following command:
    # ssh-keygen -t rsa -N ''
  2. Set up key-based SSH authentication access between the gdeploy controller and servers by running the following command:
    # ssh-copy-id -i root@server

    Note

    If you are using a Red Hat Gluster Storage node as the deployment node and not an external node, then the key-based SSH authentication must be set up for the Red Hat Gluster Storage node from where the installation is performed.
  3. Enable the repository required to install Ansible by running the following command:
    For Red Hat Enterprise Linux 8
    # subscription-manager repos --enable=ansible-2-for-rhel-8-x86_64-rpms
    For Red Hat Enterprise Linux 7
    # subscription-manager repos --enable=rhel-7-server-ansible-2-rpms
  4. Install ansible by executing the following command:
    # yum install ansible
  5. You must also ensure the following:
    • Devices should be raw and unused
    • Default system locale must be set to en_US
      For information on system locale, refer to the Setting the System Locale of the Red Hat Enterprise Linux 7 System Administrator's Guide.
    • For multiple devices, use multiple volume groups, thinpool, and thinvol in the gdeploy configuration file
gdeploy can be used to deploy Red Hat Gluster Storage in two ways:
  • Using a node in a trusted storage pool
  • Using a machine outside the trusted storage pool
Using a node in a cluster

The gdeploy package is bundled as part of the initial installation of Red Hat Gluster Storage.

Using a machine outside the trusted storage pool

You must ensure that the Red Hat Gluster Storage is subscribed to the required channels. For more information see, Subscribing to the Red Hat Gluster Storage Server Channels in the Red Hat Gluster Storage 3.5 Installation Guide.

Execute the following command to install gdeploy:
# yum install gdeploy
For more information on installing gdeploy see, Installing Ansible to Support Gdeploy section in the Red Hat Gluster Storage 3.5 Installation Guide.

5.1.2. Setting up a Trusted Storage Pool

Creating a trusted storage pool is a tedious task and becomes more tedious as the nodes in the trusted storage pool grow. With gdeploy, just a configuration file can be used to set up a trusted storage pool. When gdeploy is installed, a sample configuration file will be created at:
/usr/share/doc/gdeploy/examples/gluster.conf.sample

Note

The trusted storage pool can be created either by performing each tasks, such as, setting up a backend, creating a volume, and mounting volumes independently or summed up as a single configuration.
For example, for a basic trusted storage pool of a 3 x 3 replicated volume the configuration details in the configuration file will be as follows:
3x3-volume-create.conf:
#
# Usage:
#       gdeploy -c 3x3-volume-create.conf
#
# This does backend setup first and then create the volume using the
# setup bricks.
#
#

[hosts]
10.70.46.13
10.70.46.17
10.70.46.21


# Common backend setup for 2 of the hosts.
[backend-setup]
devices=sdb,sdc,sdd
vgs=vg1,vg2,vg3
pools=pool1,pool2,pool3
lvs=lv1,lv2,lv3
mountpoints=/rhgs/brick1,/rhgs/brick2,/rhgs/brick3
brick_dirs=/rhgs/brick1/b1,/rhgs/brick2/b2,/rhgs/brick3/b3

# If backend-setup is different for each host
# [backend-setup:10.70.46.13]
# devices=sdb
# brick_dirs=/rhgs/brick1
#
# [backend-setup:10.70.46.17]
# devices=sda,sdb,sdc
# brick_dirs=/rhgs/brick{1,2,3}
#

[volume]
action=create
volname=sample_volname
replica=yes
replica_count=3
force=yes


[clients]
action=mount
volname=sample_volname
hosts=10.70.46.15
fstype=glusterfs
client_mount_points=/mnt/gluster
With this configuration a 3 x 3 replica trusted storage pool with the given IP addresses and backend device as /dev/sdb, /dev/sdc, /dev/sdd with the volume name as sample_volname will be created.
For more information on possible values, see Section 5.1.7, “Configuration File”
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf

Note

You can create a new configuration file by referencing the template file available at /usr/share/doc/gdeploy/examples/gluster.conf.sample. To invoke the new configuration file, run gdeploy -c /path_to_file/config.txt command.
To only setup the backend see, Section 5.1.3, “Setting up the Backend ”
To only create a volume see, Section 5.1.4, “Creating Volumes”
To only mount clients see, Section 5.1.5, “Mounting Clients”

5.1.3. Setting up the Backend

In order to setup a Gluster Storage volume, the LVM thin-p must be set up on the storage disks. If the number of machines in the trusted storage pool is huge, these tasks takes a long time, as the number of commands involved are huge and error prone if not cautious. With gdeploy, just a configuration file can be used to set up a backend. The backend is setup at the time of setting up a fresh trusted storage pool, which requires bricks to be setup before creating a volume. When gdeploy is installed, a sample configuration file will be created at:
/usr/share/doc/gdeploy/examples/gluster.conf.sample
A backend can be setup in two ways:
  • Using the [backend-setup] module
  • Creating Physical Volume (PV), Volume Group (VG), and Logical Volume (LV) individually

Note

For Red Hat Enterprise Linux 6, the xfsprogs package must be installed before setting up the backend bricks using gdeploy.

Important

Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide

5.1.3.1. Using the [backend-setup] Module

Backend setup can be done on specific machines or on all the machines. The backend-setup module internally creates PV, VG, and LV and mounts the device. Thin-p logical volumes are created as per the performance recommendations by Red Hat.
The backend can be setup based on the requirement, such as:
  • Generic
  • Specific
Generic

If the disk names are uniform across the machines then backend setup can be written as below. The backend is setup for all the hosts in the `hosts’ section.

For more information on possible values, see Section 5.1.7, “Configuration File”
Example configuration file: Backend-setup-generic.conf
#
# Usage:
#       gdeploy -c backend-setup-generic.conf
#
# This configuration creates backend for GlusterFS clusters
#

[hosts]
10.70.46.130
10.70.46.32
10.70.46.110
10.70.46.77

# Backend setup for all the nodes in the `hosts' section. This will create
# PV, VG, and LV with gdeploy generated names.
[backend-setup]
devices=vdb
Specific

If the disks names vary across the machines in the cluster then backend setup can be written for specific machines with specific disk names. gdeploy is quite flexible in allowing to do host specific setup in a single configuration file.

For more information on possible values, see Section 5.1.7, “Configuration File”
Example configuration file: backend-setup-hostwise.conf
#
# Usage:
#       gdeploy -c backend-setup-hostwise.conf
#
# This configuration creates backend for GlusterFS clusters
#

[hosts]
10.70.46.130
10.70.46.32
10.70.46.110
10.70.46.77

# Backend setup for 10.70.46.77 with default gdeploy generated names for
# Volume Groups and Logical Volumes. Volume names will be GLUSTER_vg1,
# GLUSTER_vg2...
[backend-setup:10.70.46.77]
devices=vda,vdb

# Backend setup for remaining 3 hosts in the `hosts' section with custom names
# for Volumes Groups and Logical Volumes.
[backend-setup:10.70.46.{130,32,110}]
devices=vdb,vdc,vdd
vgs=vg1,vg2,vg3
pools=pool1,pool2,pool3
lvs=lv1,lv2,lv3
mountpoints=/rhgs/brick1,/rhgs/brick2,/rhgs/brick3
brick_dirs=/rhgs/brick1/b1,/rhgs/brick2/b2,/rhgs/brick3/b3

5.1.3.2. Creating Backend by Setting up PV, VG, and LV

If the user needs more control over setting up the backend, then pv, vg, and lv can be created individually. LV module provides flexibility to create more than one LV on a VG. For example, the `backend-setup’ module setups up a thin-pool by default and applies default performance recommendations. However, if the user has a different use case which demands more than one LV, and a combination of thin and thick pools then `backend-setup’ is of no help. The user can use PV, VG, and LV modules to achieve this.
For more information on possible values, see Section 5.1.7, “Configuration File”
The below example shows how to create four logical volumes on a single volume group. The examples shows a mix of thin and thickpool LV creation.
[hosts]
10.70.46.130
10.70.46.32

[pv]
action=create
devices=vdb

[vg1]
action=create
vgname=RHS_vg1
pvname=vdb

[lv1]
action=create
vgname=RHS_vg1
lvname=engine_lv
lvtype=thick
size=10GB
mount=/rhgs/brick1

[lv2]
action=create
vgname=RHS_vg1
poolname=lvthinpool
lvtype=thinpool
poolmetadatasize=200MB
chunksize=1024k
size=30GB

[lv3]
action=create
lvname=lv_vmaddldisks
poolname=lvthinpool
vgname=RHS_vg1
lvtype=thinlv
mount=/rhgs/brick2
virtualsize=9GB

[lv4]
action=create
lvname=lv_vmrootdisks
poolname=lvthinpool
vgname=RHS_vg1
size=19GB
lvtype=thinlv
mount=/rhgs/brick3
virtualsize=19GB
Example to extend an existing VG:
#
# Extends a given given VG. pvname and vgname is mandatory, in this example the
# vg `RHS_vg1' is extended by adding pv, vdd. If the pv is not alreay present, it
# is created by gdeploy.
#
[hosts]
10.70.46.130
10.70.46.32

[vg2]
action=extend
vgname=RHS_vg1
pvname=vdd

5.1.4. Creating Volumes

Setting up volume involves writing long commands by choosing the hostname/IP and brick order carefully and this could be error prone. gdeploy helps in simplifying this task. When gdeploy is installed, a sample configuration file will be created at:
/usr/share/doc/gdeploy/examples/gluster.conf.sample
For example, for a basic trusted storage pool of a 4 x 3 replicate volume the configuration details in the configuration file will be as follows:
[hosts]
10.0.0.1
10.0.0.2
10.0.0.3
10.0.0.4

[volume]
action=create
volname=glustervol
transport=tcp,rdma
replica=yes
replica_count=3
brick_dirs=/glus/brick1/b1,/glus/brick1/b1,/glus/brick1/b1
force=yes
For more information on possible values, see Section 5.1.7, “Configuration File”
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf
Creating Multiple Volumes

Note

Support of creating multiple volumes only from gdeploy 2.0, please check your gdeploy version before trying this configuration.
While creating multiple volumes in a single configuration, the [volume] modules should be numbered. For example, if there are two volumes they will be numbered [volume1], [volume2]
vol-create.conf
[hosts]
10.70.46.130
10.70.46.32
10.70.46.16

[backend-setup]
devices=vdb,vdc,vdd,vde
mountpoints=/mnt/data{1-6}
brick_dirs=/mnt/data1/1,/mnt/data2/2,/mnt/data3/3,/mnt/data4/4,/mnt/data5/5,/mnt/data6/6

[volume1]
action=create
volname=vol-one
transport=tcp
replica=yes
replica_count=3
brick_dirs=/mnt/data1/1,/mnt/data2/2,/mnt/data5/5

[volume2]
action=create
volname=vol-two
transport=tcp
replica=yes
replica_count=3
brick_dirs=/mnt/data3/3,/mnt/data4/4,/mnt/data6/6
With gdeploy 2.0, a volume can be created with multiple volume options set. Number of keys should match number of values.
[hosts]
10.70.46.130
10.70.46.32
10.70.46.16

[backend-setup]
devices=vdb,vdc
mountpoints=/mnt/data{1-6}

[volume1]
action=create
volname=vol-one
transport=tcp
replica=yes
replica_count=3
key=group,storage.owner-uid,storage.owner-gid,features.shard,features.shard-block-size,performance.low-prio-threads,cluster.data-self-heal-algorithm
value=virt,36,36,on,512MB,32,full
brick_dirs=/mnt/data1/1,/mnt/data3/3,/mnt/data5/5

[volume2]
action=create
volname=vol-two
transport=tcp
replica=yes
key=group,storage.owner-uid,storage.owner-gid,features.shard,features.shard-block-size,performance.low-prio-threads,cluster.data-self-heal-algorithm
value=virt,36,36,on,512MB,32,full
replica_count=3
brick_dirs=/mnt/data2/2,/mnt/data4/4,/mnt/data6/6
The above configuration will create two volumes with multiple volume options set.

5.1.5. Mounting Clients

When mounting clients, instead of logging into every client which has to be mounted, gdeploy can be used to mount clients remotely. When gdeploy is installed, a sample configuration file will be created at:
/usr/share/doc/gdeploy/examples/gluster.conf.sample
Following is an example of the modifications to the configuration file in order to mount clients:
[clients]
action=mount
hosts=10.70.46.159
fstype=glusterfs
client_mount_points=/mnt/gluster
volname=10.0.0.1:glustervol

Note

If the file system type (fstype) is NFS, then mention it as nfs-version. The default version is 3.
For more information on possible values, see Section 5.1.7, “Configuration File”
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf

5.1.6. Configuring a Volume

The volumes can be configured using the configuration file. The volumes can be configured remotely using the configuration file without having to log into the trusted storage pool. For more information regarding the sections and options in the configuration file, see Section 5.1.7, “Configuration File”

5.1.6.1. Adding and Removing a Brick

The configuration file can be modified to add or remove a brick:
Adding a Brick

Modify the [volume] section in the configuration file to add a brick. For example:

[volume]
action=add-brick
volname=10.0.0.1:glustervol
bricks=10.0.0.1:/rhgs/new_brick
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf
Removing a Brick

Modify the [volume] section in the configuration file to remove a brick. For example:

[volume]
action=remove-brick
volname=10.0.0.1:glustervol
bricks=10.0.0.2:/rhgs/brick
state=commit
Other options for state are stop, start, and force.
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf
For more information on possible values, see Section 5.1.7, “Configuration File”

5.1.6.2. Rebalancing a Volume

Modify the [volume] section in the configuration file to rebalance a volume. For example:
[volume]
action=rebalance
volname=10.70.46.13:glustervol
state=start
Other options for state are stop, and fix-layout.
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf
For more information on possible values, see Section 5.1.7, “Configuration File”

5.1.6.3. Starting, Stopping, or Deleting a Volume

The configuration file can be modified to start, stop, or delete a volume:
Starting a Volume

Modify the [volume] section in the configuration file to start a volume. For example:

[volume]
action=start
volname=10.0.0.1:glustervol
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf
Stopping a Volume

Modify the [volume] section in the configuration file to start a volume. For example:

[volume]
action=stop
volname=10.0.0.1:glustervol
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf
Deleting a Volume

Modify the [volume] section in the configuration file to start a volume. For example:

[volume]
action=delete
volname=10.70.46.13:glustervol
After modifying the configuration file, invoke the configuration using the command:
# gdeploy -c txt.conf
For more information on possible values, see Section 5.1.7, “Configuration File”

5.1.7. Configuration File

The configuration file includes the various options that can be used to change the settings for gdeploy. The following options are currently supported:
  • [hosts]
  • [devices]
  • [disktype]
  • [diskcount]
  • [stripesize]
  • [vgs]
  • [pools]
  • [lvs]
  • [mountpoints]
  • [peer]
  • [clients]
  • [volume]
  • [backend-setup]
  • [pv]
  • [vg]
  • [lv]
  • [RH-subscription]
  • [yum]
  • [shell]
  • [update-file]
  • [service]
  • [script]
  • [firewalld]
  • [geo-replication]
The options are briefly explained in the following list:
  • hosts

    This is a mandatory section which contains the IP address or hostname of the machines in the trusted storage pool. Each hostname or IP address should be listed in a separate line.

    For example:
    [hosts]
    10.0.0.1
    10.0.0.2
  • devices

    This is a generic section and is applicable to all the hosts listed in the [hosts] section. However, if sections of hosts such as the [hostname] or [IP-address] is present, then the data in the generic sections like [devices] is ignored. Host specific data take precedence. This is an optional section.

    For example:
    [devices]
    /dev/sda
    /dev/sdb

    Note

    When configuring the backend setup, the devices should be either listed in this section or in the host specific section.
  • disktype

    This section specifies the disk configuration that is used while setting up the backend. gdeploy supports RAID 10, RAID 6, RAID 5, and JBOD configurations. This is an optional section and if the field is left empty, JBOD is taken as the default configuration. Valid values for this field are raid10, raid6, raid5, and jbod.

    For example:
    [disktype]
    raid6
  • diskcount

    This section specifies the number of data disks in the setup. This is a mandatory field if a RAID disk type is specified under [disktype]. If the [disktype] is JBOD the [diskcount] value is ignored. This parameter is host specific.

    For example:
    [diskcount]
    10
  • stripesize

    This section specifies the stripe_unit size in KB.

    Case 1: This field is not necessary if the [disktype] is JBOD, and any given value will be ignored.
    Case 2: This is a mandatory field if [disktype] is specified as RAID 5 or RAID 6.
    For [disktype] RAID 10, the default value is taken as 256KB. Red Hat does not recommend changing this value. If you specify any other value the following warning is displayed:
    "Warning: We recommend a stripe unit size of 256KB for RAID 10"

    Note

    Do not add any suffixes like K, KB, M, etc. This parameter is host specific and can be added in the hosts section.
    For example:
    [stripesize]
    128
  • vgs

    This section is deprecated in gdeploy 2.0. Please see [backend-setup] for more details for gdeploy 2.0. This section specifies the volume group names for the devices listed in [devices]. The number of volume groups in the [vgs] section should match the one in [devices]. If the volume group names are missing, the volume groups will be named as GLUSTER_vg{1, 2, 3, ...} as default.

    For example:
    [vgs]
    CUSTOM_vg1
    CUSTOM_vg2
  • pools

    This section is deprecated in gdeploy 2.0. Please see [backend-setup] for more details for gdeploy 2.0. This section specifies the pool names for the volume groups specified in the [vgs] section. The number of pools listed in the [pools] section should match the number of volume groups in the [vgs] section. If the pool names are missing, the pools will be named as GLUSTER_pool{1, 2, 3, ...}.

    For example:
    [pools]
    CUSTOM_pool1
    CUSTOM_pool2
  • lvs

    This section is deprecated in gdeploy 2.0. Please see [backend-setup] for more details for gdeploy 2.0. This section provides the logical volume names for the volume groups specified in [vgs]. The number of logical volumes listed in the [lvs] section should match the number of volume groups listed in [vgs]. If the logical volume names are missing, it is named as GLUSTER_lv{1, 2, 3, ...}.

    For example:
    [lvs]
    CUSTOM_lv1
    CUSTOM_lv2
  • mountpoints

    This section is deprecated in gdeploy 2.0. Please see [backend-setup] for more details for gdeploy 2.0. This section specifies the brick mount points for the logical volumes. The number of mount points should match the number of logical volumes specified in [lvs] If the mount points are missing, the mount points will be names as /gluster/brick{1, 2, 3…}.

    For example:
    [mountpoints]
    /rhgs/brick1
    /rhgs/brick2
  • peer

    This section specifies the configurations for the Trusted Storage Pool management (TSP). This section helps in making all the hosts specified in the [hosts] section to either probe each other to create the trusted storage pool or detach all of them from the trusted storage pool. The only option in this section is the option names 'action' which can have it's values to be either probe or detach.

    For example:
    [peer]
    action=probe
  • clients

    This section specifies the client hosts and client_mount_points to mount the gluster storage volume created. The 'action' option is to be specified for the framework to determine the action that has to be performed. The options are 'mount' and 'unmount'. The Client hosts field is mandatory. If the mount points are not specified, default will be taken as /mnt/gluster for all the hosts.

    The option fstype specifies how the gluster volume is to be mounted. Default is glusterfs (FUSE mount). The volume can also be mounted as NFS. Each client can have different types of volume mount, which has to be specified with a comma separated. The following fields are included:
    * action
    * hosts
    * fstype
    * client_mount_points
    For example:
    [clients]
    action=mount
    hosts=10.0.0.10
    fstype=nfs
    options=vers=3
    client_mount_points=/mnt/rhs
  • volume

    The section specifies the configuration options for the volume. The following fields are included in this section:

    * action
    * volname
    * transport
    * replica
    * replica_count
    * disperse
    * disperse_count
    * redundancy_count
    * force
    • action

      This option specifies what action must be performed in the volume. The choices can be [create, delete, add-brick, remove-brick].

      create: This choice is used to create a volume.
      delete: If the delete choice is used, all the options other than 'volname' will be ignored.
      add-brick or remove-brick: If the add-brick or remove-brick is chosen, extra option bricks with a comma separated list of brick names(in the format <hostname>:<brick path> should be provided. In case of remove-brick, state option should also be provided specifying the state of the volume after brick removal.
    • volname

      This option specifies the volume name. Default name is glustervol

      Note

      • In case of a volume operation, the 'hosts' section can be omitted, provided volname is in the format <hostname>:<volname>, where hostname is the hostname / IP of one of the nodes in the cluster
      • Only single volume creation/deletion/configuration is supported.
    • transport

      This option specifies the transport type. Default is tcp. Options are tcp or rdma (Deprecated) or tcp,rdma.

    • replica

      This option will specify if the volume should be of type replica. options are yes and no. Default is no. If 'replica' is provided as yes, the 'replica_count' should be provided.

    • disperse

      This option specifies if the volume should be of type disperse. Options are yes and no. Default is no.

    • disperse_count

      This field is optional even if 'disperse' is yes. If not specified, the number of bricks specified in the command line is taken as the disperse_count value.

    • redundancy_count

      If this value is not specified, and if 'disperse' is yes, it's default value is computed so that it generates an optimal configuration.

    • force

      This is an optional field and can be used during volume creation to forcefully create the volume.

    For example:
    [volname]
    action=create
    volname=glustervol
    transport=tcp,rdma
    replica=yes
    replica_count=3
    force=yes
  • backend-setup

    Available in gdeploy 2.0. This section sets up the backend for using with GlusterFS volume. If more than one backend-setup has to be done, they can be done by numbering the section like [backend-setup1], [backend-setup2], ...

    backend-setup section supports the following variables:
    • devices: This replaces the [pvs] section in gdeploy 1.x. devices variable lists the raw disks which should be used for backend setup. For example:
      [backend-setup]
      devices=sda,sdb,sdc
      This is a mandatory field.
    • dalign:
      The Logical Volume Manager can use a portion of the physical volume for storing its metadata while the rest is used as the data portion. Align the I/O at the Logical Volume Manager (LVM) layer using the dalign option while creating the physical volume. For example:
      [backend-setup]
      devices=sdb,sdc,sdd,sde
      dalign=256k
      For JBOD, use an alignment value of 256K. For hardware RAID, the alignment value should be obtained by multiplying the RAID stripe unit size with the number of data disks. If 12 disks are used in a RAID 6 configuration, the number of data disks is 10; on the other hand, if 12 disks are used in a RAID 10 configuration, the number of data disks is 6.
      The following example is appropriate for 12 disks in a RAID 6 configuration with a stripe unit size of 128 KiB:
      [backend-setup]
      devices=sdb,sdc,sdd,sde
      dalign=1280k
      The following example is appropriate for 12 disks in a RAID 10 configuration with a stripe unit size of 256 KiB:
      [backend-setup]
      devices=sdb,sdc,sdd,sde
      dalign=1536k
      To view the previously configured physical volume settings for the dalign option, run the pvs -o +pe_start device command. For example:
      # pvs -o +pe_start /dev/sdb
      PV         VG   Fmt  Attr PSize PFree 1st PE
      /dev/sdb        lvm2 a--  9.09t 9.09t   1.25m
      You can also set the dalign option in the PV section.
    • vgs: This is an optional variable. This variable replaces the [vgs] section in gdeploy 1.x. vgs variable lists the names to be used while creating volume groups. The number of VG names should match the number of devices or should be left blank. gdeploy will generate names for the VGs. For example:
      [backend-setup]
      devices=sda,sdb,sdc
      vgs=custom_vg1,custom_vg2,custom_vg3
      A pattern can be provided for the vgs like custom_vg{1..3}, this will create three vgs.
      [backend-setup]
      devices=sda,sdb,sdc
      vgs=custom_vg{1..3}
    • pools: This is an optional variable. The variable replaces the [pools] section in gdeploy 1.x. pools lists the thin pool names for the volume.
      [backend-setup]
      devices=sda,sdb,sdc
      vgs=custom_vg1,custom_vg2,custom_vg3
      pools=custom_pool1,custom_pool2,custom_pool3
      Similar to vg, pattern can be provided for thin pool names. For example custom_pool{1..3}
    • lvs: This is an optional variable. This variable replaces the [lvs] section in gdeploy 1.x. lvs lists the logical volume name for the volume.
      [backend-setup]
      devices=sda,sdb,sdc
      vgs=custom_vg1,custom_vg2,custom_vg3
      pools=custom_pool1,custom_pool2,custom_pool3
      lvs=custom_lv1,custom_lv2,custom_lv3
      Patterns for LV can be provided similar to vg. For example custom_lv{1..3}.
    • mountpoints: This variable deprecates the [mountpoints] section in gdeploy 1.x. Mountpoints lists the mount points where the logical volumes should be mounted. Number of mount points should be equal to the number of logical volumes. For example:
      [backend-setup]
      devices=sda,sdb,sdc
      vgs=custom_vg1,custom_vg2,custom_vg3
      pools=custom_pool1,custom_pool2,custom_pool3
      lvs=custom_lv1,custom_lv2,custom_lv3
      mountpoints=/gluster/data1,/gluster/data2,/gluster/data3
    • ssd - This variable is set if caching has to be added. For example, the backed setup with ssd for caching should be:
      [backend-setup]
      ssd=sdc
      vgs=RHS_vg1
      datalv=lv_data
      cachedatalv=lv_cachedata:1G
      cachemetalv=lv_cachemeta:230G

      Note

      Specifying the name of the data LV is necessary while adding SSD. Make sure the datalv is created already. Otherwise ensure to create it in one of the earlier `backend-setup’ sections.
  • PV

    Available in gdeploy 2.0. If the user needs to have more control over setting up the backend, and does not want to use backend-setup section, then pv, vg, and lv modules are to be used. The pv module supports the following variables.

    • action: Mandatory. Supports two values, 'create' and 'resize'
      Example: Creating physical volumes
      [pv]
      action=create
      devices=vdb,vdc,vdd
      Example: Creating physical volumes on a specific host
      [pv:10.0.5.2]
      action=create
      devices=vdb,vdc,vdd
    • devices: Mandatory. The list of devices to use for pv creation.
    • expand: Used when action=resize.
      Example: Expanding an already created pv
      [pv]
      action=resize
      devices=vdb
      expand=yes
    • shrink: Used when action=resize.
      Example: Shrinking an already created pv
      [pv]
      action=resize
      devices=vdb
      shrink=100G
    • dalign:
      The Logical Volume Manager can use a portion of the physical volume for storing its metadata while the rest is used as the data portion. Align the I/O at the Logical Volume Manager (LVM) layer using the dalign option while creating the physical volume. For example:
      [pv]
      action=create
      devices=sdb,sdc,sdd,sde
      dalign=256k
      For JBOD, use an alignment value of 256K. For hardware RAID, the alignment value should be obtained by multiplying the RAID stripe unit size with the number of data disks. If 12 disks are used in a RAID 6 configuration, the number of data disks is 10; on the other hand, if 12 disks are used in a RAID 10 configuration, the number of data disks is 6.
      The following example is appropriate for 12 disks in a RAID 6 configuration with a stripe unit size of 128 KiB:
      [pv]
      action=create
      devices=sdb,sdc,sdd,sde
      dalign=1280k
      The following example is appropriate for 12 disks in a RAID 10 configuration with a stripe unit size of 256 KiB:
      [pv]
      action=create
      devices=sdb,sdc,sdd,sde
      dalign=1536k
      To view the previously configured physical volume settings for the dalign option, run the pvs -o +pe_start device command. For example:
      # pvs -o +pe_start /dev/sdb
      PV         VG   Fmt  Attr PSize PFree 1st PE
      /dev/sdb        lvm2 a--  9.09t 9.09t   1.25m
      You can also set the dalign option in the backend-setup section.
  • VG

    Available in gdeploy 2.0. This module is used to create and extend volume groups. The vg module supports the following variables.

    • action - Action can be one of create or extend.
    • pvname - PVs to use to create the volume. For more than one PV use comma separated values.
    • vgname - The name of the vg. If no name is provided GLUSTER_vg will be used as default name.
    • one-to-one - If set to yes, one-to-one mapping will be done between pv and vg.
    If action is set to extend, the vg will be extended to include pv provided.
    Example1: Create a vg named images_vg with two PVs
    [vg]
    action=create
    vgname=images_vg
    pvname=sdb,sdc
    Example2: Create two vgs named rhgs_vg1 and rhgs_vg2 with two PVs
    [vg]
    action=create
    vgname=rhgs_vg
    pvname=sdb,sdc
    one-to-one=yes
    Example3: Extend an existing vg with the given disk.
    [vg]
    action=extend
    vgname=rhgs_images
    pvname=sdc
  • LV

    Available in gdeploy 2.0. This module is used to create, setup-cache, and convert logical volumes. The lv module supports the following variables:

    action - The action variable allows three values `create’, `setup-cache’, `convert’, and `change’. If the action is 'create', the following options are supported:
    • lvname: The name of the logical volume, this is an optional field. Default is GLUSTER_lv
    • poolname - Name of the thinpool volume name, this is an optional field. Default is GLUSTER_pool
    • lvtype - Type of the logical volume to be created, allowed values are `thin’ and `thick’. This is an optional field, default is thick.
    • size - Size of the logical volume volume. Default is to take all available space on the vg.
    • extent - Extent size, default is 100%FREE
    • force - Force lv create, do not ask any questions. Allowed values `yes’, `no’. This is an optional field, default is yes.
    • vgname - Name of the volume group to use.
    • pvname - Name of the physical volume to use.
    • chunksize - The size of the chunk unit used for snapshots, cache pools, and thin pools. By default this is specified in kilobytes. For RAID 5 and 6 volumes, gdeploy calculates the default chunksize by multiplying the stripe size and the disk count. For RAID 10, the default chunksize is 256 KB. See Section 19.2, “Brick Configuration” for details.

      Warning

      Red Hat recommends using at least the default chunksize. If the chunksize is too small and your volume runs out of space for metadata, the volume is unable to create data. This includes the data required to increase the size of the metadata pool or to migrate data away from a volume that has run out of metadata space. Red Hat recommends monitoring your logical volumes to ensure that they are expanded or more storage created before metadata volumes become completely full.
    • poolmetadatasize - Sets the size of pool's metadata logical volume. Allocate the maximum chunk size (16 GiB) if possible. If you allocate less than the maximum, allocate at least 0.5% of the pool size to ensure that you do not run out of metadata space.

      Warning

      If your metadata pool runs out of space, you cannot create data. This includes the data required to increase the size of the metadata pool or to migrate data away from a volume that has run out of metadata space. Monitor your metadata pool using the lvs -o+metadata_percent command and ensure that it does not run out of space.
    • virtualsize - Creates a thinly provisioned device or a sparse device of the given size
    • mkfs - Creates a filesystem of the given type. Default is to use xfs.
    • mkfs-opts - mkfs options.
    • mount - Mount the logical volume.
    If the action is setup-cache, the below options are supported:
    • ssd - Name of the ssd device. For example sda/vda/ … to setup cache.
    • vgname - Name of the volume group.
    • poolname - Name of the pool.
    • cache_meta_lv - Due to requirements from dm-cache (the kernel driver), LVM further splits the cache pool LV into two devices - the cache data LV and cache metadata LV. Provide the cache_meta_lv name here.
    • cache_meta_lvsize - Size of the cache meta lv.
    • cache_lv - Name of the cache data lv.
    • cache_lvsize - Size of the cache data.
    • force - Force
    If the action is convert, the below options are supported:
    • lvtype - type of the lv, available options are thin and thick
    • force - Force the lvconvert, default is yes.
    • vgname - Name of the volume group.
    • poolmetadata - Specifies cache or thin pool metadata logical volume.
    • cachemode - Allowed values writeback, writethrough. Default is writethrough.
    • cachepool - This argument is necessary when converting a logical volume to a cache LV. Name of the cachepool.
    • lvname - Name of the logical volume.
    • chunksize - The size of the chunk unit used for snapshots, cache pools, and thin pools. By default this is specified in kilobytes. For RAID 5 and 6 volumes, gdeploy calculates the default chunksize by multiplying the stripe size and the disk count. For RAID 10, the default chunksize is 256 KB. See Section 19.2, “Brick Configuration” for details.

      Warning

      Red Hat recommends using at least the default chunksize. If the chunksize is too small and your volume runs out of space for metadata, the volume is unable to create data. Red Hat recommends monitoring your logical volumes to ensure that they are expanded or more storage created before metadata volumes become completely full.
    • poolmetadataspare - Controls creation and maintanence of pool metadata spare logical volume that will be used for automated pool recovery.
    • thinpool - Specifies or converts logical volume into a thin pool's data volume. Volume’s name or path has to be given.
    If the action is change, the below options are supported:
    • lvname - Name of the logical volume.
    • vgname - Name of the volume group.
    • zero - Set zeroing mode for thin pool.
    Example 1: Create a thin LV
    [lv]
    action=create
    vgname=RHGS_vg1
    poolname=lvthinpool
    lvtype=thinpool
    poolmetadatasize=200MB
    chunksize=1024k
    size=30GB
    Example 2: Create a thick LV
    [lv]
    action=create
    vgname=RHGS_vg1
    lvname=engine_lv
    lvtype=thick
    size=10GB
    mount=/rhgs/brick1
    If there are more than one LVs, then the LVs can be created by numbering the LV sections, like [lv1], [lv2] …
  • RH-subscription

    Available in gdeploy 2.0. This module is used to subscribe, unsubscribe, attach, enable repos etc. The RH-subscription module allows the following variables:

    This module is used to subscribe, unsubscribe, attach, enable repos etc. The RH-subscription module allows the following variables:
    If the action is register, the following options are supported:
    • username/activationkey: Username or activationkey.
    • password/activationkey: Password or activation key
    • auto-attach: true/false
    • pool: Name of the pool.
    • repos: Repos to subscribe to.
    • disable-repos: Repo names to disable. Leaving this option blank will disable all the repos.
    • ignore_register_errors: If set to no, gdeploy will exit if system registration fails.
    • If the action is attach-pool the following options are supported:
      pool - Pool name to be attached.
      ignore_attach_pool_errors - If set to no, gdeploy fails if attach-pool fails.
    • If the action is enable-repos the following options are supported:
      repos - List of comma separated repos that are to be subscribed to.
      ignore_enable_errors - If set to no, gdeploy fails if enable-repos fail.
    • If the action is disable-repos the following options are supported:
      repos - List of comma separated repos that are to be subscribed to.
      ignore_disable_errors - If set to no, gdeploy fails if disable-repos fail
    • If the action is unregister the systems will be unregistered.
      ignore_unregister_errors - If set to no, gdeploy fails if unregistering fails.
    Example 1: Subscribe to Red Hat Subscription network:
    [RH-subscription1]
    action=register
    username=qa@redhat.com
    password=<passwd>
    pool=<pool>
    ignore_register_errors=no
    Example 2: Disable all the repos:
    [RH-subscription2]
    action=disable-repos
    repos=*
    Example 3: Enable a few repos
    [RH-subscription3]
    action=enable-repos
    repos=rhel-7-server-rpms,rh-gluster-3-for-rhel-7-server-rpms,rhel-7-server-rhev-mgmt-agent-rpms
    ignore_enable_errors=no
  • yum

    Available in gdeploy 2.0. This module is used to install or remove rpm packages, with the yum module we can add repos as well during the install time.

    The action variable allows two values `install’ and `remove’.
    If the action is install the following options are supported:
    • packages - Comma separated list of packages that are to be installed.
    • repos - The repositories to be added.
    • gpgcheck - yes/no values have to be provided.
    • update - Whether yum update has to be initiated.
    If the action is remove then only one option has to be provided:
    • remove - The comma separated list of packages to be removed.
    For example
    [yum1]
    action=install
    gpgcheck=no
    # Repos should be an url; eg: http://repo-pointing-glusterfs-builds
    repos=<glusterfs.repo>,<vdsm.repo>
    packages=vdsm,vdsm-gluster,ovirt-hosted-engine-setup,screen,xauth
    update=yes
    Install a package on a particular host.
    [yum2:host1]
    action=install
    gpgcheck=no
    packages=rhevm-appliance
  • shell

    Available in gdeploy 2.0. This module allows user to run shell commands on the remote nodes.

    Currently shell provides a single action variable with value execute. And a command variable with any valid shell command as value.
    The below command will execute vdsm-tool on all the nodes.
    [shell]
    action=execute
    command=vdsm-tool configure --force
  • update-file

    Available in gdeploy 2.0. update-file module allows users to copy a file, edit a line in a file, or add new lines to a file. action variable can be any of copy, edit, or add.

    When the action variable is set to copy, the following variables are supported.
    • src - The source path of the file to be copied from.
    • dest - The destination path on the remote machine to where the file is to be copied to.
    When the action variable is set to edit, the following variables are supported.
    • dest - The destination file name which has to be edited.
    • replace - A regular expression, which will match a line that will be replaced.
    • line - Text that has to be replaced.
    When the action variable is set to add, the following variables are supported.
    • dest - File on the remote machine to which a line has to be added.
    • line - Line which has to be added to the file. Line will be added towards the end of the file.
    Example 1: Copy a file to a remote machine.
    [update-file]
    action=copy
    src=/tmp/foo.cfg
    Example 2: Edit a line in the remote machine, in the below example lines that have allowed_hosts will be replaced with allowed_hosts=host.redhat.com
    [update-file]
    action=edit
    replace=allowed_hosts
    line=allowed_hosts=host.redhat.com
    Example 3: Add a line to the end of a file
    For Red Hat Enterprise Linux 7:
    [update-file]
    action=add
    dest=/etc/ntp.conf
    line=server clock.redhat.com iburst
    For Red Hat Enterprise Linux 8:
    [update-file]
    action=add
    dest=/etc/chrony.conf
    line=server 0.rhel.pool.ntp.org iburst
  • service

    Available in gdeploy 2.0. The service module allows user to start, stop, restart, reload, enable, or disable a service. The action variable specifies these values.

    When action variable is set to any of start, stop, restart, reload, enable, disable the variable servicename specifies which service to start, stop etc.
    • service - Name of the service to start, stop etc.
    For Red Hat Enterprise Linux 7:
    Example: enable and start ntp daemon.
    [service1]
    action=enable
    service=ntpd
    [service2]
    action=restart
    service=ntpd
    For Red Hat Enterprise Linux 8:
    Example: enable and start chrony daemon.
    [service1]
    action=enable
    service=chrony
    [service2]
    action=restart
    service=chrony
  • script

    Available in gdeploy 2.0. script module enables user to execute a script/binary on the remote machine. action variable is set to execute. Allows user to specify two variables file and args.

    • file - An executable on the local machine.
    • args - Arguments to the above program.
    Example: Execute script disable-multipath.sh on all the remote nodes listed in `hosts’ section.
    [script]
    action=execute
    file=/usr/share/ansible/gdeploy/scripts/disable-multipath.sh
  • firewalld

    Available in gdeploy 2.0. firewalld module allows the user to manipulate firewall rules. action variable supports two values `add’ and `delete’. Both add and delete support the following variables:

    • ports/services - The ports or services to add to firewall.
    • permanent - Whether to make the entry permanent. Allowed values are true/false
    • zone - Default zone is public
    For example:
    [firewalld]
    action=add
    ports=111/tcp,2049/tcp,54321/tcp,5900/tcp,5900-6923/tcp,5666/tcp,16514/tcp
    services=glusterfs
  • geo-replication

    Available in gdeploy 2.0.2, geo-replication module allows the user to configure geo-replication, control and verify geo-replication sessions. The following are the supported variables:

    • action - The action to be performed for the geo-replication session.
      • create - To create a geo-replication session.
      • start - To start a created geo-replication session.
      • stop - To stop a started geo-replication session.
      • pause - To pause a geo-replication session.
      • resume - To resume a paused geo-replication session.
      • delete - To delete a geo-replication session.
    • georepuser - Username to be used for the action being performed

      Important

      If georepuser variable is omitted, the user is assumed to be root user.
    • mastervol - Master volume details in the following format:
      Master_HostName:Master_VolName
    • slavevol - Slave volume details in the following format:
      Slave_HostName:Slave_VolName
    • slavenodes - Slave node IP addresses in the following format:
      Slave1_IPAddress,Slave2_IPAddress

      Important

      Slave IP addresses must be comma (,) separated.
    • force - Force the system to perform the action. Allowed values are yes or no.
    • start - Start the action specified in the configuration file. Allowed values are yes or no. Default value is yes.
    For example:
    [geo-replication]
    action=create
    georepuser=testgeorep
    mastervol=10.1.1.29:mastervolume
    slavevol=10.1.1.25:slavevolume
    slavenodes=10.1.1.28,10.1.1.86
    force=yes
    start=yes

5.1.8. Deploying NFS Ganesha using gdeploy

gdeploy supports the deployment and configuration of NFS Ganesha on Red Hat Gluster Storage 3.5, from gdeploy version 2.0.2-35.
NFS-Ganesha is a user space file server for the NFS protocol. For more information about NFS-Ganesha see https://access.redhat.com/documentation/en-us/red_hat_gluster_storage/3.5/html-single/administration_guide/#nfs_ganesha

5.1.8.1. Prerequisites

Ensure that the following prerequisites are met:
Subscribing to Subscription Manager

You must subscribe to subscription manager and obtain the NFS Ganesha packages before continuing further.

Add the following details to the configuration file to subscribe to subscription manager:
[RH-subscription1]
action=register
username=<user>@redhat.com
password=<password>
pool=<pool-id>
Execute the following command to run the configuration file:
# gdeploy -c txt.conf
Enabling Repos

To enable the required repos, add the following details in the configuration file:

[RH-subscription2]
action=enable-repos
repos=rhel-7-server-rpms,rh-gluster-3-for-rhel-7-server-rpms,rh-gluster-3-nfs-for-rhel-7-server-rpms,rhel-ha-for-rhel-7-server-rpms,rhel-7-server-ansible-2-rpms
Execute the following command to run the configuration file:
# gdeploy -c txt.conf
Enabling Firewall Ports

To enable the firewall ports, add the following details in the configuration file:

[firewalld]
action=add
ports=111/tcp,2049/tcp,54321/tcp,5900/tcp,5900-6923/tcp,5666/tcp,16514/tcp
services=glusterfs,nlm,nfs,rpc-bind,high-availability,mountd,rquota

Note

To ensure NFS client UDP mount does not fail, ensure to add port 2049/udp in [firewalld] section of gdeploy.
Execute the following command to run the configuration file:
# gdeploy -c txt.conf
Installing the Required Package:

To install the required package, add the following details in the configuration file

[yum]
action=install
repolist=
gpgcheck=no
update=no
packages=glusterfs-ganesha
Execute the following command to run the configuration file:
# gdeploy -c txt.conf

5.1.8.2. Supported Actions

The NFS Ganesha module in gdeploy allows the user to perform the following actions:
  • Creating a Cluster
  • Destroying a Cluster
  • Adding a Node
  • Deleting a Node
  • Exporting a Volume
  • Unexporting a Volume
  • Refreshing NFS Ganesha Configuration
Creating a Cluster

This action creates a fresh NFS-Ganesha setup on a given volume. For this action the nfs-ganesha in the configuration file section supports the following variables:

  • ha-name: This is an optional variable. By default it is ganesha-ha-360.
  • cluster-nodes: This is a required argument. This variable expects comma separated values of cluster node names, which is used to form the cluster.
  • vip: This is a required argument. This variable expects comma separated list of ip addresses. These will be the virtual ip addresses.
  • volname: This is an optional variable if the configuration contains the [volume] section
For example: To create a NFS-Ganesha cluster add the following details in the configuration file:
[hosts]
host-1.example.com
host-2.example.com
host-3.example.com
host-4.example.com

[backend-setup]
devices=/dev/vdb
vgs=vg1
pools=pool1
lvs=lv1
mountpoints=/mnt/brick

[firewalld]
action=add
ports=111/tcp,2049/tcp,54321/tcp,5900/tcp,5900-6923/tcp,5666/tcp,16514/tcp,662/tcp,662/udp
services=glusterfs,nlm,nfs,rpc-bind,high-availability,mountd,rquota

[volume]
action=create
volname=ganesha
transport=tcp
replica_count=3
force=yes

#Creating a high availability cluster and exporting the volume
[nfs-ganesha]
action=create-cluster
ha-name=ganesha-ha-360
cluster-nodes=host-1.example.com,host-2.example.com,host-3.example.com,host-4   .example.com
vip=10.70.44.121,10.70.44.122
volname=ganesha
ignore_ganesha_errors=no
In the above example, it is assumed that the required packages are installed, a volume is created and NFS-Ganesha is enabled on it.
Execute the configuration using the following command:
# gdeploy -c txt.conf
Destroying a Cluster

The action, destroy-cluster cluster disables NFS Ganesha. It allows one variable, cluster-nodes.

For example: To destroy a NFS-Ganesha cluster add the following details in the configuration file:
[hosts]
host-1.example.com
host-2.example.com

# To destroy the high availability cluster

[nfs-ganesha]
action=destroy-cluster
cluster-nodes=host-1.example.com,host-2.example.com
Execute the configuration using the following command:
# gdeploy -c txt.conf
Adding a Node

The add-node action allows three variables:

  • nodes: Accepts a list of comma separated hostnames that have to be added to the cluster
  • vip: Accepts a list of comma separated ip addresses.
  • cluster_nodes: Accepts a list of comma separated nodes of the NFS Ganesha cluster.
For example, to add a node, add the following details to the configuration file:
[hosts]
host-1.example.com
host-2.example.com
host-3.example.com

[peer]
action=probe

[clients]
action=mount
volname=host-3.example.com:gluster_shared_storage
hosts=host-3.example.com
fstype=glusterfs
client_mount_points=/var/run/gluster/shared_storage/


[nfs-ganesha]
action=add-node
nodes=host-3.example.com
cluster_nodes=host-1.example.com,host-2.example.com
vip=10.0.0.33

Note

With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
Execute the configuration using the following command:
# gdeploy -c txt.conf
Deleting a Node

The delete-node action takes one variable, nodes, which specifies the node or nodes to delete from the NFS Ganesha cluster in a comma delimited list.

For example:
[hosts]
host-1.example.com
host-2.example.com
host-3.example.com
host-4.example.com

[nfs-ganesha]
action=delete-node
nodes=host-2.example.com
Exporting a Volume

This action exports a volume. export-volume action supports one variable, volname.

For example, to export a volume, add the following details to the configuration file:
[hosts]
host-1.example.com
host-2.example.com

[nfs-ganesha]
action=export-volume
volname=ganesha
Execute the configuration using the following command:
# gdeploy -c txt.conf
Unexporting a Volume:

This action unexports a volume. unexport-volume action supports one variable, volname.

For example, to unexport a volume, add the following details to the configuration file:
[hosts]
host-1.example.com
host-2.example.com

[nfs-ganesha]
action=unexport-volume
volname=ganesha
Execute the configuration using the following command:
# gdeploy -c txt.conf
Refreshing NFS Ganesha Configuration

This action will add/delete or add a config block to the configuration file and runs refresh-config on the cluster.

The action refresh-config supports the following variables:
  • del-config-lines
  • block-name
  • volname
  • ha-conf-dir
  • update_config_lines
Example 1 - To add a client block and run refresh-config add the following details to the configuration file:

Note

refresh-config with client block has few limitations:
  • Works for only one client
  • User cannot delete a line from a config block
[hosts]
host1-example.com
host2-example.com

[nfs-ganesha]
action=refresh-config
# Default block name is `client'
block-name=client
config-block=clients = 10.0.0.1;|allow_root_access = true;|access_type = "RO";|Protocols = "2", "3";|anonymous_uid = 1440;|anonymous_gid = 72;
volname=ganesha
Execute the configuration using the following command:
# gdeploy -c txt.conf
Example 2 - To delete a line and run refresh-config add the following details to the configuration file:
[hosts]
host1-example.com
host2-example.com


[nfs-ganesha]
action=refresh-config
del-config-lines=client
volname=ganesha
Execute the configuration using the following command:
# gdeploy -c txt.conf
Example 3 - To run refresh-config on a volume add the following details to the configuration file:
[hosts]
host1-example.com
host2-example.com


[nfs-ganesha]
action=refresh-config
volname=ganesha
Execute the configuration using the following command:
# gdeploy -c txt.conf
Example 4 - To modify a line and run refresh-config add the following details to the configuration file:
[hosts]
host1-example.com
host2-example.com


[nfs-ganesha]
action=refresh-config
update_config_lines=Access_type = "RO";
#update_config_lines=Protocols = "4";
#update_config_lines=clients = 10.0.0.1;
volname=ganesha
Execute the configuration using the following command:
# gdeploy -c txt.conf

5.1.9. Deploying Samba / CTDB using gdeploy

The Server Message Block (SMB) protocol can be used to access Red Hat Gluster Storage volumes by exporting directories in GlusterFS volumes as SMB shares on the server. In Red Hat Gluster Storage, Samba is used to share volumes through SMB protocol.

5.1.9.1. Prerequisites

Ensure that the following prerequisites are met:
Subscribing to Subscription Manager

You must subscribe to subscription manager and obtain the Samba packages before continuing further.

Add the following details to the configuration file to subscribe to subscription manager:
[RH-subscription1]
action=register
username=<user>@redhat.com
password=<password>
pool=<pool-id>
Execute the following command to run the configuration file:
# gdeploy -c txt.conf
Enabling Repos

To enable the required repos, add the following details in the configuration file:

Red Hat Enterprise Linux 7
[RH-subscription2]
action=enable-repos
repos=rhel-7-server-rpms,rh-gluster-3-for-rhel-7-server-rpms,rh-gluster-3-samba-for-rhel-7-server-rpms,rhel-7-server-ansible-2-rpms
Red Hat Enterprise Linux 8
[RH-subscription2]
action=enable-repos
rh-gluster-3-for-rhel-8-x86_64-rpms,ansible-2-for-rhel-8-x86_64-rpms,rhel-8-for-x86_64-baseos-rpms,rhel-8-for-x86_64-appstream-rpms,rhel-8-for-x86_64-highavailability-rpms,rh-gluster-3-samba-for-rhel-8-x86_64-rpms
Execute the following command to run the configuration file:
# gdeploy -c txt.conf
Enabling Firewall Ports

To enable the firewall ports, add the following details in the configuration file:

[firewalld]
action=add
ports=54321/tcp,5900/tcp,5900-6923/tcp,5666/tcp,4379/tcp
services=glusterfs,samba,high-availability
Execute the following command to run the configuration file:
# gdeploy -c txt.conf
Installing the Required Package:

To install the required package, add the following details in the configuration file

[yum]
action=install
repolist=
gpgcheck=no
update=no
packages=samba,samba-client,glusterfs-server,ctdb
Execute the following command to run the configuration file:
# gdeploy -c txt.conf

5.1.9.2. Setting up Samba

Samba can be enabled in two ways:
  • Enabling Samba on an existing volume
  • Enabling Samba while creating a volume
Enabling Samba on an existing volume

If a Red Hat Gluster Storage volume is already present, then the user has to mention the action as smb-setup in the volume section. It is necessary to mention all the hosts that are in the cluster, as gdeploy updates the glusterd configuration files on each of the hosts.

For example, to enable Samba on an existing volume, add the following details to the configuration file:
[hosts]
10.70.37.192
10.70.37.88

[volume]
action=smb-setup
volname=samba1
force=yes
smb_username=smbuser
smb_mountpoint=/mnt/smb

Note

Ensure that the hosts are not part of the CTDB cluster.
Execute the configuration using the following command:
# gdeploy -c txt.conf
Enabling Samba while creating a Volume

If Samba has be set up while creating a volume, the a variable smb has to be set to yes in the configuration file.

For example, to enable Samba while creating a volume, add the following details to the configuration file:
[hosts]
10.70.37.192
10.70.37.88
10.70.37.65

[backend-setup]
devices=/dev/vdb
vgs=vg1
pools=pool1
lvs=lv1
mountpoints=/mnt/brick

[volume]
action=create
volname=samba1
smb=yes
force=yes
smb_username=smbuser
smb_mountpoint=/mnt/smb
Execute the configuration using the following command:
# gdeploy -c txt.conf

Note

In both the cases of enabling Samba, smb_username and smb_mountpoint are necessary if samba has to be setup with the acls set correctly.

5.1.9.3. Setting up CTDB

Using CTDB requires setting up a separate volume in order to protect the CTDB lock file. Red Hat recommends a replicated volume where the replica count is equal to the number of servers being used as Samba servers.
The following configuration file sets up a CTDB volume across two hosts that are also Samba servers.
[hosts]
10.70.37.192
10.70.37.88
10.70.37.65

[volume]
action=create
volname=ctdb
transport=tcp
replica_count=3
force=yes

[ctdb]
action=setup
public_address=10.70.37.6/24 eth0,10.70.37.8/24 eth0
volname=ctdb
You can configure the CTDB cluster to use separate IP addresses by using the ctdb_nodes parameter, as shown in the following example.
[hosts]
10.70.37.192
10.70.37.88
10.70.37.65

[volume]
action=create
volname=ctdb
transport=tcp
replica_count=3
force=yes

[ctdb]
action=setup
public_address=10.70.37.6/24 eth0,10.70.37.8/24 eth0
ctdb_nodes=192.168.1.1,192.168.2.5
volname=ctdb
Execute the configuration using the following command:
# gdeploy -c txt.conf

5.1.10. Enabling SSL on a Volume

You can create volumes with SSL enabled, or enable SSL on an exisiting volumes using gdeploy (v2.0.1 onwards). This section explains how the configuration files should be written for gdeploy to enable SSL.

5.1.10.1. Creating a Volume and Enabling SSL

To create a volume and enable SSL on it, add the following details to the configuration file:
[hosts]
10.70.37.147
10.70.37.47
10.70.37.13

[backend-setup]
devices=/dev/vdb
vgs=vg1
pools=pool1
lvs=lv1
mountpoints=/mnt/brick

[volume]
action=create
volname=vol1
transport=tcp
replica_count=3
force=yes
enable_ssl=yes
ssl_clients=10.70.37.107,10.70.37.173
brick_dirs=/data/1

[clients]
action=mount
hosts=10.70.37.173,10.70.37.107
volname=vol1
fstype=glusterfs
client_mount_points=/mnt/data
In the above example, a volume named vol1 is created and SSL is enabled on it. gdeploy creates self signed certificates.
After adding the details to the configuration file, execute the following command to run the configuration file:
# gdeploy -c txt.conf

5.1.10.2. Enabling SSL on an Existing Volume:

To enable SSL on an existing volume, add the following details to the configuration file:
[hosts]
10.70.37.147
10.70.37.47

# It is important for the clients to be unmounted before setting up SSL
[clients1]
action=unmount
hosts=10.70.37.173,10.70.37.107
client_mount_points=/mnt/data

[volume]
action=enable-ssl
volname=vol2
ssl_clients=10.70.37.107,10.70.37.173

[clients2]
action=mount
hosts=10.70.37.173,10.70.37.107
volname=vol2
fstype=glusterfs
client_mount_points=/mnt/data
After adding the details to the configuration file, execute the following command to run the configuration file:
# gdeploy -c txt.conf

5.1.11. Gdeploy log files

Because gdeploy is usually run by non-privileged users, by default, gdeploy log files are written to /home/username/.gdeploy/logs/gdeploy.log instead of the /var/log directory.
You can change the log location by setting a different location as the value of the GDEPLOY_LOGFILE environment variable. For example, to set the gdeploy log location to /var/log/gdeploy/gdeploy.log for this session, run the following command:
$ export GDEPLOY_LOGFILE=/var/log/gdeploy/gdeploy.log
To persistently set this as the default log location for this user, add the same command as a separate line in the /home/username/.bash_profile file for that user.

5.2. About Encrypted Disk

Red Hat Gluster Storage provides the ability to create bricks on encrypted devices to restrict data access. Encrypted bricks can be used to create Red Hat Gluster Storage volumes.
For information on creating encrypted disk, refer to the following product documentation:
  • For RHEL 6, refer to Disk Encryption Appendix of the Red Hat Enterprise Linux 6 Installation Guide.

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  • For RHEL 7, refer to Encryption of the Red Hat Enterprise Linux 7 Security Guide.
  • Starting in RHEL 7.5, Red Hat has implemented an additional component that can be used to enable LUKS disks remotely during startup called as Network Bound Disk Encryption (NBDE). For more information on NBDE, refer to Configuring Automated Unlocking of Encrypted Volumes using Policy-Based Decryption of the Red Hat Enterprise Linux 7 Security Guide.
  • For RHEL 8, refer to Encrypting Block Devices Using LUKS of the Red Hat Enterprise Linux 8 Security Guide.

5.3. Formatting and Mounting Bricks

To create a Red Hat Gluster Storage volume, specify the bricks that comprise the volume. After creating the volume, the volume must be started before it can be mounted.

5.3.1. Creating Bricks Manually

Important

  • Red Hat supports formatting a Logical Volume using the XFS file system on the bricks.
  • Red Hat supports heterogeneous subvolume sizes for distributed volumes (either pure distributed, distributed-replicated or distributed-dispersed). Red Hat does not support heterogeneous brick sizes for bricks of the same subvolume.
    For example, you can have a distributed-replicated 3x3 volume with 3 bricks of 10GiB, 3 bricks of 50GiB and 3 bricks of 100GiB as long as the 3 10GiB bricks belong to the same replicate and similarly the 3 50GiB and 100GiB bricks belong to the same replicate set. In this way you will have 1 subvolume of 10GiB, another of 50GiB and 100GiB. The distributed hash table balances the number of assigned files to each subvolume so that the subvolumes get filled proportionally to their size.

5.3.1.1. Creating a Thinly Provisioned Logical Volume

  1. Create a physical volume(PV) by using the pvcreate command.
    # pvcreate --dataalignment alignment_value device
    For example:
    # pvcreate --dataalignment 1280K /dev/sdb
    Here, /dev/sdb is a storage device.
    Use the correct dataalignment option based on your device. For more information, see Section 19.2, “Brick Configuration”

    Note

    The device name and the alignment value will vary based on the device you are using.
  2. Create a Volume Group (VG) from the PV using the vgcreate command:
    # vgcreate --physicalextentsize alignment_value volgroup device
    For example:
    # vgcreate --physicalextentsize 1280K rhs_vg /dev/sdb
  3. Create a thin-pool using the following commands:
    # lvcreate --thin volgroup/poolname --size pool_sz --chunksize chunk_sz --poolmetadatasize metadev_sz --zero n
    
    For example:
    # lvcreate --thin rhs_vg/rhs_pool --size 2T --chunksize 1280K --poolmetadatasize 16G --zero n
    Ensure you read Chapter 19, Tuning for Performance to select appropriate values for chunksize and poolmetadatasize.
  4. Create a thinly provisioned volume that uses the previously created pool by running the lvcreate command with the --virtualsize and --thin options:
    # lvcreate --virtualsize size --thin volgroup/poolname --name volname
    For example:
    # lvcreate --virtualsize 1G --thin rhs_vg/rhs_pool --name rhs_lv
    It is recommended that only one LV should be created in a thin pool.
  5. Format bricks using the supported XFS configuration, mount the bricks, and verify the bricks are mounted correctly. To enhance the performance of Red Hat Gluster Storage, ensure you read Chapter 19, Tuning for Performance before formatting the bricks.

    Important

    Snapshots are not supported on bricks formatted with external log devices. Do not use -l logdev=device option with mkfs.xfs command for formatting the Red Hat Gluster Storage bricks.
    # mkfs.xfs -f -i size=512 -n size=8192 -d su=128k,sw=10 device
    DEVICE is the created thin LV. The inode size is set to 512 bytes to accommodate for the extended attributes used by Red Hat Gluster Storage.
  6. Run # mkdir /mountpoint to create a directory to link the brick to.
    # mkdir /rhgs
  7. Add an entry in /etc/fstab:
    /dev/volgroup/volname /mountpoint  xfs rw,inode64,noatime,nouuid,x-systemd.device-timeout=10min  1 2
    For example:
    /dev/rhs_vg/rhs_lv /rhgs  xfs rw,inode64,noatime,nouuid,x-systemd.device-timeout=10min  1 2
  8. Run mount /mountpoint to mount the brick.
  9. Run the df -h command to verify the brick is successfully mounted:
    # df -h
    /dev/rhs_vg/rhs_lv   16G  1.2G   15G   7% /rhgs
  10. If SElinux is enabled, then the SELinux labels that has to be set manually for the bricks created using the following commands:
    # semanage fcontext -a -t glusterd_brick_t /rhgs/brick1
    # restorecon -Rv /rhgs/brick1

5.3.2. Using Subdirectory as the Brick for Volume

You can create an XFS file system, mount them and point them as bricks while creating a Red Hat Gluster Storage volume. If the mount point is unavailable, the data is directly written to the root file system in the unmounted directory.
For example, the /rhgs directory is the mounted file system and is used as the brick for volume creation. However, for some reason, if the mount point is unavailable, any write continues to happen in the /rhgs directory, but now this is under root file system.
To overcome this issue, you can perform the below procedure.
During Red Hat Gluster Storage setup, create an XFS file system and mount it. After mounting, create a subdirectory and use this subdirectory as the brick for volume creation. Here, the XFS file system is mounted as /bricks. After the file system is available, create a directory called /rhgs/brick1 and use it for volume creation. Ensure that no more than one brick is created from a single mount. This approach has the following advantages:
  • When the /rhgs file system is unavailable, there is no longer/rhgs/brick1 directory available in the system. Hence, there will be no data loss by writing to a different location.
  • This does not require any additional file system for nesting.
Perform the following to use subdirectories as bricks for creating a volume:
  1. Create the brick1 subdirectory in the mounted file system.
    # mkdir /rhgs/brick1
    Repeat the above steps on all nodes.
  2. Create the Red Hat Gluster Storage volume using the subdirectories as bricks.
    # gluster volume create distdata01 ad-rhs-srv1:/rhgs/brick1
    ad-rhs-srv2:/rhgs/brick2
  3. Start the Red Hat Gluster Storage volume.
    # gluster volume start distdata01
  4. Verify the status of the volume.
    # gluster  volume status distdata01

Note

If multiple bricks are used from the same server, then ensure the bricks are mounted in the following format. For example:
# df -h

/dev/rhs_vg/rhs_lv1   16G  1.2G   15G   7% /rhgs1
/dev/rhs_vg/rhs_lv2   16G  1.2G   15G   7% /rhgs2
Create a distribute volume with 2 bricks from each server. For example:
# gluster volume create test-volume server1:/rhgs1/brick1 server2:/rhgs1/brick1 server1:/rhgs2/brick2 server2:/rhgs2/brick2

5.3.3.  Reusing a Brick from a Deleted Volume

Bricks can be reused from deleted volumes, however some steps are required to make the brick reusable.
Brick with a File System Suitable for Reformatting (Optimal Method)
Run # mkfs.xfs -f -i size=512 device to reformat the brick to supported requirements, and make it available for immediate reuse in a new volume.

Note

All data will be erased when the brick is reformatted.
File System on a Parent of a Brick Directory
If the file system cannot be reformatted, remove the whole brick directory and create it again.

5.3.4. Cleaning An Unusable Brick

If the file system associated with the brick cannot be reformatted, and the brick directory cannot be removed, perform the following steps:
  1. Delete all previously existing data in the brick, including the .glusterfs subdirectory.
  2. Run # setfattr -x trusted.glusterfs.volume-id brick and # setfattr -x trusted.gfid brick to remove the attributes from the root of the brick.
  3. Run # getfattr -d -m . brick to examine the attributes set on the volume. Take note of the attributes.
  4. Run # setfattr -x attribute brick to remove the attributes relating to the glusterFS file system.
    The trusted.glusterfs.dht attribute for a distributed volume is one such example of attributes that need to be removed.

5.4. Creating Distributed Volumes

This type of volume spreads files across the bricks in the volume.
Illustration of a distributed volume consisting of two servers. Two files are shown on the server1 brick, and one file is shown on the server2 brick. The distributed volume is set to a single mount point.

Figure 5.1. Illustration of a Distributed Volume

Warning

Distributed volumes can suffer significant data loss during a disk or server failure because directory contents are spread randomly across the bricks in the volume and hence require an architecture review before using them in production.
Please reach out to your Red Hat account team to arrange an architecture review should you intend to use distributed only volumes.
Use distributed volumes only where redundancy is either not important, or is provided by other hardware or software layers. In other cases, use one of the volume types that provide redundancy, for example distributed-replicated volumes.
Limitations of distributed only volumes include:
  1. No in-service upgrades - distributed only volumes need to be taken offline during upgrades.
  2. Temporary inconsistencies of directory entries and inodes during eventual node failures.
  3. I/O operations will block or fail due to node unavailability or eventual node failures.
  4. Permanent loss of data.

Create a Distributed Volume

Use gluster volume create command to create different types of volumes, and gluster volume info command to verify successful volume creation.

Prerequisites

  1. Run the gluster volume create command to create the distributed volume.
    The syntax is gluster volume create NEW-VOLNAME [transport tcp | rdma (Deprecated) | tcp,rdma] NEW-BRICK...
    The default value for transport is tcp. Other options can be passed such as auth.allow or auth.reject. See Section 11.1, “Configuring Volume Options” for a full list of parameters.
    Red Hat recommends disabling the performance.client-io-threads option on distributed volumes, as this option tends to worsen performance. Run the following command to disable performance.client-io-threads:
    # gluster volume set VOLNAME performance.client-io-threads off

    Example 5.1. Distributed Volume with Two Storage Servers

    # gluster v create glustervol server1:/rhgs/brick1 server2:/rhgs/brick1
    volume create: glutervol: success: please start the volume to access data

    Example 5.2. Distributed Volume over InfiniBand with Four Servers

    # gluster v create glustervol transport rdma server1:/rhgs/brick1 server2:/rhgs/brick1 server3:/rhgs/brick1 server4:/rhgs/brick1
    volume create: glutervol: success: please start the volume to access data
  2. Run # gluster volume start VOLNAME to start the volume.
    # gluster v start glustervol
    volume start: glustervol: success
  3. Run gluster volume info command to optionally display the volume information.
    # gluster volume info
    Volume Name: test-volume
    Type: Distribute
    Status: Created
    Number of Bricks: 2
    Transport-type: tcp
    Bricks:
    Brick1: server1:/rhgs/brick
    Brick2: server2:/rhgs/brick

5.5. Creating Replicated Volumes

Replicated volume creates copies of files across multiple bricks in the volume. Use replicated volumes in environments where high-availability and high-reliability are critical.
Use gluster volume create to create different types of volumes, and gluster volume info to verify successful volume creation.
Prerequisites

Warning

Red Hat no longer recommends the use of two-way replication without arbiter bricks as Two-way replication without arbiter bricks is deprecated with Red Hat Gluster Storage 3.4 and no longer supported. This change affects both replicated and distributed-replicated volumes that do not use arbiter bricks.
Two-way replication without arbiter bricks is being deprecated because it does not provide adequate protection from split-brain conditions. Even in distributed-replicated configurations, two-way replication cannot ensure that the correct copy of a conflicting file is selected without the use of a tie-breaking node.
While a dummy node can be used as an interim solution for this problem, Red Hat strongly recommends that all volumes that currently use two-way replication without arbiter bricks are migrated to use either arbitrated replication or three-way replication.
Instructions for migrating a two-way replicated volume without arbiter bricks to an arbitrated replicated volume are available in the 5.7.5. Converting to an arbitrated volume. Information about three-way replication is available in Section 5.5.1, “Creating Three-way Replicated Volumes” and Section 5.6.1, “Creating Three-way Distributed Replicated Volumes”.

5.5.1. Creating Three-way Replicated Volumes

Three-way replicated volume creates three copies of files across multiple bricks in the volume. The number of bricks must be equal to the replica count for a replicated volume. To protect against server and disk failures, it is recommended that the bricks of the volume are from different servers.
Synchronous three-way replication is now fully supported in Red Hat Gluster Storage. It is recommended that three-way replicated volumes use JBOD, but use of hardware RAID with three-way replicated volumes is also supported.
Illustration of a Three-way Replicated Volume

Figure 5.2. Illustration of a Three-way Replicated Volume

Creating three-way replicated volumes
  1. Run the gluster volume create command to create the replicated volume.
    The syntax is # gluster volume create NEW-VOLNAME [replica COUNT] [transport tcp | rdma (Deprecated) | tcp,rdma] NEW-BRICK...
    The default value for transport is tcp. Other options can be passed such as auth.allow or auth.reject. See Section 11.1, “Configuring Volume Options” for a full list of parameters.

    Example 5.3. Replicated Volume with Three Storage Servers

    The order in which bricks are specified determines how bricks are replicated with each other. For example, every n bricks, where 3 is the replica count forms a replica set. This is illustrated in Figure 5.2, “Illustration of a Three-way Replicated Volume”.
    # gluster v create glutervol data replica 3 transport tcp server1:/rhgs/brick1 server2:/rhgs/brick2 server3:/rhgs/brick3
    volume create: glutervol: success: please start the volume to access
  2. Run # gluster volume start VOLNAME to start the volume.
    # gluster v start glustervol
    volume start: glustervol: success
  3. Run gluster volume info command to optionally display the volume information.

Important

By default, the client-side quorum is enabled on three-way replicated volumes to minimize split-brain scenarios. For more information on client-side quorum, see Section 11.15.1.2, “Configuring Client-Side Quorum”

5.5.2. Creating Sharded Replicated Volumes

Sharding breaks files into smaller pieces so that they can be distributed across the bricks that comprise a volume. This is enabled on a per-volume basis.
When sharding is enabled, files written to a volume are divided into pieces. The size of the pieces depends on the value of the volume's features.shard-block-size parameter. The first piece is written to a brick and given a GFID like a normal file. Subsequent pieces are distributed evenly between bricks in the volume (sharded bricks are distributed by default), but they are written to that brick's .shard directory, and are named with the GFID and a number indicating the order of the pieces. For example, if a file is split into four pieces, the first piece is named GFID and stored normally. The other three pieces are named GFID.1, GFID.2, and GFID.3 respectively. They are placed in the .shard directory and distributed evenly between the various bricks in the volume.
Because sharding distributes files across the bricks in a volume, it lets you store files with a larger aggregate size than any individual brick in the volume. Because the file pieces are smaller, heal operations are faster, and geo-replicated deployments can sync the small pieces of a file that have changed, rather than syncing the entire aggregate file.
Sharding also lets you increase volume capacity by adding bricks to a volume in an ad-hoc fashion.

5.5.2.1. Supported use cases

Sharding has one supported use case: in the context of providing Red Hat Gluster Storage as a storage domain for Red Hat Enterprise Virtualization, to provide storage for live virtual machine images. Note that sharding is also a requirement for this use case, as it provides significant performance improvements over previous implementations.

Important

Quotas are not compatible with sharding.

Important

Sharding is supported in new deployments only, as there is currently no upgrade path for this feature.

Example 5.4. Example: Three-way replicated sharded volume

  1. Before you start your volume, enable sharding on the volume.
    # gluster volume set test-volume features.shard enable
  2. Start the volume and ensure it is working as expected.
    # gluster volume test-volume start
    # gluster volume info test-volume

5.5.2.2. Configuration Options

Sharding is enabled and configured at the volume level. The configuration options are as follows.
features.shard
Enables or disables sharding on a specified volume. Valid values are enable and disable. The default value is disable.
# gluster volume set volname features.shard enable
Note that this only affects files created after this command is run; files created before this command is run retain their old behaviour.
features.shard-block-size
Specifies the maximum size of the file pieces when sharding is enabled. The supported value for this parameter is 512MB.
# gluster volume set volname features.shard-block-size 32MB
Note that this only affects files created after this command is run; files created before this command is run retain their old behaviour.

5.5.2.3. Finding the pieces of a sharded file

When you enable sharding, you might want to check that it is working correctly, or see how a particular file has been sharded across your volume.
To find the pieces of a file, you need to know that file's GFID. To obtain a file's GFID, run:
# getfattr -d -m. -e hex path_to_file
Once you have the GFID, you can run the following command on your bricks to see how this file has been distributed:
# ls /rhgs/*/.shard -lh | grep GFID

5.6. Creating Distributed Replicated Volumes

Use distributed replicated volumes in environments where the requirement to scale storage, and high-reliability is critical. Distributed replicated volumes also offer improved read performance in most environments.

Note

The number of bricks must be a multiple of the replica count for a distributed replicated volume. Also, the order in which bricks are specified has a great effect on data protection. Each replica_count consecutive bricks in the list you give will form a replica set, with all replica sets combined into a distribute set. To ensure that replica-set members are not placed on the same node, list the first brick on every server, then the second brick on every server in the same order, and so on.
Prerequisites

5.6.1. Creating Three-way Distributed Replicated Volumes

Three-way distributed replicated volume distributes and creates three copies of files across multiple bricks in the volume. The number of bricks must be equal to the replica count for a replicated volume. To protect against server and disk failures, it is recommended that the bricks of the volume are from different servers.
Synchronous three-way distributed replication is now fully supported in Red Hat Gluster Storage. It is recommended that three-way distributed replicated volumes use JBOD, but use of hardware RAID with three-way distributed replicated volumes is also supported.
Illustration of a Three-way Distributed Replicated Volume

Figure 5.3. Illustration of a Three-way Distributed Replicated Volume

Creating three-way distributed replicated volumes
  1. Run the gluster volume create command to create the distributed replicated volume.
    The syntax is # gluster volume create NEW-VOLNAME [replica COUNT] [transport tcp | rdma (Deprecated) | tcp,rdma] NEW-BRICK...
    The default value for transport is tcp. Other options can be passed such as auth.allow or auth.reject. See Section 11.1, “Configuring Volume Options” for a full list of parameters.

    Example 5.5. Six Node Distributed Replicated Volume with a Three-way Replication

    The order in which bricks are specified determines how bricks are replicated with each other. For example, first 3 bricks, where 3 is the replica count forms a replicate set.
    # gluster v create glustervol replica 3 transport tcp server1:/rhgs/brick1 server2:/rhgs/brick1 server3:/rhgs/brick1 server4:/rhgs/brick1 server5:/rhgs/brick1 server6:/rhgs/brick1
    volume create: glutervol: success: please start the volume to access data
  2. Run # gluster volume start VOLNAME to start the volume.
    # gluster v start glustervol
    volume start: glustervol: success
  3. Run gluster volume info command to optionally display the volume information.

Important

By default, the client-side quorum is enabled on three-way distributed replicated volumes. You must also set server-side quorum on the distributed-replicated volumes to prevent split-brain scenarios. For more information on setting quorums, see Section 11.15.1, “Preventing Split-brain”.

5.7. Creating Arbitrated Replicated Volumes

An arbitrated replicated volume contains two full copies of the files in the volume. Arbitrated volumes have an extra arbiter brick for every two data bricks in the volume. Arbiter bricks do not store file data; they only store file names, structure, and metadata. Arbiter bricks use client quorum to compare metadata on the arbiter with the metadata of the other nodes to ensure consistency in the volume and prevent split-brain conditions.

Advantages of arbitrated replicated volumes

Better consistency
When an arbiter is configured, arbitration logic uses client-side quorum in auto mode to prevent file operations that would lead to split-brain conditions.
Less disk space required
Because an arbiter brick only stores file names and metadata, an arbiter brick can be much smaller than the other bricks in the volume.
Fewer nodes required
The node that contains the arbiter brick of one volume can be configured with the data brick of another volume. This "chaining" configuration allows you to use fewer nodes to fulfill your overall storage requirements.
Easy migration from deprecated two-way replicated volumes
Red Hat Gluster Storage can convert a two-way replicated volume without arbiter bricks into an arbitrated replicated volume. See Section 5.7.5, “Converting to an arbitrated volume” for details.

Limitations of arbitrated replicated volumes

  • Arbitrated replicated volumes provide better data consistency than a two-way replicated volume that does not have arbiter bricks. However, because arbitrated replicated volumes store only metadata, they provide the same level of availability as a two-way replicated volume that does not have arbiter bricks. To achieve high-availability, you need to use a three-way replicated volume instead of an arbitrated replicated volume.
  • Tiering is not compatible with arbitrated replicated volumes.
  • Arbitrated volumes can only be configured in sets of three bricks at a time. Red Hat Gluster Storage can convert an existing two-way replicated volume without arbiter bricks into an arbitrated replicated volume by adding an arbiter brick to that volume. See Section 5.7.5, “Converting to an arbitrated volume” for details.

5.7.1. Arbitrated volume requirements

This section outlines the requirements of a supported arbitrated volume deployment.

5.7.1.1. System requirements for nodes hosting arbiter bricks

The minimum system requirements for a node that contains an arbiter brick differ depending on the configuration choices made by the administrator. See Section 5.7.4, “Creating multiple arbitrated replicated volumes across fewer total nodes” for details about the differences between the dedicated arbiter and chained arbiter configurations.

Table 5.1. Requirements for arbitrated configurations on physical machines

Configuration typeMin CPUMin RAMNICArbiter Brick SizeMax Latency
Dedicated arbiter64-bit quad-core processor with 2 sockets8 GB[a]Match to other nodes in the storage pool1 TB to 4 TB[b]5 ms[c]
Chained arbiterMatch to other nodes in the storage pool1 TB to 4 TB[d]5 ms[e]
[a] More RAM may be necessary depending on the combined capacity of the number of arbiter bricks on the node.
[b] Arbiter and data bricks can be configured on the same device provided that the data and arbiter bricks belong to different replica sets. See Section 5.7.1.2, “Arbiter capacity requirements” for further details on sizing arbiter volumes.
[c] This is the maximum round trip latency requirement between all nodes irrespective of Aribiter node. See KCS#413623 to know how to determine latency between nodes.
[d] Multiple bricks can be created on a single RAIDed physical device. Please refer the following product documentation: Section 19.2, “Brick Configuration”
[e] This is the maximum round trip latency requirement between all nodes irrespective of Aribiter node. See KCS#413623 to know how to determine latency between nodes.
The requirements for arbitrated configurations on virtual machines are:
  • minimum 4 vCPUs
  • minimum 16 GB RAM
  • 1 TB to 4 TB of virtual disk space
  • maximum 5 ms latency

5.7.1.2. Arbiter capacity requirements

Because an arbiter brick only stores file names and metadata, an arbiter brick can be much smaller than the other bricks in the volume or replica set. The required size for an arbiter brick depends on the number of files being stored on the volume.
The recommended minimum arbiter brick size can be calculated with the following formula:
minimum arbiter brick size = 4 KB * ( size in KB of largest data brick in volume or replica set / average file size in KB)
For example, if you have two 1 TB data bricks, and the average size of the files is 2 GB, then the recommended minimum size for your arbiter brick 2 MB, as shown in the following example:
minimum arbiter brick size  = 4 KB * ( 1 TB / 2 GB )
                            = 4 KB * ( 1000000000 KB / 2000000 KB )
                            = 4 KB * 500 KB
                            = 2000 KB
                            = 2 MB
If sharding is enabled, and your shard-block-size is smaller than the average file size in KB, then you need to use the following formula instead, because each shard also has a metadata file:
minimum arbiter brick size = 4 KB * ( size in KB of largest data brick in volume or replica set / shard block size in KB )
Alternatively, if you know how many files you will store in a volume, the recommended minimum arbiter brick size is the maximum number of files multiplied by 4 KB. For example, if you expect to have 200,000 files on your volume, your arbiter brick should be at least 800,000 KB, or 0.8 GB, in size.
Red Hat also recommends overprovisioning where possible so that there is no short-term need to increase the size of the arbiter brick. Also, refer to Brick Configuration for more information on usage of maxpct.

5.7.2. Arbitration logic

In an arbitrated volume, whether a file operation is permitted depends on the current state of the bricks in the volume. The following table describes arbitration behavior in all possible volume states.

Table 5.2. Allowed operations for current volume state

Volume stateArbitration behavior
All bricks availableAll file operations permitted.
Arbiter and 1 data brick available
If the arbiter does not agree with the available data node, write operations fail with ENOTCONN (since the brick that is correct is not available). Other file operations are permitted.
If the arbiter's metadata agrees with the available data node, all file operations are permitted.
Arbiter down, data bricks availableAll file operations are permitted. The arbiter's records are healed when it becomes available.
Only one brick available
All file operations fail with ENOTCONN.

5.7.3. Creating an arbitrated replicated volume

The command for creating an arbitrated replicated volume has the following syntax:
# gluster volume create VOLNAME replica 3 arbiter 1 HOST1:DATA_BRICK1 HOST2:DATA_BRICK2 HOST3:ARBITER_BRICK3
This creates a volume with one arbiter for every three replicate bricks. The arbiter is the last brick in every set of three bricks.

Note

The syntax of this command is misleading. There are a total of 3 bricks in this set. This command creates a volume with two bricks that replicate all data and one arbiter brick that replicates only metadata.
In the following example, the bricks on server3 and server6 are the arbiter bricks. Note that because multiple sets of three bricks are provided, this creates a distributed replicated volume with arbiter bricks.
# gluster volume create testvol replica 3 arbiter 1 \
server1:/bricks/brick server2:/bricks/brick server3:/bricks/arbiter_brick \
server4:/bricks/brick server5:/bricks/brick server6:/bricks/arbiter_brick
# gluster volume info testvol
Volume Name: testvol
Type: Distributed-Replicate
Volume ID: ed9fa4d5-37f1-49bb-83c3-925e90fab1bc
Status: Created
Snapshot Count: 0
Number of Bricks: 2 x (2 + 1) = 6
Transport-type: tcp
Bricks:
Brick1: server1:/bricks/brick
Brick2: server2:/bricks/brick
Brick3: server3:/bricks/arbiter_brick (arbiter)
Brick1: server4:/bricks/brick
Brick2: server5:/bricks/brick
Brick3: server6:/bricks/arbiter_brick (arbiter)
Options Reconfigured:
cluster.granular-entry-heal: on
transport.address-family: inet
performance.readdir-ahead: on
nfs.disable: on

5.7.4. Creating multiple arbitrated replicated volumes across fewer total nodes

If you are configuring more than one arbitrated-replicated volume, or a single volume with multiple replica sets, you can use fewer nodes in total by using either of the following techniques:
  • Chain multiple arbitrated replicated volumes together, by placing the arbiter brick for one volume on the same node as a data brick for another volume. Chaining is useful for write-heavy workloads when file size is closer to metadata file size (that is, from 32–128 KiB). This avoids all metadata I/O going through a single disk.
    In arbitrated distributed-replicated volumes, you can also place an arbiter brick on the same node as another replica sub-volume's data brick, since these do not share the same data.
  • Place the arbiter bricks from multiple volumes on a single dedicated node. A dedicated arbiter node is suited to write-heavy workloads with larger files, and read-heavy workloads.

Example 5.6. Example of a dedicated configuration

The following commands create two arbitrated replicated volumes, firstvol and secondvol. Server3 contains the arbiter bricks of both volumes.
# gluster volume create firstvol replica 3 arbiter 1 server1:/bricks/brick server2:/bricks/brick server3:/bricks/arbiter_brick
# gluster volume create secondvol replica 3 arbiter 1 server4:/bricks/data_brick server5:/bricks/brick server3:/bricks/brick
Dedicated Arbiter Node Configuration
Two gluster volumes configured across five servers to create two three-way arbitrated replicated volumes, with the arbiter bricks on a dedicated arbiter node.

Example 5.7. Example of a chained configuration

The following command configures an arbitrated replicated volume with six sub-volumes chained across six servers in a 6 x (2 + 1) configuration.
# gluster volume create arbrepvol replica 3 arbiter 1 server1:/bricks/brick1 server2:/bricks/brick1 server3:/bricks/arbiter_brick1 server2:/bricks/brick2 server3:/bricks/brick2 server4:/bricks/arbiter_brick2 server3:/bricks/brick3 server4:/bricks/brick3 server5:/bricks/arbiter_brick3 server4:/bricks/brick4 server5:/bricks/brick4 server6:/bricks/arbiter_brick4 server5:/bricks/brick5 server6:/bricks/brick5 server1:/bricks/arbiter_brick5 server6:/bricks/brick6 server1:/bricks/brick6 server2:/bricks/arbiter_brick6
6 x (2 + 1) Arbitrated Distributed-Replicated Configuration
Six replicated gluster sub-volumes chained across six servers to create a 6 * (2 + 1) arbitrated distributed-replicated configuration.

5.7.5. Converting to an arbitrated volume

You can convert a replicated volume into an arbitrated volume by adding new arbiter bricks for each replicated sub-volume, or replacing replica bricks with arbiter bricks.

Procedure 5.1. Converting a replica 2 volume to an arbitrated volume

Warning

Do not perform this process if geo-replication is configured. There is a race condition tracked by Bug 1683893 that means data can be lost when converting a volume if geo-replication is enabled.
  1. Verify that healing is not in progress

    # gluster volume heal VOLNAME info
    Wait until pending heal entries is 0 before proceeding.
  2. Disable and stop self-healing

    Run the following commands to disable data, metadata, and entry self-heal, and the self-heal daemon.
    # gluster volume set VOLNAME cluster.data-self-heal off
    # gluster volume set VOLNAME cluster.metadata-self-heal off
    # gluster volume set VOLNAME cluster.entry-self-heal off
    # gluster volume set VOLNAME self-heal-daemon off
  3. Add arbiter bricks to the volume

    Convert the volume by adding an arbiter brick for each replicated sub-volume.
    # gluster volume add-brick VOLNAME replica 3 arbiter 1 HOST:arbiter-brick-path
    For example, if you have an existing two-way replicated volume called testvol, and a new brick for the arbiter to use, you can add a brick as an arbiter with the following command:
    # gluster volume add-brick testvol replica 3 arbiter 1 server:/bricks/arbiter_brick
    If you have an existing two-way distributed-replicated volume, you need a new brick for each sub-volume in order to convert it to an arbitrated distributed-replicated volume, for example:
    # gluster volume add-brick testvol replica 3 arbiter 1 server1:/bricks/arbiter_brick1 server2:/bricks/arbiter_brick2
  4. Wait for client volfiles to update

    This takes about 5 minutes.
  5. Verify that bricks added successfully

    # gluster volume info VOLNAME
    # gluster volume status VOLNAME
  6. Re-enable self-healing

    Run the following commands to re-enable self-healing on the servers.
    # gluster volume set VOLNAME cluster.data-self-heal on
    # gluster volume set VOLNAME cluster.metadata-self-heal on
    # gluster volume set VOLNAME cluster.entry-self-heal on
    # gluster volume set VOLNAME self-heal-daemon on
  7. Verify all entries are healed

    # gluster volume heal VOLNAME info
    Wait until pending heal entries is 0 to ensure that all heals completed successfully.

Procedure 5.2. Converting a replica 3 volume to an arbitrated volume

Warning

Do not perform this process if geo-replication is configured. There is a race condition tracked by Bug 1683893 that means data can be lost when converting a volume if geo-replication is enabled.
  1. Verify that healing is not in progress

    # gluster volume heal VOLNAME info
    Wait until pending heal entries is 0 before proceeding.
  2. Reduce the replica count of the volume to 2

    Remove one brick from every sub-volume in the volume so that the replica count is reduced to 2. For example, in a replica 3 volume that distributes data across 2 sub-volumes, run the following command:
    # gluster volume remove-brick VOLNAME replica 2 HOST:subvol1-brick-path HOST:subvol2-brick-path force

    Note

    In a distributed replicated volume, data is distributed across sub-volumes, and replicated across bricks in a sub-volume. This means that to reduce the replica count of a volume, you need to remove a brick from every sub-volume.
    Bricks are grouped by sub-volume in the gluster volume info output. If the replica count is 3, the first 3 bricks form the first sub-volume, the next 3 bricks form the second sub-volume, and so on.
    # gluster volume info VOLNAME
    [...]
    Number of Bricks: 2 x 3 = 6
    Transport-type: tcp
    Bricks:
    Brick1: node1:/test1/brick
    Brick2: node2:/test2/brick
    Brick3: node3:/test3/brick
    Brick4: node1:/test4/brick
    Brick5: node2:/test5/brick
    Brick6: node3:/test6/brick
    [...]
    In this volume, data is distributed across two sub-volumes, which each consist of three bricks. The first sub-volume consists of bricks 1, 2, and 3. The second sub-volume consists of bricks 4, 5, and 6. Removing any one brick from each subvolume using the following command reduces the replica count to 2 as required.
    # gluster volume remove-brick VOLNAME replica 2 HOST:subvol1-brick-path HOST:subvol2-brick-path force
  3. Disable and stop self-healing

    Run the following commands to disable data, metadata, and entry self-heal, and the self-heal daemon.
    # gluster volume set VOLNAME cluster.data-self-heal off
    # gluster volume set VOLNAME cluster.metadata-self-heal off
    # gluster volume set VOLNAME cluster.entry-self-heal off
    # gluster volume set VOLNAME self-heal-daemon off
  4. Add arbiter bricks to the volume

    Convert the volume by adding an arbiter brick for each replicated sub-volume.
    # gluster volume add-brick VOLNAME replica 3 arbiter 1 HOST:arbiter-brick-path
    For example, if you have an existing replicated volume:
    # gluster volume add-brick testvol replica 3 arbiter 1 server:/bricks/brick
    If you have an existing distributed-replicated volume:
    # gluster volume add-brick testvol replica 3 arbiter 1 server1:/bricks/arbiter_brick1 server2:/bricks/arbiter_brick2
  5. Wait for client volfiles to update

    This takes about 5 minutes. Verify that this is complete by running the following command on each client.
    # grep -ir connected mount-path/.meta/graphs/active/volname-client-*/private
    The number of times connected=1 appears in the output is the number of bricks connected to the client.
  6. Verify that bricks added successfully

    # gluster volume info VOLNAME
    # gluster volume status VOLNAME
  7. Re-enable self-healing

    Run the following commands to re-enable self-healing on the servers.
    # gluster volume set VOLNAME cluster.data-self-heal on
    # gluster volume set VOLNAME cluster.metadata-self-heal on
    # gluster volume set VOLNAME cluster.entry-self-heal on
    # gluster volume set VOLNAME self-heal-daemon on
  8. Verify all entries are healed

    # gluster volume heal VOLNAME info
    Wait until pending heal entries is 0 to ensure that all heals completed successfully.

5.7.6. Converting an arbitrated volume to a three-way replicated volume

You can convert an arbitrated volume into a three-way replicated volume or a three-way distributed replicated volume by replacing the arbiter bricks with full bricks for each replicated sub-volume.

Warning

Do not perform this process if geo-replication is configured. There is a race condition tracked by Bug 1683893 that means data can be lost when converting a volume if geo-replication is enabled.

Procedure 5.3. Converting an arbitrated volume to a replica 3 volume

  1. Verify that healing is not in progress

    # gluster volume heal VOLNAME info
    Wait until pending heal entries is 0 before proceeding.
  2. Remove arbiter bricks from the volume

    Check which bricks are listed as (arbiter), and then remove those bricks from the volume.
    # gluster volume info VOLNAME
    # gluster volume remove-brick VOLNAME replica 2 HOST:arbiter-brick-path force
  3. Disable and stop self-healing

    Run the following commands to disable data, metadata, and entry self-heal, and the self-heal daemon.
    # gluster volume set VOLNAME cluster.data-self-heal off
    # gluster volume set VOLNAME cluster.metadata-self-heal off
    # gluster volume set VOLNAME cluster.entry-self-heal off
    # gluster volume set VOLNAME self-heal-daemon off
  4. Add full bricks to the volume

    Convert the volume by adding a brick for each replicated sub-volume.
    # gluster volume add-brick VOLNAME replica 3 HOST:brick-path
    For example, if you have an existing arbitrated replicated volume:
    # gluster volume add-brick testvol replica 3 server:/bricks/brick
    If you have an existing arbitrated distributed-replicated volume:
    # gluster volume add-brick testvol replica 3 server1:/bricks/brick1 server2:/bricks/brick2
  5. Wait for client volfiles to update

    This takes about 5 minutes.
  6. Verify that bricks added successfully

    # gluster volume info VOLNAME
    # gluster volume status VOLNAME
  7. Re-enable self-healing

    Run the following commands to re-enable self-healing on the servers.
    # gluster volume set VOLNAME cluster.data-self-heal on
    # gluster volume set VOLNAME cluster.metadata-self-heal on
    # gluster volume set VOLNAME cluster.entry-self-heal on
    # gluster volume set VOLNAME self-heal-daemon on
  8. Verify all entries are healed

    # gluster volume heal VOLNAME info
    Wait until pending heal entries is 0 to ensure that all heals completed successfully.

5.7.7. Tuning recommendations for arbitrated volumes

Red Hat recommends the following when arbitrated volumes are in use:
  • For dedicated arbiter nodes, use JBOD for arbiter bricks, and RAID6 for data bricks.
  • For chained arbiter volumes, use the same RAID6 drive for both data and arbiter bricks.
See Chapter 19, Tuning for Performance for more information on enhancing performance that is not specific to the use of arbiter volumes.

5.8. Creating Dispersed Volumes

Dispersed volumes are based on erasure coding. Erasure coding (EC) is a method of data protection in which data is broken into fragments, expanded and encoded with redundant data pieces and stored across a set of different locations. This allows the recovery of the data stored on one or more bricks in case of failure. The number of bricks that can fail without losing data is configured by setting the redundancy count.
Dispersed volume requires less storage space when compared to a replicated volume. It is equivalent to a replicated pool of size two, but requires 1.5 TB instead of 2 TB to store 1 TB of data when the redundancy level is set to 2. In a dispersed volume, each brick stores some portions of data and parity or redundancy. The dispersed volume sustains the loss of data based on the redundancy level.

Important

Dispersed volume configuration is supported only on JBOD storage. For more information, see Section 19.1.2, “JBOD”.
Illustration of a Dispersed Volume

Figure 5.4. Illustration of a Dispersed Volume

The data protection offered by erasure coding can be represented in simple form by the following equation: n = k + m. Here n is the total number of bricks, we would require any k bricks out of n bricks for recovery. In other words, we can tolerate failure up to any m bricks. With this release, the following configurations are supported:
  • 6 bricks with redundancy level 2 (4 + 2)
  • 10 bricks with redundancy level 2 (8 + 2)
  • 11 bricks with redundancy level 3 (8 + 3)
  • 12 bricks with redundancy level 4 (8 + 4)
  • 20 bricks with redundancy level 4 (16 + 4)
For optimal fault tolerance, create each brick on a separate server. Creating multiple bricks on a single server is supported, but the more bricks there are on a single server, the greater the risk to availability and consistency when that single server becomes unavailable.
Use gluster volume create to create different types of volumes, and gluster volume info to verify successful volume creation.
Prerequisites

Important

Red Hat recommends you to review the Dispersed Volume configuration recommendations explained in Section 5.8, “Creating Dispersed Volumes” before creating the Dispersed volume.
To Create a dispersed volume
  1. Run the gluster volume create command to create the dispersed volume.
    The syntax is # gluster volume create NEW-VOLNAME [disperse-data COUNT] [redundancy COUNT] [transport tcp | rdma (Deprecated) | tcp,rdma] NEW-BRICK...
    The number of bricks required to create a disperse volume is the sum of disperse-data count and redundancy count.
    The disperse-data count option specifies the number of bricks that is part of the dispersed volume, excluding the count of the redundant bricks. For example, if the total number of bricks is 6 and redundancy-count is specified as 2, then the disperse-data count is 4 (6 - 2 = 4). If the disperse-data count option is not specified, and only the redundancy count option is specified, then the disperse-data count is computed automatically by deducting the redundancy count from the specified total number of bricks.
    Redundancy determines how many bricks can be lost without interrupting the operation of the volume. If redundancy count is not specified, based on the configuration it is computed automatically to the optimal value and a warning message is displayed.
    The default value for transport is tcp. Other options can be passed such as auth.allow or auth.reject. See Section 5.2, “About Encrypted Disk” for a full list of parameters.

    Example 5.8. Dispersed Volume with Six Storage Servers

    # gluster v create glustervol disperse-data 4 redundancy 2 transport tcp server1:/rhgs1/brick1 server2:/rhgs2/brick2 server3:/rhgs3/brick3 server4:/rhgs4/brick4 server5:/rhgs5/brick5 server6:/rhgs6/brick6
    volume create: glutervol: success: please start the volume to access data
  2. Run # gluster volume start VOLNAME to start the volume.
    # gluster v start glustervol
    volume start: glustervol: success

    Important

    The open-behind volume option is enabled by default. If you are accessing the dispersed volume using the SMB protocol, you must disable the open-behind volume option to avoid performance bottleneck on large file workload. Run the following command to disable open-behind volume option:
    # gluster volume set VOLNAME open-behind off
    For information on open-behind volume option, see Section 11.1, “Configuring Volume Options”
  3. Run gluster volume info command to optionally display the volume information.

5.9. Creating Distributed Dispersed Volumes

Distributed dispersed volumes support the same configurations of erasure coding as dispersed volumes. The number of bricks in a distributed dispersed volume must be a multiple of (K+M). With this release, the following configurations are supported:
  • Multiple disperse sets containing 6 bricks with redundancy level 2
  • Multiple disperse sets containing 10 bricks with redundancy level 2
  • Multiple disperse sets containing 11 bricks with redundancy level 3
  • Multiple disperse sets containing 12 bricks with redundancy level 4
  • Multiple disperse sets containing 20 bricks with redundancy level 4

Important

Distributed dispersed volume configuration is supported only on JBOD storage. For more information, see Section 19.1.2, “JBOD”.
Use gluster volume create to create different types of volumes, and gluster volume info to verify successful volume creation.
Prerequisites
Illustration of a Distributed Dispersed Volume

Figure 5.5. Illustration of a Distributed Dispersed Volume

Creating distributed dispersed volumes

Important

Red Hat recommends you to review the Distributed Dispersed Volume configuration recommendations explained in Section 11.16, “Recommended Configurations - Dispersed Volume” before creating the Distributed Dispersed volume.
  1. Run the gluster volume create command to create the dispersed volume.
    The syntax is # gluster volume create NEW-VOLNAME disperse-data COUNT [redundancy COUNT] [transport tcp | rdma (Deprecated) | tcp,rdma] NEW-BRICK...
    The default value for transport is tcp. Other options can be passed such as auth.allow or auth.reject. See Section 11.1, “Configuring Volume Options” for a full list of parameters.

    Example 5.9. Distributed Dispersed Volume with Six Storage Servers

    # gluster v create glustervol disperse-data 4 redundancy 2 transport tcp server1:/rhgs1/brick1 server2:/rhgs2/brick2 server3:/rhgs3/brick3 server4:/rhgs4/brick4 server5:/rhgs5/brick5 server6:/rhgs6/brick6 server1:/rhgs7/brick7 server2:/rhgs8/brick8 server3:/rhgs9/brick9 server4:/rhgs10/brick10 server5:/rhgs11/brick11 server6:/rhgs12/brick12
    volume create: glutervol: success: please start the volume to access data.
    The above example is illustrated in Figure 5.4, “Illustration of a Dispersed Volume” . In the illustration and example, you are creating 12 bricks from 6 servers.
  2. Run # gluster volume start VOLNAME to start the volume.
    # gluster v start glustervol
    volume start: glustervol: success

    Important

    The open-behind volume option is enabled by default. If you are accessing the distributed dispersed volume using the SMB protocol, you must disable the open-behind volume option to avoid performance bottleneck on large file workload. Run the following command to disable open-behind volume option:
    # gluster volume set VOLNAME open-behind off
    For information on open-behind volume option, see Section 11.1, “Configuring Volume Options”
  3. Run gluster volume info command to optionally display the volume information.

5.10. Starting Volumes

Volumes must be started before they can be mounted.
To start a volume, run # gluster volume start VOLNAME
For example, to start test-volume:
# gluster v start glustervol
volume start: glustervol: success

Chapter 6. Creating Access to Volumes

Warning

Do not enable the storage.fips-mode-rchecksum volume option on volumes with clients that use Red Hat Gluster Storage 3.4 or earlier.
Red Hat Gluster Storage volumes can be accessed using a number of technologies:

6.1. Client Support Information

6.1.1. Cross Protocol Data Access

Because of differences in locking semantics, a single Red Hat Gluster Storage volume cannot be concurrently accessed by multiple protocols. Current support for concurrent access is defined in the following table.

Table 6.1. Cross Protocol Data Access Matrix

  SMB Gluster NFS NFS-Ganesha Native FUSE Object
SMB Yes No No No No
Gluster NFS (Deprecated) No Yes No No No
NFS-Ganesha No No Yes No No
Native FUSE No No No Yes Yes [a]

6.1.2. Client Operating System Protocol Support

The following table describes the support level for each file access protocol in a supported client operating system.

Table 6.2. Client OS Protocol Support

Client OSFUSEGluster NFSNFS-GaneshaSMB
RHEL 5UnsupportedUnsupportedUnsupportedUnsupported
RHEL 6SupportedDeprecatedUnsupportedSupported
RHEL 7SupportedDeprecatedSupportedSupported
RHEL 8SupportedUnsupportedSupportedSupported
Windows Server 2008, 2012, 2016UnsupportedUnsupportedUnsupportedSupported
Windows 7, 8, 10UnsupportedUnsupportedUnsupportedSupported
Mac OS 10.15UnsupportedUnsupportedUnsupportedSupported

6.1.3. Transport Protocol Support

The following table provides the support matrix for the supported access protocols with TCP/RDMA.

Table 6.3. Transport Protocol Support

Access Protocols TCP RDMA (Deprecated)
FUSEYes Yes
SMB Yes No
NFSYesYes

Warning

Using RDMA as a transport protocol is considered deprecated in Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support it on new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.

Important

Red Hat Gluster Storage requires certain ports to be open. You must ensure that the firewall settings allow access to the ports listed at Chapter 3, Considerations for Red Hat Gluster Storage.
Gluster user is created as a part of gluster installation. The purpose of gluster user is to provide privileged access to libgfapi based application (for example, nfs-ganesha and glusterfs-coreutils ). For a normal user of an application, write access to statedump directory is restricted. As a result, attempting to write a state dump to this directory fails. Privileged access is needed by these applications in order to be able to write to the statedump directory. In order to write to this location, the user that runs the application should ensure that the application is added to the gluster user group. After the application is added, restart gluster processes to apply the new group.

6.2. Native Client

Native Client is a FUSE-based client running in user space. Native Client is the recommended method for accessing Red Hat Gluster Storage volumes when high concurrency and high write performance is required.
This section introduces Native Client and describes how to perform the following:
  • Install Native Client packages
  • Mount Red Hat Gluster Storage volumes (manually and automatically)
  • Verify that the Gluster Storage volume has mounted successfully

Note

  • Red Hat Gluster Storage server supports the Native Client version which is the same as the server version and the preceding version of Native Client . For list of releases see: https://access.redhat.com/solutions/543123.
  • From Red Hat Gluster Storage 3.5 batch update 7 onwards, glusterfs-6.0-62 and higher version of glusterFS Native Client is only available via rh-gluster-3-client-for-rhel-8-x86_64-rpms for Red Hat Gluster Storage based on Red Hat Enterprise Enterprise Linux (RHEL 8) and rh-gluster-3-client-for-rhel-7-server-rpms for Red Hat Gluster Storage based on RHEL 7.

Table 6.4. Red Hat Gluster Storage Support Matrix

Red Hat Enterprise Linux version Red Hat Gluster Storage version Native client version
6.5 3.0 3.0, 2.1*
6.6 3.0.2, 3.0.3, 3.0.4 3.0, 2.1*
6.73.1, 3.1.1, 3.1.23.1, 3.0, 2.1*
6.83.1.33.1.3
6.93.23.2, 3.1.3*
6.93.33.3, 3.2
6.93.3.13.3.1, 3.3, 3.2
6.103.43.5*, 3.4, 3.3.z
7.13.1, 3.1.13.1.1, 3.1, 3.0
7.23.1.23.1.2, 3.1, 3.0
7.23.1.33.1.3
7.33.23.2, 3.1.3
7.43.23.2, 3.1.3
7.43.33.3, 3.2
7.43.3.13.3.1, 3.3, 3.2
7.53.3.1, 3.43.3.z, 3.4.z
7.63.3.1, 3.43.3.z, 3.4.z
7.73.5.13.4.z, 3.5.z
7.83.5.23.4.z, 3.5.z
7.93.5.3, 3.5.4, 3.5.5, 3.5.6, 3.5.73.4.z, 3.5.z
8.1NA3.5
8.23.5.23.5.z
8.33.5.33.5.z
8.43.5.43.5.z
8.53.5.5, 3.5.63.5.z
8.63.5.73.5.z

Warning

Red Hat Gluster Storage 3.5 supports RHEL 6.x using Native Client 3.5.

Warning

  • For Red Hat Gluster Storage 3.5, Red Hat supports only Red Hat Gluster Storage 3.4 and 3.5 clients.
For more information on the release version see, https://access.redhat.com/solutions/543123.

6.2.1. Installing Native Client

After installing the client operating system, register the target system to Red Hat Network and subscribe to the Red Hat Enterprise Linux Server channel. There are two ways to register and subscribe a system to Red Hat Subscription Management:
  • Use the Command Line to Register and Subscribe a System to Red Hat Subscription Management
  • Use the Web Interface to Register and Subscribe a System to Red Hat Subscription Management

Important

All clients must be of the same version. Red Hat strongly recommends upgrading the servers before upgrading the clients.

Use the Command Line to Register and Subscribe a System to Red Hat Subscription Management

Register the system using the command line, and subscribe to the correct repositories.

Prerequisites

  • Know the user name and password of the Red Hat Subscription Manager account with Red Hat Gluster Storage entitlements.
  1. Run the subscription-manager register command to list the available pools. Select the appropriate pool and enter your Red Hat Subscription Manager user name and password to register the system with Red Hat Subscription Manager.
    # subscription-manager register
  2. Depending on your client, run one of the following commands to subscribe to the correct repositories.
    • For Red Hat Enterprise Linux 8 clients:
      # subscription-manager repos --enable=rh-gluster-3-client-for-rhel-8-x86_64-rpms
    • For Red Hat Enterprise Linux 7.x clients:
      # subscription-manager repos --enable=rhel-7-server-rpms --enable=rh-gluster-3-client-for-rhel-7-server-rpms

      Note

      The following command can also be used, but Red Hat Gluster Storage may deprecate support for this repository in future releases.
      # subscription-manager repos --enable=rhel-7-server-rh-common-rpms
    • For Red Hat Enterprise Linux 6.1 and later clients:
      # subscription-manager repos --enable=rhel-6-server-rpms --enable=rhel-6-server-rhs-client-1-rpms
    For more information on subscriptions, refer to Section 3.1 Registering and attaching a system from the Command Line in Using and Configuring Red Hat Subscription Management.
  3. Verify that the system is subscribed to the required repositories.
    # yum repolist

Use the Web Interface to Register and Subscribe a System to Red Hat Subscription Management

Register the system using the web interface, and subscribe to the correct channels.

Prerequisites

  • Know the user name and password of the Red Hat Subsrciption Management (RHSM) account with Red Hat Gluster Storage entitlements.
  1. Log on to Red Hat Subscription Management (https://access.redhat.com/management).
  2. Click the Systems link at the top of the screen.
  3. Click the name of the system to which the Red Hat Gluster Storage Native Client channel must be appended.
  4. Click Alter Channel Subscriptions in the Subscribed Channels section of the screen.
  5. Expand the node for Additional Services Channels for Red Hat Enterprise Linux 7 for x86_64 or for x86_64 or for Red Hat Enterprise Linux 5 for x86_64 depending on the client platform.
  6. Click the Change Subscriptions button to finalize the changes.
    When the page refreshes, select the Details tab to verify the system is subscribed to the appropriate channels.

Install Native Client Packages

Install Native Client packages from Red Hat Network
  1. Run the yum install command to install the native client RPM packages.
    # yum install glusterfs glusterfs-fuse
  2. For Red Hat Enterprise 5.x client systems, run the modprobe command to load FUSE modules before mounting Red Hat Gluster Storage volumes.
    # modprobe fuse
    For more information on loading modules at boot time, see https://access.redhat.com/knowledge/solutions/47028 .

6.2.2. Upgrading Native Client

Before updating the Native Client, subscribe the clients to the channels mentioned in Section 6.2.1, “Installing Native Client”
  1. Unmount gluster volumes

    Unmount any gluster volumes prior to upgrading the native client.
    # umount /mnt/glusterfs
  2. Upgrade the client

    Run the yum update command to upgrade the native client:
    # yum update glusterfs glusterfs-fuse
  3. Remount gluster volumes

6.2.3. Mounting Red Hat Gluster Storage Volumes

After installing Native Client, the Red Hat Gluster Storage volumes must be mounted to access data. Three methods are available:
After mounting a volume, test the mounted volume using the procedure described in Section 6.2.3.5, “Testing Mounted Volumes”.

Note

  • Clients should be on the same version as the server, and at least on the version immediately previous to the server version. For Red Hat Gluster Storage 3.5, the recommended native client version should either be 3.4.z, and 3.5. For other versions, see Section 6.2, “Native Client”.
  • Server names selected during volume creation should be resolvable in the client machine. Use appropriate /etc/hosts entries, or a DNS server to resolve server names to IP addresses.
  • Internet Protocol Version 6 (IPv6) support is available only for Red Hat Hyperconverged Infrastructure for Virtualization environments and not for Red Hat Gluster Storage standalone environments.

6.2.3.1. Mount Commands and Options

The following options are available when using the mount -t glusterfs command. All options must be separated with commas.
# mount -t glusterfs -o backup-volfile-servers=volfile_server2:volfile_server3:.... ..:volfile_serverN,transport-type tcp,log-level=WARNING,reader-thread-count=2,log-file=/var/log/gluster.log server1:/test-volume /mnt/glusterfs
backup-volfile-servers=<volfile_server2>:<volfile_server3>:...:<volfile_serverN>
List of the backup volfile servers to mount the client. If this option is specified while mounting the fuse client, when the first volfile server fails, the servers specified in backup-volfile-servers option are used as volfile servers to mount the client until the mount is successful.

Note

This option was earlier specified as backupvolfile-server which is no longer valid.
log-level
Logs only specified level or higher severity messages in the log-file.
log-file
Logs the messages in the specified file.
transport-type
Specifies the transport type that FUSE client must use to communicate with bricks. If the volume was created with only one transport type, then that becomes the default when no value is specified. In case of tcp,rdma volume, tcp is the default.
dump-fuse
This mount option creates dump of fuse traffic between the glusterfs client (fuse userspace server) and the kernel. The interface to mount a glusterfs volume is the standard mount(8) command from the CLI. This feature enables the same in the mount option.
# mount -t glusterfs -odump-fuse=filename hostname:/volname mount-path
For example,
# mount -t glusterfs -odump-fuse=/dumpfile  10.70.43.18:/arbiter /mnt/arbiter
The above command generates a binary file with the name dumpfile.

Note

The fusedump grows large with time and notably if the client gets a heavy load. So this is not an intended use case to do fusedump during normal usage. It is advised to use this to get a dump from a particular scenario, for diagnostic purposes.
You need to unmount and remount the volume without the fusedump option to stop dumping.
ro
Mounts the file system with read-only permissions.
acl
Enables POSIX Access Control List on mount. See Section 6.5.4, “Checking ACL enablement on a mounted volume” for further information.
background-qlen=n
Enables FUSE to handle n number of requests to be queued before subsequent requests are denied. Default value of n is 64.
enable-ino32
Enables file system to present 32-bit inodes instead of 64-bit inodes.
reader-thread-count=n
Enables FUSE to add n number of reader threads that can give better I/O performance. Default value of n is 1.
lru-limit
This mount command option clears the inodes from the least recently used (lru) list (which keeps non-referenced inodes) after the inode limit has reached.
For example,
# mount -olru-limit=NNNN -t glusterfs hostname:/volname /mnt/mountdir
Where NNNN is a positive integer. The default value of NNNN is 128k (131072) and the recommended value is 20000 and above. If 0 is specified as the lru-limit then it means that no invalidation of inodes from the lru-list.

6.2.3.2. Mounting Volumes Manually

Manually Mount a Red Hat Gluster Storage Volume or Subdirectory

Create a mount point and run the following command as required:
For a Red Hat Gluster Storage Volume
mount -t glusterfs HOSTNAME|IPADDRESS:/VOLNAME /MOUNTDIR
For a Red Hat Gluster Storage Volume's Subdirectory
mount -t glusterfs HOSTNAME|IPADDRESS:/VOLNAME/SUBDIRECTORY /MOUNTDIR

Note

The server specified in the mount command is used to fetch the glusterFS configuration volfile, which describes the volume name. The client then communicates directly with the servers mentioned in the volfile (which may not actually include the server used for mount).
  1. If a mount point has not yet been created for the volume, run the mkdir command to create a mount point.
    # mkdir /mnt/glusterfs
  2. Run the mount -t glusterfs command, using the key in the task summary as a guide.
    1. For a Red Hat Gluster Storage Volume:
      # mount -t glusterfs server1:/test-volume /mnt/glusterfs
    2. For a Red Hat Gluster Storage Volume's Subdirectory
      # mount -t glusterfs server1:/test-volume/sub-dir /mnt/glusterfs

6.2.3.3. Mounting Volumes Automatically

Volumes can be mounted automatically each time the systems starts.
The server specified in the mount command is used to fetch the glusterFS configuration volfile, which describes the volume name. The client then communicates directly with the servers mentioned in the volfile (which may not actually include the server used for mount).
Mounting a Volume Automatically
Mount a Red Hat Gluster Storage Volume automatically at server start.
  1. Open the /etc/fstab file in a text editor.
  2. Append the following configuration to the fstab file:
    For a Red Hat Gluster Storage Volume
    HOSTNAME|IPADDRESS:/VOLNAME /MOUNTDIR glusterfs defaults,_netdev 0 0
    For a Red Hat Gluster Storage Volume's Subdirectory
    HOSTNAME|IPADDRESS:/VOLNAME/SUBDIRECTORY /MOUNTDIR glusterfs defaults,_netdev 0 0
    Using the example server names, the entry contains the following replaced values.
    server1:/test-volume /mnt/glusterfs glusterfs defaults,_netdev 0 0
    OR
    server1:/test-volume/subdir /mnt/glusterfs glusterfs defaults,_netdev 0 0
    If you want to specify the transport type then check the following example:
    server1:/test-volume /mnt/glusterfs glusterfs defaults,_netdev,transport=tcp 0 0
    OR
    server1:/test-volume/sub-dir /mnt/glusterfs glusterfs defaults,_netdev,transport=tcp 0 0

6.2.3.4. Manually Mounting Sub-directories Using Native Client

With Red Hat Gluster Storage 3.x, you can share a single Gluster volume with different clients and they all can mount only a subset of the volume namespace. This feature is similar to the NFS subdirectory mount feature where you can export a subdirectory of an already exported volume. You can also use this feature to restrict full access to any particular volume.
Mounting subdirectories provides the following benefits:
  • Provides namespace isolation so that multiple users can access the storage without risking namespace collision with other users.
  • Prevents the root file system from becoming full in the event of a mount failure.
You can mount a subdirectory using native client by running either of the following commands:
# mount -t glusterfs hostname:/volname/subdir /mount-point
OR
# mount -t glusterfs hostname:/volname -osubdir-mount=subdir /mount-point
For example:
# gluster volume set test-vol auth.allow "/(192.168.10.*|192.168.11.*),/subdir1(192.168.1.*),/subdir2(192.168.8.*)”
In the above example:
  • The auth.allow option allows only the directories specified as the value of the auth.allow option to be mounted.
  • Each group of auth-allow is separated by a comma (,).
  • Each group has a directory separated by parentheses, (), which contains the valid IP addresses.
  • All subdirectories start with /, that is, no relative path to a volume, but everything is an absolute path, taking / as the root directory of the volume.

Note

By default, the authentication is *, where any given subdirectory in a volume can be mounted by all clients.

6.2.3.5. Testing Mounted Volumes

Testing Mounted Red Hat Gluster Storage Volumes

Using the command-line, verify the Red Hat Gluster Storage volumes have been successfully mounted. All three commands can be run in the order listed, or used independently to verify a volume has been successfully mounted.
  1. Run the mount command to check whether the volume was successfully mounted.
    # mount
    server1:/test-volume on /mnt/glusterfs type fuse.glusterfs(rw,allow_other,default_permissions,max_read=131072
    OR
    # mount
    server1:/test-volume/sub-dir on /mnt/glusterfs type fuse.glusterfs(rw,allow_other,default_permissions,max_read=131072
    If transport option is used while mounting a volume, mount status will have the transport type appended to the volume name. For example, for transport=tcp:
    # mount
    server1:/test-volume.tcp on /mnt/glusterfs type fuse.glusterfs(rw,allow_other,default_permissions,max_read=131072
    OR
    # mount
    server1:/test-volume/sub-dir.tcp on /mnt/glusterfs type fuse.glusterfs(rw,allow_other,default_permissions,max_read=131072
  2. Run the df command to display the aggregated storage space from all the bricks in a volume.
    # df -h /mnt/glusterfs
    Filesystem           Size  Used  Avail  Use%  Mounted on
    server1:/test-volume  28T  22T   5.4T   82%   /mnt/glusterfs
  3. Move to the mount directory using the cd command, and list the contents.
    # cd /mnt/glusterfs
    # ls

6.3. NFS

Red Hat Gluster Storage has two NFS server implementations, Gluster NFS and NFS-Ganesha. Gluster NFS supports only NFSv3 protocol, however, NFS-Ganesha supports NFSv3 and NFSv4 protocols.

6.3.1. Support Matrix

The following table contains the feature matrix of the NFS support on Red Hat Gluster Storage 3.1 and later:

Table 6.5. NFS Support Matrix

Features glusterFS NFS (NFSv3) NFS-Ganesha (NFSv3) NFS-Ganesha (NFSv4)
Root-squash Yes Yes Yes
All-squash NoYes Yes
Sub-directory exportsYes Yes Yes
LockingYes Yes Yes
Client based export permissionsYes Yes Yes
NetgroupsYesYesYes
Mount protocolsUDP, TCPUDP, TCPOnly TCP
NFS transport protocolsTCPUDP, TCPTCP
AUTH_UNIXYesYesYes
AUTH_NONEYesYesYes
AUTH_KRBNoYesYes
ACLsYesNoYes
DelegationsN/AN/ANo
High availabilityYes (but with certain limitations. For more information see, "Setting up CTDB for NFS")YesYes
Multi-headYesYesYes
Gluster RDMA volumesYesNot supportedNot supported
DRCNot supportedYesYes
Dynamic exportsNoYesYes
pseudofsN/AN/AYes
NFSv4.1N/AN/AYes

Note

  • Red Hat does not recommend running NFS-Ganesha with any other NFS servers, such as, kernel-NFS and Gluster NFS servers.
  • Only one of NFS-Ganesha, gluster-NFS or kernel-NFS servers can be enabled on a given machine/host as all NFS implementations use the port 2049 and only one can be active at a given time. Hence you must disable kernel-NFS before NFS-Ganesha is started.

6.3.2. Gluster NFS (Deprecated)

Warning

Gluster-NFS is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends the use of Gluster-NFS, and does not support its use in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
Linux, and other operating systems that support the NFSv3 standard can use NFS to access the Red Hat Gluster Storage volumes.

Note

From the Red Hat Gluster Storage 3.2 release onwards, Gluster NFS server will be disabled by default for any new volumes that are created. You can restart Gluster NFS server on the new volumes explicitly if needed. This can be done running the “mount -t nfs” command on the client as below:
# mount -t nfs HOSTNAME:VOLNAME MOUNTPATH
On any one of the server node:
# gluster volume set VOLNAME nfs.disable off
However, existing volumes (using Gluster NFS server) will not be impacted even after upgrade to Red Hat Gluster Storage 3.2 and will have implicit enablement of Gluster NFS server.
Differences in implementation of the NFSv3 standard in operating systems may result in some operational issues. If issues are encountered when using NFSv3, contact Red Hat support to receive more information on Red Hat Gluster Storage client operating system compatibility, and information about known issues affecting NFSv3.
NFS ACL v3 is supported, which allows getfacl and setfacl operations on NFS clients. The following options are provided to configure the Access Control Lists (ACL) in the glusterFS NFS server with the nfs.acl option. For example:
  • To set nfs.acl ON, run the following command:
    # gluster volume set VOLNAME nfs.acl on
  • To set nfs.acl OFF, run the following command:
    # gluster volume set VOLNAME nfs.acl off

Note

ACL is ON by default.
Red Hat Gluster Storage includes Network Lock Manager (NLM) v4. NLM protocol allows NFSv3 clients to lock files across the network. NLM is required to make applications running on top of NFSv3 mount points to use the standard fcntl() (POSIX) and flock() (BSD) lock system calls to synchronize access across clients.
This section describes how to use NFS to mount Red Hat Gluster Storage volumes (both manually and automatically) and how to verify that the volume has been mounted successfully.

Important

On Red Hat Enterprise Linux 7, enable the firewall service in the active zones for runtime and permanent mode using the following commands:
To get a list of active zones, run the following command:
# firewall-cmd --get-active-zones
To allow the firewall service in the active zones, run the following commands:
# firewall-cmd --zone=zone_name --add-service=nfs --add-service=rpc-bind
# firewall-cmd --zone=zone_name --add-service=nfs --add-service=rpc-bind --permanent

6.3.2.1. Setting up CTDB for Gluster NFS (Deprecated)

In a replicated volume environment, the CTDB software (Cluster Trivial Database) has to be configured to provide high availability and lock synchronization for Samba shares. CTDB provides high availability by adding virtual IP addresses (VIPs) and a heartbeat service.
When a node in the trusted storage pool fails, CTDB enables a different node to take over the virtual IP addresses that the failed node was hosting. This ensures the IP addresses for the services provided are always available. However, locks are not migrated as part of failover.

Important

On Red Hat Enterprise Linux 7, enable the CTDB firewall service in the active zones for runtime and permanent mode using the below commands:
To get a list of active zones, run the following command:
# firewall-cmd --get-active-zones
To add ports to the active zones, run the following commands:
# firewall-cmd --zone=zone_name --add-port=4379/tcp
# firewall-cmd --zone=zone_name --add-port=4379/tcp  --permanent

Note

Amazon Elastic Compute Cloud (EC2) does not support VIPs and is hence not compatible with this solution.
6.3.2.1.1. Prerequisites
Follow these steps before configuring CTDB on a Red Hat Gluster Storage Server:
  • If you already have an older version of CTDB (version <= ctdb1.x), then remove CTDB by executing the following command:
    # yum remove ctdb
    After removing the older version, proceed with installing the latest CTDB.

    Note

    Ensure that the system is subscribed to the samba channel to get the latest CTDB packages.
  • Install CTDB on all the nodes that are used as NFS servers to the latest version using the following command:
    # yum install ctdb
  • CTDB uses TCP port 4379 by default. Ensure that this port is accessible between the Red Hat Gluster Storage servers.
6.3.2.1.2. Port and Firewall Information for Gluster NFS
On the GNFS-Client machine, configure firewalld to add ports used by statd, nlm and portmapper services by executing the following commands:
# firewall-cmd --zone=public --add-port=662/tcp --add-port=662/udp \
--add-port=32803/tcp --add-port=32769/udp \
--add-port=111/tcp --add-port=111/udp
# firewall-cmd --zone=public --add-port=662/tcp --add-port=662/udp \
--add-port=32803/tcp --add-port=32769/udp \
--add-port=111/tcp --add-port=111/udp --permanent
Execute the following step on the client and server machines:
  • On Red Hat Enterprise Linux 7, edit /etc/sysconfig/nfs file as mentioned below:
    # sed -i '/STATD_PORT/s/^#//' /etc/sysconfig/nfs

    Note

    This step is not applicable for Red Hat Enterprise Linux 8.
  • Restart the services:
    • For Red Hat Enterprise Linux 6:
      # service nfslock restart
      # service nfs restart

      Important

      Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
    • For Red Hat Enterprise Linux 7:
      # systemctl restart nfs-config
      # systemctl restart rpc-statd
      # systemctl restart nfs-mountd
      # systemctl restart nfslock

      Note

      This step is not applicable for Red Hat Enterprise Linux 8.
6.3.2.1.3. Configuring CTDB on Red Hat Gluster Storage Server
To configure CTDB on Red Hat Gluster Storage server, execute the following steps:
  1. Create a replicate volume. This volume will host only a zero byte lock file, hence choose minimal sized bricks. To create a replicate volume run the following command:
    # gluster volume create volname replica n ipaddress:/brick path.......N times
    where,
    N: The number of nodes that are used as Gluster NFS servers. Each node must host one brick.
    For example:
    # gluster volume create ctdb replica 3 10.16.157.75:/rhgs/brick1/ctdb/b1 10.16.157.78:/rhgs/brick1/ctdb/b2 10.16.157.81:/rhgs/brick1/ctdb/b3
  2. In the following files, replace "all" in the statement META="all" to the newly created volume name
    /var/lib/glusterd/hooks/1/start/post/S29CTDBsetup.sh
    /var/lib/glusterd/hooks/1/stop/pre/S29CTDB-teardown.sh
    For example:
    META="all"
      to
    META="ctdb"
  3. Start the volume.
    # gluster volume start ctdb
    As part of the start process, the S29CTDBsetup.sh script runs on all Red Hat Gluster Storage servers, adds an entry in /etc/fstab for the mount, and mounts the volume at /gluster/lock on all the nodes with Gluster NFS server. It also enables automatic start of CTDB service on reboot.

    Note

    When you stop the special CTDB volume, the S29CTDB-teardown.sh script runs on all Red Hat Gluster Storage servers and removes an entry in /etc/fstab for the mount and unmounts the volume at /gluster/lock.
  4. Verify if the file /etc/sysconfig/ctdb exists on all the nodes that is used as Gluster NFS server. This file contains Red Hat Gluster Storage recommended CTDB configurations.
  5. Create /etc/ctdb/nodes file on all the nodes that is used as Gluster NFS servers and add the IPs of these nodes to the file.
    10.16.157.0
    10.16.157.3
    10.16.157.6
    The IPs listed here are the private IPs of NFS servers.
  6. On all the nodes that are used as Gluster NFS server which require IP failover, create /etc/ctdb/public_addresses file and add the virtual IPs that CTDB should create to this file. Add these IP address in the following format:
    <Virtual IP>/<routing prefix><node interface>
    For example:
    192.168.1.20/24 eth0
    192.168.1.21/24 eth0
  7. Start the CTDB service on all the nodes by executing the following command:
    # service ctdb start

Note

CTDB with gNFS only provides node level high availability and is not capable of detecting NFS service failure. Therefore, CTDB does not provide high availability if the NFS service goes down while the node is still up and running.

6.3.2.2. Using Gluster NFS to Mount Red Hat Gluster Storage Volumes (Deprecated)

You can use either of the following methods to mount Red Hat Gluster Storage volumes:

Note

Currently GlusterFS NFS server only supports version 3 of NFS protocol. As a preferred option, always configure version 3 as the default version in the nfsmount.conf file at /etc/nfsmount.conf by adding the following text in the file:
Defaultvers=3
In case the file is not modified, then ensure to add vers=3 manually in all the mount commands.
# mount nfsserver:export -o vers=3 /MOUNTPOINT
RDMA support in GlusterFS that is mentioned in the previous sections is with respect to communication between bricks and Fuse mount/GFAPI/NFS server. NFS kernel client will still communicate with GlusterFS NFS server over tcp.
In case of volumes which were created with only one type of transport, communication between GlusterFS NFS server and bricks will be over that transport type. In case of tcp,rdma volume it could be changed using the volume set option nfs.transport-type.
After mounting a volume, you can test the mounted volume using the procedure described in .Section 6.3.2.2.4, “Testing Volumes Mounted Using Gluster NFS (Deprecated)”
6.3.2.2.1. Manually Mounting Volumes Using Gluster NFS (Deprecated)
Create a mount point and run the mount command to manually mount a Red Hat Gluster Storage volume using Gluster NFS.
  1. If a mount point has not yet been created for the volume, run the mkdir command to create a mount point.
    # mkdir /mnt/glusterfs
  2. Run the correct mount command for the system.
    For Linux
    # mount -t nfs -o vers=3 server1:/test-volume /mnt/glusterfs
    For Solaris
    # mount -o vers=3 nfs://server1:38467/test-volume /mnt/glusterfs
Manually Mount a Red Hat Gluster Storage Volume using Gluster NFS over TCP
Create a mount point and run the mount command to manually mount a Red Hat Gluster Storage volume using Gluster NFS over TCP.

Note

glusterFS NFS server does not support UDP. If a NFS client such as Solaris client, connects by default using UDP, the following message appears:
requested NFS version or transport protocol is not supported
The option nfs.mount-udp is supported for mounting a volume, by default it is disabled. The following are the limitations:
  • If nfs.mount-udp is enabled, the MOUNT protocol needed for NFSv3 can handle requests from NFS-clients that require MOUNT over UDP. This is useful for at least some versions of Solaris, IBM AIX and HP-UX.
  • Currently, MOUNT over UDP does not have support for mounting subdirectories on a volume. Mounting server:/volume/subdir exports is only functional when MOUNT over TCP is used.
  • MOUNT over UDP does not currently have support for different authentication options that MOUNT over TCP honors. Enabling nfs.mount-udp may give more permissions to NFS clients than intended via various authentication options like nfs.rpc-auth-allow, nfs.rpc-auth-reject and nfs.export-dir.
  1. If a mount point has not yet been created for the volume, run the mkdir command to create a mount point.
    # mkdir /mnt/glusterfs
  2. Run the correct mount command for the system, specifying the TCP protocol option for the system.
    For Linux
    # mount -t nfs -o vers=3,mountproto=tcp server1:/test-volume /mnt/glusterfs
    For Solaris
    # mount -o proto=tcp, nfs://server1:38467/test-volume /mnt/glusterfs
6.3.2.2.2. Automatically Mounting Volumes Using Gluster NFS (Deprecated)
Red Hat Gluster Storage volumes can be mounted automatically using Gluster NFS, each time the system starts.

Note

In addition to the tasks described below, Red Hat Gluster Storage supports Linux, UNIX, and similar operating system's standard method of auto-mounting Gluster NFS mounts.
Update the /etc/auto.master and /etc/auto.misc files, and restart the autofs service. Whenever a user or process attempts to access the directory it will be mounted in the background on-demand.
Mounting a Volume Automatically using NFS
Mount a Red Hat Gluster Storage Volume automatically using NFS at server start.
  1. Open the /etc/fstab file in a text editor.
  2. Append the following configuration to the fstab file.
    HOSTNAME|IPADDRESS:/VOLNAME /MOUNTDIR nfs defaults,_netdev, 0 0
    Using the example server names, the entry contains the following replaced values.
    server1:/test-volume /mnt/glusterfs nfs defaults,_netdev, 0 0
Mounting a Volume Automatically using NFS over TCP
Mount a Red Hat Gluster Storage Volume automatically using NFS over TCP at server start.
  1. Open the /etc/fstab file in a text editor.
  2. Append the following configuration to the fstab file.
    HOSTNAME|IPADDRESS:/VOLNAME /MOUNTDIR nfs defaults,_netdev,mountproto=tcp 0 0
    Using the example server names, the entry contains the following replaced values.
    server1:/test-volume /mnt/glusterfs nfs defaults,_netdev,mountproto=tcp 0 0
6.3.2.2.3. Automatically Mounting Subdirectories Using NFS (Deprecated)
The nfs.export-dir and nfs.export-dirs options provide granular control to restrict or allow specific clients to mount a sub-directory. These clients can be authenticated during sub-directory mount with either an IP, host name or a Classless Inter-Domain Routing (CIDR) range.
nfs.export-dirs
This option is enabled by default. It allows the sub-directories of exported volumes to be mounted by clients without needing to export individual sub-directories. When enabled, all sub-directories of all volumes are exported. When disabled, sub-directories must be exported individually in order to mount them on clients.
To disable this option for all volumes, run the following command:
# gluster volume set VOLNAME nfs.export-dirs off
nfs.export-dir
When nfs.export-dirs is set to on, the nfs.export-dir option allows you to specify one or more sub-directories to export, rather than exporting all subdirectories (nfs.export-dirs on), or only exporting individually exported subdirectories (nfs.export-dirs off).
To export certain subdirectories, run the following command:
# gluster volume set VOLNAME nfs.export-dir subdirectory
The subdirectory path should be the path from the root of the volume. For example, in a volume with six subdirectories, to export the first three subdirectories, the command would be the following:
# gluster volume set myvolume nfs.export-dir /dir1,/dir2,/dir3
Subdirectories can also be exported based on the IP address, hostname, or a Classless Inter-Domain Routing (CIDR) range by adding these details in parentheses after the directory path:
# gluster volume set VOLNAME nfs.export-dir subdirectory(IPADDRESS),subdirectory(HOSTNAME),subdirectory(CIDR)
# gluster volume set myvolume nfs.export-dir /dir1(192.168.10.101),/dir2(storage.example.com),/dir3(192.168.98.0/24)
6.3.2.2.4. Testing Volumes Mounted Using Gluster NFS (Deprecated)
You can confirm that Red Hat Gluster Storage directories are mounting successfully.
To test mounted volumes

Testing Mounted Red Hat Gluster Storage Volumes

Using the command-line, verify the Red Hat Gluster Storage volumes have been successfully mounted. All three commands can be run in the order listed, or used independently to verify a volume has been successfully mounted.
  1. Run the mount command to check whether the volume was successfully mounted.
    # mount
    server1:/test-volume on /mnt/glusterfs type nfs (rw,addr=server1)
  2. Run the df command to display the aggregated storage space from all the bricks in a volume.
    # df -h /mnt/glusterfs
    Filesystem              Size Used Avail Use% Mounted on
    server1:/test-volume    28T  22T  5.4T  82%  /mnt/glusterfs
  3. Move to the mount directory using the cd command, and list the contents.
    # cd /mnt/glusterfs
    # ls

    Note

    The LOCK functionality in NFS protocol is advisory, it is recommended to use locks if the same volume is accessed by multiple clients.

6.3.2.3. Troubleshooting Gluster NFS (Deprecated)

Q: The mount command on the NFS client fails with RPC Error: Program not registered. This error is encountered due to one of the following reasons:
Q: The rpcbind service is not running on the NFS client. This could be due to the following reasons:
Q: The NFS server glusterfsd starts but the initialization fails with nfsrpc- service: portmap registration of program failed error message in the log.
Q: The NFS server start-up fails with the message Port is already in use in the log file.
Q: The mount command fails with NFS server failed error:
Q: The showmount command fails with clnt_create: RPC: Unable to receive error. This error is encountered due to the following reasons:
Q: The application fails with Invalid argument or Value too large for defined data type
Q: After the machine that is running NFS server is restarted the client fails to reclaim the locks held earlier.
Q: The rpc actor failed to complete successfully error is displayed in the nfs.log, even after the volume is mounted successfully.
Q: The mount command fails with No such file or directory.
Q:
The mount command on the NFS client fails with RPC Error: Program not registered. This error is encountered due to one of the following reasons:
  • The NFS server is not running. You can check the status using the following command:
    # gluster volume status
  • The volume is not started. You can check the status using the following command:
    # gluster volume info
  • rpcbind is restarted. To check if rpcbind is running, execute the following command:
    # ps ax| grep rpcbind
A:
  • If the NFS server is not running, then restart the NFS server using the following command:
    # gluster volume start VOLNAME
  • If the volume is not started, then start the volume using the following command:
    # gluster volume start VOLNAME
  • If both rpcbind and NFS server is running then restart the NFS server using the following commands:
    # gluster volume stop VOLNAME
    # gluster volume start VOLNAME
Q:
The rpcbind service is not running on the NFS client. This could be due to the following reasons:
  • The portmap is not running.
  • Another instance of kernel NFS server or glusterNFS server is running.
A:
Start the rpcbind service by running the following command:
# service rpcbind start
Q:
The NFS server glusterfsd starts but the initialization fails with nfsrpc- service: portmap registration of program failed error message in the log.
A:
NFS start-up succeeds but the initialization of the NFS service can still fail preventing clients from accessing the mount points. Such a situation can be confirmed from the following error messages in the log file:
[2010-05-26 23:33:47] E [rpcsvc.c:2598:rpcsvc_program_register_portmap] rpc-service: Could notregister with portmap
[2010-05-26 23:33:47] E [rpcsvc.c:2682:rpcsvc_program_register] rpc-service: portmap registration of program failed
[2010-05-26 23:33:47] E [rpcsvc.c:2695:rpcsvc_program_register] rpc-service: Program registration failed: MOUNT3, Num: 100005, Ver: 3, Port: 38465
[2010-05-26 23:33:47] E [nfs.c:125:nfs_init_versions] nfs: Program init failed
[2010-05-26 23:33:47] C [nfs.c:531:notify] nfs: Failed to initialize protocols
[2010-05-26 23:33:49] E [rpcsvc.c:2614:rpcsvc_program_unregister_portmap] rpc-service: Could not unregister with portmap
[2010-05-26 23:33:49] E [rpcsvc.c:2731:rpcsvc_program_unregister] rpc-service: portmap unregistration of program failed
[2010-05-26 23:33:49] E [rpcsvc.c:2744:rpcsvc_program_unregister] rpc-service: Program unregistration failed: MOUNT3, Num: 100005, Ver: 3, Port: 38465
  1. Start the rpcbind service on the NFS server by running the following command:
    # service rpcbind start
    After starting rpcbind service, glusterFS NFS server needs to be restarted.
  2. Stop another NFS server running on the same machine.
    Such an error is also seen when there is another NFS server running on the same machine but it is not the glusterFS NFS server. On Linux systems, this could be the kernel NFS server. Resolution involves stopping the other NFS server or not running the glusterFS NFS server on the machine. Before stopping the kernel NFS server, ensure that no critical service depends on access to that NFS server's exports.
    On Linux, kernel NFS servers can be stopped by using either of the following commands depending on the distribution in use:
    # service nfs-kernel-server stop
    # service nfs stop
  3. Restart glusterFS NFS server.
Q:
The NFS server start-up fails with the message Port is already in use in the log file.
A:
This error can arise in case there is already a glusterFS NFS server running on the same machine. This situation can be confirmed from the log file, if the following error lines exist:
[2010-05-26 23:40:49] E [rpc-socket.c:126:rpcsvc_socket_listen] rpc-socket: binding socket failed:Address already in use
[2010-05-26 23:40:49] E [rpc-socket.c:129:rpcsvc_socket_listen] rpc-socket: Port is already in use
[2010-05-26 23:40:49] E [rpcsvc.c:2636:rpcsvc_stage_program_register] rpc-service: could not create listening connection
[2010-05-26 23:40:49] E [rpcsvc.c:2675:rpcsvc_program_register] rpc-service: stage registration of program failed
[2010-05-26 23:40:49] E [rpcsvc.c:2695:rpcsvc_program_register] rpc-service: Program registration failed: MOUNT3, Num: 100005, Ver: 3, Port: 38465
[2010-05-26 23:40:49] E [nfs.c:125:nfs_init_versions] nfs: Program init failed
[2010-05-26 23:40:49] C [nfs.c:531:notify] nfs: Failed to initialize protocols
In this release, the glusterFS NFS server does not support running multiple NFS servers on the same machine. To resolve the issue, one of the glusterFS NFS servers must be shutdown.
Q:
The mount command fails with NFS server failed error:
A:
mount: mount to NFS server '10.1.10.11' failed: timed out (retrying).
Review and apply the suggested solutions to correct the issue.
  • Disable name lookup requests from NFS server to a DNS server.
    The NFS server attempts to authenticate NFS clients by performing a reverse DNS lookup to match host names in the volume file with the client IP addresses. There can be a situation where the NFS server either is not able to connect to the DNS server or the DNS server is taking too long to respond to DNS request. These delays can result in delayed replies from the NFS server to the NFS client resulting in the timeout error.
    NFS server provides a work-around that disables DNS requests, instead relying only on the client IP addresses for authentication. The following option can be added for successful mounting in such situations:
    option nfs.addr.namelookup off

    Note

    Remember that disabling the NFS server forces authentication of clients to use only IP addresses. If the authentication rules in the volume file use host names, those authentication rules will fail and client mounting will fail.
  • NFS version used by the NFS client is other than version 3 by default.
    glusterFS NFS server supports version 3 of NFS protocol by default. In recent Linux kernels, the default NFS version has been changed from 3 to 4. It is possible that the client machine is unable to connect to the glusterFS NFS server because it is using version 4 messages which are not understood by glusterFS NFS server. The timeout can be resolved by forcing the NFS client to use version 3. The vers option to mount command is used for this purpose:
    # mount nfsserver:export -o vers=3 /MOUNTPOINT
Q:
The showmount command fails with clnt_create: RPC: Unable to receive error. This error is encountered due to the following reasons:
  • The firewall might have blocked the port.
  • rpcbind might not be running.
A:
Check the firewall settings, and open ports 111 for portmap requests/replies and glusterFS NFS server requests/replies. glusterFS NFS server operates over the following port numbers: 38465, 38466, and 38467.
Q:
The application fails with Invalid argument or Value too large for defined data type
A:
These two errors generally happen for 32-bit NFS clients, or applications that do not support 64-bit inode numbers or large files.
Use the following option from the command-line interface to make glusterFS NFS return 32-bit inode numbers instead:
NFS.enable-ino32 <on | off>
This option is off by default, which permits NFS to return 64-bit inode numbers by default.
Applications that will benefit from this option include those that are:
  • built and run on 32-bit machines, which do not support large files by default,
  • built to 32-bit standards on 64-bit systems.
Applications which can be rebuilt from source are recommended to be rebuilt using the following flag with gcc:
-D_FILE_OFFSET_BITS=64
Q:
After the machine that is running NFS server is restarted the client fails to reclaim the locks held earlier.
A:
The Network Status Monitor (NSM) service daemon (rpc.statd) is started before gluster NFS server. Hence, NSM sends a notification to the client to reclaim the locks. When the clients send the reclaim request, the NFS server does not respond as it is not started yet. Hence the client request fails.
Solution: To resolve the issue, prevent the NSM daemon from starting when the server starts.
Run chkconfig --list nfslock to check if NSM is configured during OS boot.
If any of the entries are on,run chkconfig nfslock off to disable NSM clients during boot, which resolves the issue.
Q:
The rpc actor failed to complete successfully error is displayed in the nfs.log, even after the volume is mounted successfully.
A:
gluster NFS supports only NFS version 3. When nfs-utils mounts a client when the version is not mentioned, it tries to negotiate using version 4 before falling back to version 3. This is the cause of the messages in both the server log and the nfs.log file.
[2013-06-25 00:03:38.160547] W [rpcsvc.c:180:rpcsvc_program_actor] 0-rpc-service: RPC program version not available (req 100003 4)
[2013-06-25 00:03:38.160669] E [rpcsvc.c:448:rpcsvc_check_and_reply_error] 0-rpcsvc: rpc actor failed to complete successfully
To resolve the issue, declare NFS version 3 and the noacl option in the mount command as follows:
# mount -t nfs -o vers=3,noacl server1:/test-volume /mnt/glusterfs
Q:
The mount command fails with No such file or directory.
A:
This problem is encountered as the volume is not present.

6.3.3. NFS Ganesha

NFS-Ganesha is a user space file server for the NFS protocol with support for NFSv3, NFSv4.0, and NFSv4.1.
Red Hat Gluster Storage 3.5 is supported with the community’s V2.7 stable release of NFS-Ganesha on Red Hat Enterprise Linux 7. To understand the various supported features of NFS-ganesha see, Supported Features of NFS-Ganesha.

Note

To install NFS-Ganesha refer, Deploying NFS-Ganesha on Red Hat Gluster Storage in the Red Hat Gluster Storage 3.5 Installation Guide.

6.3.3.1. Supported Features of NFS-Ganesha

The following list briefly describes the supported features of NFS-Ganesha:
Highly Available Active-Active NFS-Ganesha

In a highly available active-active environment, if a NFS-Ganesha server that is connected to a NFS client running a particular application goes down, the application/NFS client is seamlessly connected to another NFS-Ganesha server without any administrative intervention.

Data coherency across the multi-head NFS-Ganesha servers in the cluster is achieved using the Gluster’s Upcall infrastructure. Gluster’s Upcall infrastructure is a generic and extensible framework that sends notifications to the respective glusterfs clients (in this case NFS-Ganesha server) when changes are detected in the back-end file system.
Dynamic Export of Volumes

NFS-Ganesha supports addition and removal of exports dynamically. Dynamic exports is managed by the DBus interface. DBus is a system local IPC mechanism for system management and peer-to-peer application communication.

Exporting Multiple Entries

In NFS-Ganesha, multiple Red Hat Gluster Storage volumes or sub-directories can be exported simultaneously.

Pseudo File System

NFS-Ganesha creates and maintains a NFSv4 pseudo-file system, which provides clients with seamless access to all exported objects on the server.

Access Control List

NFS-Ganesha NFSv4 protocol includes integrated support for Access Control List (ACL)s, which are similar to those used by Windows. These ACLs can be used to identify a trustee and specify the access rights allowed, or denied for that trustee.This feature is disabled by default.

Note

AUDIT and ALARM ACE types are not currently supported.

6.3.3.2. Setting up NFS Ganesha

To set up NFS Ganesha, follow the steps mentioned in the further sections.

Note

You can also set up NFS-Ganesha using gdeploy, that automates the steps mentioned below. For more information, see "Deploying NFS-Ganesha"
6.3.3.2.1. Port and Firewall Information for NFS-Ganesha
You must ensure to open the ports and firewall services:
The following table lists the port details for NFS-Ganesha cluster setup:

Table 6.6. NFS Port Details

Service Port Number Protocol
sshd 22TCP
rpcbind/portmapper 111TCP/UDP
NFS 2049TCP/UDP
mountd 20048TCP/UDP
NLM 32803TCP/UDP
RQuota 875TCP/UDP
statd 662TCP/UDP
pcsd2224TCP
pacemaker_remote3121TCP
corosync5404 and 5405UDP
dlm21064TCP

Note

The port details for the Red Hat Gluster Storage services are listed under section 3. Verifying Port Access.
Defining Service Ports

Ensure the statd service is configured to use the ports mentioned above by executing the following commands on every node in the nfs-ganesha cluster:

  1. On Red Hat Enterprise Linux 7, edit /etc/sysconfig/nfs file as mentioned below:
    # sed -i '/STATD_PORT/s/^#//' /etc/sysconfig/nfs

    Note

    This step is not applicable for Red Hat Enterprise Linux 8.
  2. Restart the statd service:
    For Red Hat Enterprise Linux 7:
    # systemctl restart nfs-config
    # systemctl restart rpc-statd

    Note

    This step is not applicable for Red Hat Enterprise Linux 8.

Note

For the NFS client to use the LOCK functionality, the ports used by LOCKD and STATD daemons has to be configured and opened via firewalld on the client machine:
  1. Edit '/etc/sysconfig/nfs' using following commands:
    # sed -i '/STATD_PORT/s/^#//' /etc/sysconfig/nfs
    # sed -i '/LOCKD_TCPPORT/s/^#//' /etc/sysconfig/nfs
    # sed -i '/LOCKD_UDPPORT/s/^#//' /etc/sysconfig/nfs
  2. Restart the services:
    For Red Hat Enterprise Linux 7:
    # systemctl restart nfs-config
    # systemctl restart rpc-statd
    # systemctl restart nfslock
  3. Open the ports that are configured in the first step using the following command:
    # firewall-cmd --zone=public --add-port=662/tcp --add-port=662/udp \
    --add-port=32803/tcp --add-port=32769/udp \
    --add-port=111/tcp --add-port=111/udp
    # firewall-cmd --zone=public --add-port=662/tcp --add-port=662/udp \
    --add-port=32803/tcp --add-port=32769/udp \
    --add-port=111/tcp --add-port=111/udp --permanent
  4. To ensure NFS client UDP mount does not fail, ensure to open port 2049 by executing the following command:
    # firewall-cmd --zone=zone_name --add-port=2049/udp
    # firewall-cmd --zone=zone_name --add-port=2049/udp --permanent
  • Firewall Settings

    On Red Hat Enterprise Linux 7, enable the firewall services mentioned below.
    1. Get a list of active zones using the following command:
      # firewall-cmd --get-active-zones
    2. Allow the firewall service in the active zones, run the following commands:
      # firewall-cmd --zone=zone_name --add-service=nlm  --add-service=nfs  --add-service=rpc-bind  --add-service=high-availability --add-service=mountd --add-service=rquota
      
      # firewall-cmd --zone=zone_name  --add-service=nlm  --add-service=nfs  --add-service=rpc-bind  --add-service=high-availability --add-service=mountd --add-service=rquota --permanent
      
      # firewall-cmd --zone=zone_name --add-port=662/tcp --add-port=662/udp
      
      # firewall-cmd --zone=zone_name --add-port=662/tcp --add-port=662/udp --permanent
6.3.3.2.2. Prerequisites to run NFS-Ganesha
Ensure that the following prerequisites are taken into consideration before you run NFS-Ganesha in your environment:
  • A Red Hat Gluster Storage volume must be available for export and NFS-Ganesha rpms are installed.
  • Ensure that the fencing agents are configured. For more information on configuring fencing agents, refer to the following documentation:

    Note

    The required minimum number of nodes for a highly available installation/configuration of NFS Ganesha is 3 and a maximum number of supported nodes is 8.
  • Only one of NFS-Ganesha, gluster-NFS or kernel-NFS servers can be enabled on a given machine/host as all NFS implementations use the port 2049 and only one can be active at a given time. Hence you must disable kernel-NFS before NFS-Ganesha is started.
    Disable the kernel-nfs using the following command:
    For Red Hat Enterprise Linux 7

    # systemctl stop nfs-server
    # systemctl disable nfs-server
    To verify if kernel-nfs is disabled, execute the following command:
    # systemctl status nfs-server
    The service should be in stopped state.

    Note

    Gluster NFS will be stopped automatically when NFS-Ganesha is enabled.
    Ensure that none of the volumes have the variable nfs.disable set to 'off'.
  • Ensure to configure the ports as mentioned in Port/Firewall Information for NFS-Ganesha.
  • Edit the ganesha-ha.conf file based on your environment.
  • Reserve virtual IPs on the network for each of the servers configured in the ganesha.conf file. Ensure that these IPs are different than the hosts' static IPs and are not used anywhere else in the trusted storage pool or in the subnet.
  • Ensure that all the nodes in the cluster are DNS resolvable. For example, you can populate the /etc/hosts with the details of all the nodes in the cluster.
  • Make sure the SELinux is in Enforcing mode.
  • Start network service on all machines using the following command:
    For Red Hat Enterprise Linux 7:
    # systemctl start network
  • Create and mount a gluster shared volume by executing the following command:
    # gluster volume set all cluster.enable-shared-storage enable
    volume set: success
    
  • Create a directory named nfs-ganesha under /var/run/gluster/shared_storage

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
  • Copy the ganesha.conf and ganesha-ha.conf files from /etc/ganesha to /var/run/gluster/shared_storage/nfs-ganesha.
  • Enable the glusterfssharedstorage.service service using the following command:
    systemctl enable glusterfssharedstorage.service
  • Enable the nfs-ganesha service using the following command:
    systemctl enable nfs-ganesha
6.3.3.2.3. Configuring the Cluster Services
The HA cluster is maintained using Pacemaker and Corosync. Pacemaker acts a resource manager and Corosync provides the communication layer of the cluster. For more information about Pacemaker/Corosync see the documentation under the Clustering section of the Red Hat Enterprise Linux 7 documentation: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/

Note

It is recommended to use 3 or more nodes to configure NFS Ganesha HA cluster, in order to maintain cluster quorum.
  1. Enable the pacemaker service using the following command:
    For Red Hat Enterprise Linux 7:
    # systemctl enable pacemaker.service
  2. Start the pcsd service using the following command.
    For Red Hat Enterprise Linux 7:
    # systemctl start pcsd

    Note

    • To start pcsd by default after the system is rebooted, execute the following command:
      For Red Hat Enterprise Linux 7:
      # systemctl enable pcsd
  3. Set a password for the user ‘hacluster’ on all the nodes using the following command. Use the same password for all the nodes:
    # echo <password> | passwd --stdin hacluster
  4. Perform cluster authentication between the nodes, where, username is ‘hacluster’, and password is the one you used in the previous step. Ensure to execute the following command on every node:
    For Red Hat Enterprise Linux 7:
    # pcs cluster auth <hostname1> <hostname2> ...
    For Red Hat Enterprise Linux 8:
    # pcs host auth <hostname1> <hostname2> ...

    Note

    The hostname of all the nodes in the Ganesha-HA cluster must be included in the command when executing it on every node.
    For example, in a four node cluster; nfs1, nfs2, nfs3, and nfs4, execute the following command on every node:
    For Red Hat Enterprise Linux 7:
    # pcs cluster auth nfs1 nfs2 nfs3 nfs4
    Username: hacluster
    Password:
    nfs1: Authorized
    nfs2: Authorized
    nfs3: Authorized
    nfs4: Authorized
    For Red Hat Enterprise Linux 8:
    # pcs host auth nfs1 nfs2 nfs3 nfs4
    Username: hacluster
    Password:
    nfs1: Authorized
    nfs2: Authorized
    nfs3: Authorized
    nfs4: Authorized
  5. Key-based SSH authentication without password for the root user has to be enabled on all the HA nodes. Follow these steps:
    1. On one of the nodes (node1) in the cluster, run:
      # ssh-keygen -f /var/lib/glusterd/nfs/secret.pem -t rsa -N ''
    2. Deploy the generated public key from node1 to all the nodes (including node1) by executing the following command for every node:
      # ssh-copy-id -i /var/lib/glusterd/nfs/secret.pem.pub root@<node-ip/hostname>
    3. Copy the ssh keypair from node1 to all the nodes in the Ganesha-HA cluster by executing the following command for every node:
      # scp -i /var/lib/glusterd/nfs/secret.pem /var/lib/glusterd/nfs/secret.* root@<node-ip/hostname>:/var/lib/glusterd/nfs/
  6. As part of cluster setup, port 875 is used to bind to the Rquota service. If this port is already in use, assign a different port to this service by modifying following line in ‘/etc/ganesha/ganesha.conf’ file on all the nodes.
    # Use a non-privileged port for RQuota
    Rquota_Port = 875;
6.3.3.2.4. Creating the ganesha-ha.conf file
The ganesha-ha.conf.sample is created in the following location /etc/ganesha when Red Hat Gluster Storage is installed. Rename the file to ganesha-ha.conf and make the changes based on your environment.
  1. Create a directory named nfs-ganesha under /var/run/gluster/shared_storage

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
  2. Copy the ganesha.conf and ganesha-ha.conf files from /etc/ganesha to /var/run/gluster/shared_storage/nfs-ganesha.
Sample ganesha-ha.conf file:
# Name of the HA cluster created.
# must be unique within the subnet
HA_NAME="ganesha-ha-360"
#
#
# You may use short names or long names; you may not use IP addresses.
# Once you select one, stay with it as it will be mildly unpleasant to clean
# up if you switch later on. Ensure that all names - short and/or long - are in
# DNS or /etc/hosts on all machines in the cluster.
#
# The subset of nodes of the Gluster Trusted Pool that form the ganesha HA
# cluster. Hostname is specified.
HA_CLUSTER_NODES="server1.lab.redhat.com,server2.lab.redhat.com,..."
#
# Virtual IPs for each of the nodes specified above.
VIP_server1="10.0.2.1"
VIP_server2="10.0.2.2"
#VIP_server1_lab_redhat_com="10.0.2.1"
#VIP_server2_lab_redhat_com="10.0.2.2"
....
....

Note

  • Pacemaker handles the creation of the VIP and assigning an interface.
  • Ensure that the VIP is in the same network range.
  • Ensure that the HA_CLUSTER_NODES are specified as hostnames. Using IP addresses will cause clustering to fail.
6.3.3.2.5. Configuring NFS-Ganesha using Gluster CLI
Setting up the HA cluster

To setup the HA cluster, enable NFS-Ganesha by executing the following command:

  1. Enable NFS-Ganesha by executing the following command
    # gluster nfs-ganesha enable

    Note

    Before enabling or disabling NFS-Ganesha, ensure that all the nodes that are part of the NFS-Ganesha cluster are up.
    For example,
    # gluster nfs-ganesha enable
    Enabling NFS-Ganesha requires Gluster-NFS to be disabled across the trusted pool. Do you still want to continue?
     (y/n) y
    This will take a few minutes to complete. Please wait ..
    nfs-ganesha : success

    Note

    After enabling NFS-Ganesha, if rpcinfo -p shows the statd port different from 662, then, restart the statd service:
    For Red Hat Enterprise Linux 7:
    # systemctl restart rpc-statd
    Tearing down the HA cluster

    To tear down the HA cluster, execute the following command:

    # gluster nfs-ganesha disable
    For example,
    # gluster nfs-ganesha disable
    Disabling NFS-Ganesha will tear down entire ganesha cluster across the trusted pool. Do you still want to continue?
    (y/n) y
    This will take a few minutes to complete. Please wait ..
    nfs-ganesha : success
    Verifying the status of the HA cluster

    To verify the status of the HA cluster, execute the following script:

    # /usr/libexec/ganesha/ganesha-ha.sh --status /var/run/gluster/shared_storage/nfs-ganesha

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
    For example:
    # /usr/libexec/ganesha/ganesha-ha.sh --status /var/run/gluster/shared_storage/nfs-ganesha
     Online: [ server1 server2 server3 server4 ]
    server1-cluster_ip-1 server1
    server2-cluster_ip-1 server2
    server3-cluster_ip-1 server3
    server4-cluster_ip-1 server4
    Cluster HA Status: HEALTHY
    

    Note

    • It is recommended to manually restart the ganesha.nfsd service after the node is rebooted, to fail back the VIPs.
    • Disabling NFS Ganesha does not enable Gluster NFS by default. If required, Gluster NFS must be enabled manually.

Note

Ensure to disable the RQUOTA port to avoid the issues described in Section 6.3.3.9, “Troubleshooting NFS Ganesha”
  1. NFS-Ganesha fails to start.
  2. NFS-Ganesha port 875 is unavailable.
To disable RQUOTA port, run the following steps:
  1. The ganesha.conf file is available at /etc/ganesha/ganesha.conf.
  2. Uncomment the line #Enable_RQUOTA = false; to disable RQUOTA.
  3. Restart the nfs-ganesha service on all nodes.
    # systemctl restart nfs-ganesha
6.3.3.2.6. Exporting and Unexporting Volumes through NFS-Ganesha

Note

Start Red Hat Gluster Storage Volume before enabling NFS-Ganesha.
Exporting Volumes through NFS-Ganesha

To export a Red Hat Gluster Storage volume, execute the following command:

# gluster volume set <volname> ganesha.enable on
For example:
# gluster vol set testvol ganesha.enable on
volume set: success
Unexporting Volumes through NFS-Ganesha

To unexport a Red Hat Gluster Storage volume, execute the following command:

# gluster volume set <volname> ganesha.enable off
This command unexports the Red Hat Gluster Storage volume without affecting other exports.
For example:
# gluster vol set testvol ganesha.enable off
volume set: success
6.3.3.2.7. Verifying the NFS-Ganesha Status
To verify the status of the volume set options, follow the guidelines mentioned below:
  • Check if NFS-Ganesha is started by executing the following commands:
    On Red Hat Enterprise Linux-7
    # systemctl status nfs-ganesha
    For example:
    # systemctl  status nfs-ganesha
       nfs-ganesha.service - NFS-Ganesha file server
       Loaded: loaded (/usr/lib/systemd/system/nfs-ganesha.service; disabled)
       Active: active (running) since Tue 2015-07-21 05:08:22 IST; 19h ago
       Docs: http://github.com/nfs-ganesha/nfs-ganesha/wiki
       Main PID: 15440 (ganesha.nfsd)
       CGroup: /system.slice/nfs-ganesha.service
                   └─15440 /usr/bin/ganesha.nfsd -L /var/log/ganesha/ganesha.log -f /etc/ganesha/ganesha.conf -N NIV_EVENT
       Jul 21 05:08:22 server1 systemd[1]: Started NFS-Ganesha file server.]
    
    
  • Check if the volume is exported.
    # showmount -e localhost
    For example:
    # showmount -e localhost
    Export list for localhost:
    /volname (everyone)
  • The logs of ganesha.nfsd daemon are written to /var/log/ganesha/ganesha.log. Check the log file on noticing any unexpected behavior.

6.3.3.3. Accessing NFS-Ganesha Exports

NFS-Ganesha exports can be accessed by mounting them in either NFSv3 or NFSv4 mode. Since this is an active-active HA configuration, the mount operation can be performed from the VIP of any node.
For better large file performance on all workloads that is generated on Red Hat Enterprise Linux 7 clients, it is recommended to set the following tunable before mounting the volume:
  1. Execute the following commands to set the tunable:
    # sysctl -w sunrpc.tcp_slot_table_entries=128
    # echo 128 > /proc/sys/sunrpc/tcp_slot_table_entries
    # echo 128 > /proc/sys/sunrpc/tcp_max_slot_table_entries
  2. To make the tunable persistent on reboot, execute the following commands:
    # echo "options sunrpc tcp_slot_table_entries=128" >> /etc/modprobe.d/sunrpc.conf
    # echo "options sunrpc tcp_max_slot_table_entries=128" >>  /etc/modprobe.d/sunrpc.conf

Note

Ensure that NFS clients and NFS-Ganesha servers in the cluster are DNS resolvable with unique host-names to use file locking through Network Lock Manager (NLM) protocol.
6.3.3.3.1. Mounting exports in NFSv3 Mode
To mount an export in NFSv3 mode, execute the following command:
# mount -t nfs -o vers=3 virtual_ip:/volname /mountpoint
For example:
mount -t nfs -o vers=3 10.70.0.0:/testvol /mnt
6.3.3.3.2. Mounting exports in NFSv4 Mode
To mount an export in NFSv4 mode on RHEL 7 client(s), execute the following command:
# mount -t nfs -o vers=4 virtual_ip:/volname /mountpoint
For example:
# mount -t nfs -o vers=4 10.70.0.0:/testvol /mnt

Important

The default version for RHEL 8 is NFSv4.2
To mount an export in a specific NFS version on RHEL 8 client(s), execute the following command:
# mount -t nfs -o vers=4.0 or 4.1 virtual_ip:/volname /mountpoint
For example:
# mount -t nfs -o vers=4.1 10.70.0.0:/testvol /mnt
6.3.3.3.3. Finding clients of an NFS server using dbus
To display the IP addresses of clients that have mounted the NFS exports, execute the following command:
# dbus-send --type=method_call --print-reply --system --dest=org.ganesha.nfsd /org/ganesha/nfsd/ClientMgr org.ganesha.nfsd.clientmgr.ShowClients

Note

If the NFS export is unmounted or if a client is disconnected from the server, it may take a few minutes for this to be updated in the command output.
6.3.3.3.4.  Finding authorized client list and other information from an NFS server using dbus
To display the authorized client access list and other export options configured from an NFS server, execute the following command:
# dbus-send --type=method_call --print-reply --system --dest=org.ganesha.nfsd /org/ganesha/nfsd/ExportMgr org.ganesha.nfsd.exportmgr.DisplayExport uint16:Export_Id
This command, along with the ACLs, fetches other information like fullpath, pseudopath and tag of the export volume. The fullpath and the pseudopath is used for mounting the export volume.
The dbus DisplayExport command will give clients details of the export volume. The output syntax is as follows:
uint16 export_id
string fullpath
string pseudopath
string tag
array[
  struct {
    string client_type
    int32 CIDR_version
    byte CIDR_address
    byte CIDR_mask
    int32 CIDR_proto
    uint32 anonymous_uid
    uint32 anonymous_gid
    uint32 expire_time_attr
    uint32 options
    uint32 set
    }
    struct {
      .
      .
      .
      }
      .
      .
      .
    ]
In the above output, client_type is the client’s IP address, CIDR_version, CIDR_address, CIDR_mask and CIDR_proto are the CIDR representation details of the client and uint32 anonymous_uid, uint32 anonymous_gid, uint32 expire_time_attr, uint32 options and uint32 set are the Client Permissions.
For example:
#dbus-send --type=method_call --print-reply --system --dest=org.ganesha.nfsd /org/ganesha/nfsd/ExportMgr org.ganesha.nfsd.exportmgr.DisplayExport uint16:2

method return time=1559209192.642525 sender=:1.5491 -> destination=:1.5510 serial=370 reply_serial=2
uint16 2
string "/mani1"
string "/mani1"
string ""
array [
  struct {
    string "10.70.46.107/32"
    int32 0
    byte 0
    byte 255
    int32 1
    uint32 1440
    uint32 72
    uint32 0
    uint32 52441250
    uint32 7340536
    }
  struct {
    string "10.70.47.152/32"
    int32 0
    byte 0
    byte 255
    int32 1
    uint32 1440
    uint32 72
    uint32 0
    uint32 51392994
    uint32 7340536
    }
  ]

6.3.3.4. Modifying the NFS-Ganesha HA Setup

To modify the existing HA cluster and to change the default values of the exports use the ganesha-ha.sh script located at /usr/libexec/ganesha/.
6.3.3.4.1. Adding a Node to the Cluster
Before adding a node to the cluster, ensure that the firewall services are enabled as mentioned in Port Information for NFS-Ganesha and also the prerequisites mentioned in section Pre-requisites to run NFS-Ganesha are met.

Note

Since shared storage and /var/lib/glusterd/nfs/secret.pem SSH key are already generated, those steps should not be repeated.
To add a node to the cluster, execute the following command on any of the nodes in the existing NFS-Ganesha cluster:
# /usr/libexec/ganesha/ganesha-ha.sh --add <HA_CONF_DIR> <HOSTNAME> <NODE-VIP>
where,
HA_CONF_DIR: The directory path containing the ganesha-ha.conf file. By default it is /run/gluster/shared_storage/nfs-ganesha.
HOSTNAME: Hostname of the new node to be added
NODE-VIP: Virtual IP of the new node to be added.
For example:
# /usr/libexec/ganesha/ganesha-ha.sh --add /var/run/gluster/shared_storage/nfs-ganesha server16 10.00.00.01

Note

With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
6.3.3.4.2. Deleting a Node in the Cluster
To delete a node from the cluster, execute the following command on any of the nodes in the existing NFS-Ganesha cluster:
# /usr/libexec/ganesha/ganesha-ha.sh --delete <HA_CONF_DIR> <HOSTNAME>
where,
HA_CONF_DIR: The directory path containing the ganesha-ha.conf file. By default it is located at /run/gluster/shared_storage/nfs-ganesha.
HOSTNAME: Hostname of the node to be deleted
For example:
# /usr/libexec/ganesha/ganesha-ha.sh --delete /var/run/gluster/shared_storage/nfs-ganesha  server16

Note

With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
6.3.3.4.3. Replacing a Node in the Cluster
To replace a node in the existing NFS-Ganesha cluster:
  1. Delete the node from the cluster. Refer Section 6.3.3.4.2, “Deleting a Node in the Cluster”
  2. Note

    It is not required for the new node to have the same name as that of the old node.
  3. Add the node to the cluster. Refer Section 6.3.3.4.1, “Adding a Node to the Cluster”

    Note

6.3.3.5. Modifying the Default Export Configurations

It is recommended to use gluster CLI options to export or unexport volumes through NFS-Ganesha. However, this section provides some information on changing configurable parameters in NFS-Ganesha. Such parameter changes require NFS-Ganesha to be started manually.
For various supported export options see the ganesha-export-config 8 man page.
To modify the default export configurations perform the following steps on any of the nodes in the existing ganesha cluster:
  1. Edit/add the required fields in the corresponding export file located at /run/gluster/shared_storage/nfs-ganesha/exports/.
  2. Execute the following command
    # /usr/libexec/ganesha/ganesha-ha.sh --refresh-config <HA_CONF_DIR> <volname>
where:
  • HA_CONF_DIR: The directory path containing the ganesha-ha.conf file. By default it is located at /run/gluster/shared_storage/nfs-ganesha.
  • volname: The name of the volume whose export configuration has to be changed.
Sample export configuration file:
The following are the default set of parameters required to export any entry. The values given here are the default values used by the CLI options to start or stop NFS-Ganesha.
# cat export.conf

EXPORT{
    Export_Id = 1 ;   # Export ID unique to each export
    Path = "volume_path";  # Path of the volume to be exported. Eg: "/test_volume"

    FSAL {
        name = GLUSTER;
        hostname = "10.xx.xx.xx";  # IP of one of the nodes in the trusted pool
        volume = "volume_name";     # Volume name. Eg: "test_volume"
    }

    Access_type = RW;     # Access permissions
    Squash = No_root_squash; # To enable/disable root squashing
    Disable_ACL = true;     # To enable/disable ACL
    Pseudo = "pseudo_path";     # NFSv4 pseudo path for this export. Eg: "/test_volume_pseudo"
    Protocols = "3”, “4" ;     # NFS protocols supported
    Transports = "UDP”, “TCP" ; # Transport protocols supported
    SecType = "sys";     # Security flavors supported
}
The following sections describe various configurations possible via NFS-Ganesha. Minor changes have to be made to the export.conf file to see the expected behavior.
  • Providing Permissions for Specific Clients
  • Enabling and Disabling NFSv4 ACLs
  • Providing Pseudo Path for NFSv4 Mount
  • Exporting Subdirectories
6.3.3.5.1. Providing Permissions for Specific Clients
The parameter values and permission values given in the EXPORT block applies to any client that mounts the exported volume. To provide specific permissions to specific clients , introduce a client block inside the EXPORT block.
For example, to assign specific permissions for client 10.00.00.01, add the following block in the EXPORT block.
client {
        clients = 10.00.00.01;  # IP of the client.
        access_type = "RO"; # Read-only permissions
        Protocols = "3"; # Allow only NFSv3 protocol.
        anonymous_uid = 1440;
        anonymous_gid = 72;
  }
All the other clients inherit the permissions that are declared outside the client block.
6.3.3.5.2. Enabling and Disabling NFSv4 ACLs
To enable NFSv4 ACLs , edit the following parameter:
Disable_ACL = false;

Note

NFS clients should remount their share after enabling/disabling ACLs on the NFS-Ganesha server.
6.3.3.5.3. Providing Pseudo Path for NFSv4 Mount
To set NFSv4 pseudo path , edit the below parameter:
Pseudo = "pseudo_path"; # NFSv4 pseudo path for this export. Eg: "/test_volume_pseudo"
This path has to be used while mounting the export entry in NFSv4 mode.
6.3.3.5.4. Exporting Subdirectories
You can follow either of the following two methods to export subdir in NFS-ganesha
Method 1: Creating a separate export file. This will export the sub-directory shares without disrupting existing clients connected to other shares
  • Create a separate export file for the sub-directory.
    # cat export.ganesha-dir.conf
            # WARNING : Using Gluster CLI will overwrite manual
            # changes made to this file. To avoid it, edit the
            # file and run ganesha-ha.sh --refresh-config.
            EXPORT{
                  Export_Id = 3;
                  Path = "/ganesha/dir";
                  FSAL {
                       name = GLUSTER;
                       hostname="localhost";
                      volume="ganesha";
                volpath="/dir";
                       }
                  Access_type = RW;
                  Disable_ACL = true;
                  Squash="No_root_squash";
                  Pseudo="/ganesha/dir";
                  Protocols = "3", "4";
                  Transports = "UDP","TCP";
                  SecType = "sys";
                 }
  • Change the Export_ID to any unique unused ID.Edit the PathandPseudoparameters and add the volpath entry to the export file.
  • If a new export file is created for the sub-directory, you must add it's entry in ganesha.conf file.
     %include "/var/run/gluster/shared_storage/nfs-ganesha/exports/export.<share-name>.conf"

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
    For example:
                  %include "/var/run/gluster/shared_storage/nfs-ganesha/exports/export.ganesha.conf" --> Volume entry
                  %include >/var/run/gluster/shared_storage/nfs-ganesha/exports/export.ganesha-dir.conf" --> Subdir entry
  • Execute the following script to export the sub-directory shares without disrupting existing clients connected to other shares :
    # /usr/libexec/ganesha/ganesha-ha.sh --refresh-config <HA_CONF_DIR> <share-name>
    For example:
     /usr/libexec/ganesha/ganesha-ha.sh --refresh-config /run/gluster/shared_storage/nfs-ganesha/ ganesha-dir
Method 2: Editing the volume export file with subdir entries in it. This method will only export the subdir and not the parent volume.
  • Edit the volume export file with subdir entry.
    For Example:
    # cat export.ganesha.conf
                  # WARNING : Using Gluster CLI will overwrite manual
                  # changes made to this file. To avoid it, edit the
                  # file and run ganesha-ha.sh --refresh-config.
                  EXPORT{
                        Export_Id = 4;
                        Path = "/ganesha/dir1";
                        FSAL {
                             name = GLUSTER;
                             hostname="localhost";
                            volume="ganesha";
                            volpath="/dir1";
                             }
                        Access_type = RW;
                        Disable_ACL = true;
                        Squash="No_root_squash";
                        Pseudo="/ganesha/dir1";
                        Protocols = "3", "4";
                        Transports = "UDP","TCP";
                        SecType = "sys";
                       }
  • Change the Export_ID to any unique unused ID.Edit the PathandPseudoparameters and add the volpath entry to the export file.
  • Execute the following script to export the sub-directory shares without disrupting existing clients connected to other shares:
    # /usr/libexec/ganesha/ganesha-ha.sh --refresh-config <HA_CONF_DIR> <share-name>
    For example:
     /usr/libexec/ganesha/ganesha-ha.sh --refresh-config /run/gluster/shared_storage/nfs-ganesha/ ganesha

    Note

    If the same export file contains multiple EXPORT{} entries, then a volume restart or nfs-ganesha service restart is required.
6.3.3.5.4.1. Enabling all_squash option
To enable all_squash, edit the following parameter:
Squash = all_squash ; # To enable/disable root squashing
6.3.3.5.5. Unexporting Subdirectories
Sub-directory in NFS-ganesha can be unexported by the following steps:
  1. Note the export id of the share which you want to unexport from configuration file (/var/run/gluster/shared_storage/nfs-ganesha/exports/file-name.conf)
  2. Deleting the configuration:
    • Delete the configuration file (if there is a seperate configraution file):
      # rm -rf /var/run/gluster/shared_storage/nfs-ganesha/exports/file-name.conf
    • Delete the entry of the conf file from /etc/ganesha/ganesha.conf
      Remove the line:
      %include "/var/run/gluster/shared_storage/nfs-ganesha/export/export.conf
    • Run the below command:
      # dbus-send --print-reply --system --dest=org.ganesha.nfsd /org/ganesha/nfsd/ExportMgr org.ganesha.nfsd.exportmgr.RemoveExport uint16:export_id
      Export_id in above command should be of export entry obtained from step 1.

6.3.3.6. Configuring Kerberized NFS-Ganesha

Note

NTP is no longer supported on Red Hat Enterprise Linux 8.
Execute the following steps on all the machines:
  1. Install the krb5-workstation and the ntpdate (RHEL 7) or the chrony (RHEL 8) packages on all the machines:
    # yum install krb5-workstation
    For Red Hat Enterprise Linux 7:
    # yum install ntpdate
    For Red Hat Enterprise Linux 8:
    # dnf install chrony

    Note

    • The krb5-libs package will be updated as a dependent package.
  2. For RHEL 7, configure the ntpdate based on the valid time server according to the environment:
    # echo <valid_time_server> >> /etc/ntp/step-tickers
    # systemctl enable ntpdate
    # systemctl start ntpdate
    For RHEL 8, configure chrony based on the valid time server accroding to the environment:
      # vi /etc/chrony.conf
      # systemctl enable chrony
      # systemctl start chrony
    For RHEL 7 and RHEL 8 both, perform the following steps:
  3. Ensure that all systems can resolve each other by FQDN in DNS.
  4. Configure the /etc/krb5.conf file and add relevant changes accordingly. For example:
    [logging]
      default = FILE:/var/log/krb5libs.log
      kdc = FILE:/var/log/krb5kdc.log
      admin_server = FILE:/var/log/kadmind.log
    
      [libdefaults]
      dns_lookup_realm = false
      ticket_lifetime = 24h
      renew_lifetime = 7d
      forwardable = true
      rdns = false
      default_realm = EXAMPLE.COM
      default_ccache_name = KEYRING:persistent:%{uid}
    
      [realms]
      EXAMPLE.COM = {
      kdc = kerberos.example.com
        admin_server = kerberos.example.com
      }
    
      [domain_realm]
      .example.com = EXAMPLE.COM
       example.com = EXAMPLE.COM

    Note

    For further details regarding the file configuration, refer to man krb5.conf.
  5. On the NFS-server and client, update the /etc/idmapd.conf file by making the required change. For example:
    Domain = example.com
6.3.3.6.1. Setting up the NFS-Ganesha Server
Execute the following steps to set up the NFS-Ganesha server:

Note

Before setting up the NFS-Ganesha server, make sure to set up the KDC based on the requirements.
  1. Install the following packages:
    # yum install nfs-utils
    # yum install rpcbind
  2. Install the relevant gluster and NFS-Ganesha rpms. For more information see, Red Hat Gluster Storage 3.5 Installation Guide.
  3. Create a Kerberos principle and add it to krb5.keytab on the NFS-Ganesha server
    $ kadmin
    $ kadmin: addprinc -randkey nfs/<host_name>@EXAMPLE.COM
    $ kadmin: ktadd nfs/<host_name>@EXAMPLE.COM
    For example:
    # kadmin
    Authenticating as principal root/admin@EXAMPLE.COM with password.
    Password for root/admin@EXAMPLE.COM:
    
    kadmin:  addprinc -randkey nfs/<host_name>@EXAMPLE.COM
    WARNING: no policy specified for nfs/<host_name>@EXAMPLE.COM; defaulting to no policy
    Principal "nfs/<host_name>@EXAMPLE.COM" created.
    
    
    kadmin:  ktadd nfs/<host_name>@EXAMPLE.COM
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno2, encryption type aes256-cts-hmac-sha1-96 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno 2, encryption type aes128-cts-hmac-sha1-96 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno 2, encryption type des3-cbc-sha1 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno 2, encryption type arcfour-hmac added to keytab FILE:/etc/krb5.keytab.
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno 2, encryption type camellia256-cts-cmac added to keytab FILE:/etc/krb5.keytab.
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno 2, encryption type camellia128-cts-cmac added to keytab FILE:/etc/krb5.keytab.
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno 2, encryption type des-hmac-sha1 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal nfs/<host_name>@EXAMPLE.COM with kvno 2, encryption type des-cbc-md5 added to keytab FILE:/etc/krb5.keytab.
  4. Update /etc/ganesha/ganesha.conf file as mentioned below:
    NFS_KRB5
    {
            PrincipalName = nfs ;
            KeytabPath = /etc/krb5.keytab ;
            Active_krb5 = true ;
    }
  5. Based on the different kerberos security flavours (krb5, krb5i and krb5p) supported by nfs-ganesha, configure the 'SecType' parameter in the volume export file (/var/run/gluster/shared_storage/nfs-ganesha/exports) with appropriate security flavour.

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
  6. Create an unprivileged user and ensure that the users that are created are resolvable to the UIDs through the central user database. For example:
    # useradd guest

    Note

    The username of this user has to be the same as the one on the NFS-client.
6.3.3.6.2. Setting up the NFS Client
Execute the following steps to set up the NFS client:

Note

For a detailed information on setting up NFS-clients for security on Red Hat Enterprise Linux, see Section 8.8.2 NFS Security, in the Red Hat Enterprise Linux 7 Storage Administration Guide.
  1. Install the following packages:
    # yum install nfs-utils
    # yum install rpcbind
  2. Create a kerberos principle and add it to krb5.keytab on the client side. For example:
    # kadmin
    # kadmin: addprinc -randkey host/<host_name>@EXAMPLE.COM
    # kadmin: ktadd host/<host_name>@EXAMPLE.COM
    # kadmin
    Authenticating as principal root/admin@EXAMPLE.COM with password.
    Password for root/admin@EXAMPLE.COM:
    
    kadmin:  addprinc -randkey host/<host_name>@EXAMPLE.COM
    WARNING: no policy specified for host/<host_name>@EXAMPLE.COM; defaulting to no policy
    Principal "host/<host_name>@EXAMPLE.COM" created.
    
    kadmin:  ktadd host/<host_name>@EXAMPLE.COM
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type aes256-cts-hmac-sha1-96 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type aes128-cts-hmac-sha1-96 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type des3-cbc-sha1 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type arcfour-hmac added to keytab FILE:/etc/krb5.keytab.
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type camellia256-cts-cmac added to keytab FILE:/etc/krb5.keytab.
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type camellia128-cts-cmac added to keytab FILE:/etc/krb5.keytab.
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type des-hmac-sha1 added to keytab FILE:/etc/krb5.keytab.
    Entry for principal host/<host_name>@EXAMPLE.COM with kvno 2, encryption type des-cbc-md5 added to keytab FILE:/etc/krb5.keytab.
  3. Check the status of nfs-client.target service and start it, if not already started:
    # systemctl status nfs-client.target
    # systemctl start nfs-client.target
    # systemctl enable nfs-client.target
  4. Create an unprivileged user and ensure that the users that are created are resolvable to the UIDs through the central user database. For example:
    # useradd guest

    Note

    The username of this user has to be the same as the one on the NFS-server.
  5. Mount the volume specifying kerberos security type:
    # mount -t nfs -o sec=krb5 <host_name>:/testvolume /mnt
    As root, all access should be granted.
    For example:
    Creation of a directory on the mount point and all other operations as root should be successful.
    # mkdir <directory name>
  6. Login as a guest user:
    # su - guest
    Without a kerberos ticket, all access to /mnt should be denied. For example:
    # su guest
    # ls
    ls: cannot open directory .: Permission denied
  7. Get the kerberos ticket for the guest and access /mnt:
    # kinit
    Password for guest@EXAMPLE.COM:
    
    # ls
    <directory created>

    Important

    With this ticket, some access must be allowed to /mnt. If there are directories on the NFS-server where "guest" does not have access to, it should work correctly.

6.3.3.7. NFS-Ganesha Service Downtime

In a highly available active-active environment, if a NFS-Ganesha server that is connected to a NFS client running a particular application goes down, the application/NFS client is seamlessly connected to another NFS-Ganesha server without any administrative intervention. However, there is a delay or fail-over time in connecting to another NFS-Ganesha server. This delay can be experienced during fail-back too, that is, when the connection is reset to the original node/server.
The following list describes how the time taken for the NFS server to detect a server reboot or resume is calculated.
  • If the ganesha.nfsd dies (crashes, oomkill, admin kill), the maximum time to detect it and put the ganesha cluster into grace is 20sec, plus whatever time pacemaker needs to effect the fail-over.

    Note

    This time taken to detect if the service is down, can be edited using the following command on all the nodes:
    # pcs resource op remove nfs-mon monitor
    # pcs resource op add nfs-mon monitor interval=<interval_period_value>
  • If the whole node dies (including network failure) then this down time is the total of whatever time pacemaker needs to detect that the node is gone, the time to put the cluster into grace, and the time to effect the fail-over. This is ~20 seconds.
  • So the max-fail-over time is approximately 20-22 seconds, and the average time is typically less. In other words, the time taken for NFS clients to detect server reboot or resume I/O is 20 - 22 seconds.
6.3.3.7.1. Modifying the Fail-over Time
After failover, there is a short period of time during which clients try to reclaim their lost OPEN/LOCK state. Servers block certain file operations during this period, as per the NFS specification. The file operations blocked are as follows:

Table 6.7. 

Protocols File Operations
NFSV3
  • SETATTR
NLM
  • LOCK
  • UNLOCK
  • SHARE
  • UNSHARE
  • CANCEL
  • LOCKT
NFSV4
  • LOCK
  • LOCKT
  • OPEN
  • REMOVE
  • RENAME
  • SETATTR

Note

LOCK, SHARE, and UNSHARE will be blocked only if it is requested with reclaim set to FALSE.
OPEN will be blocked if requested with claim type other than CLAIM_PREVIOUS or CLAIM_DELEGATE_PREV.
The default value for the grace period is 90 seconds. This value can be changed by adding the following lines in the /etc/ganesha/ganesha.conf file.
NFSv4 {
Grace_Period=<grace_period_value_in_sec>;
}
After editing the /etc/ganesha/ganesha.conf file, restart the NFS-Ganesha service using the following command on all the nodes :
On Red Hat Enterprise Linux 7

# systemctl restart nfs-ganesha

6.3.3.8. Tuning Readdir Performance for NFS-Ganesha

The NFS-Ganesha process reads entire content of a directory at an instance. Any parallel operations on that directory are paused until the readdir operation is complete. With Red Hat Gluster Storage 3.5, the Dir_Chunk parameter enables the directory content to be read in chunks at an instance. This parameter is enabled by default. The default value of this parameter is 128. The range for this parameter is 1 to UINT32_MAX. To disable this parameter, set the value to 0

Procedure 6.1. Configuring readdir perform for NFS-Ganesha

  1. Edit the /etc/ganesha/ganesha.conf file.
  2. Locate the CACHEINODE block.
  3. Add the Dir_Chunk parameter inside the block:
    CACHEINODE {
            Entries_HWMark = 125000;
            Chunks_HWMark = 1000;
            Dir_Chunk = 128; # Range: 1 to UINT32_MAX, 0 to disable
    }
  4. Save the ganesha.conf file and restart the NFS-Ganesha service on all nodes:
    # systemctl restart nfs-ganesha

6.3.3.9. Troubleshooting NFS Ganesha

Mandatory checks

Ensure you execute the following commands for all the issues/failures that is encountered:

  • Make sure all the prerequisites are met.
  • Execute the following commands to check the status of the services:
    # service nfs-ganesha status
    # service pcsd status
    # service pacemaker status
    # pcs status
  • Review the followings logs to understand the cause of failure.
    /var/log/ganesha/ganesha.log
    /var/log/ganesha/ganesha-gfapi.log
    /var/log/messages
    /var/log/pcsd.log
    
  • Situation

    NFS-Ganesha fails to start.

    Solution

    Ensure you execute all the mandatory checks to understand the root cause before proceeding with the following steps. Follow the listed steps to fix the issue:

    1. Ensure the kernel and gluster nfs services are inactive.
    2. Ensure that the port 875 is free to connect to the RQUOTA service.
    3. Ensure that the shared storage volume mount exists on the server after node reboot/shutdown. If it does not, then mount the shared storage volume manually using the following command:
      # mount -t glusterfs <local_node's_hostname>:gluster_shared_storage /var/run/gluster/shared_storage

      Note

      With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
    For more information see, section Exporting and Unexporting Volumes through NFS-Ganesha.
  • Situation

    NFS-Ganesha port 875 is unavailable.

    Solution

    Ensure you execute all the mandatory checks to understand the root cause before proceeding with the following steps. Follow the listed steps to fix the issue:

    1. Run the following command to extract the PID of the process using port 875:
      netstat -anlp | grep 875
    2. Determine if the process using port 875 is an important system or user process.
    3. Perform one of the following depending upon the importance of the process:
      • If the process using port 875 is an important system or user process:
        1. Assign a different port to this service by modifying following line in ‘/etc/ganesha/ganesha.conf’ file on all the nodes:
          # Use a non-privileged port for RQuota
          Rquota_Port = port_number;
        2. Run the following commands after modifying the port number:
          # semanage port -a -t mountd_port_t -p tcp port_number
          # semanage port -a -t mountd_port_t -p udp port_number
        3. Run the following command to restart NFS-Ganesha:
          systemctl restart nfs-ganesha
      • If the process using port 875 is not an important system or user process:
        1. Run the following command to kill the process using port 875:
          # kill pid;
          Use the process ID extracted from the previous step.
        2. Run the following command to ensure that the process is killed and port 875 is free to use:
          # ps aux | grep pid;
        3. Run the following command to restart NFS-Ganesha:
          systemctl restart nfs-ganesha
        4. If required, restart the killed process.
  • Situation

    NFS-Ganesha Cluster setup fails.

    Solution

    Ensure you execute all the mandatory checks to understand the root cause before proceeding with the following steps.

    1. Ensure the kernel and gluster nfs services are inactive.
    2. Ensure that pcs cluster auth command is executed on all the nodes with same password for the user hacluster
    3. Ensure that shared volume storage is mounted on all the nodes.
    4. Ensure that the name of the HA Cluster does not exceed 15 characters.
    5. Ensure UDP multicast packets are pingable using OMPING.
    6. Ensure that Virtual IPs are not assigned to any NIC.
  • Situation

    NFS-Ganesha has started and fails to export a volume.

    Solution

    Ensure you execute all the mandatory checks to understand the root cause before proceeding with the following steps. Follow the listed steps to fix the issue:

    1. Ensure that volume is in Started state using the following command:
      # gluster volume status <volname>
      
    2. Execute the following commands to check the status of the services:
      # service nfs-ganesha status
      # showmount -e localhost
    3. Review the followings logs to understand the cause of failure.
      /var/log/ganesha/ganesha.log
      /var/log/ganesha/ganesha-gfapi.log
      /var/log/messages
    4. Ensure that dbus service is running using the following command
      # service messagebus status
    5. If the volume is not in a started state, run the following command to start the volume.
      # gluster volume start <volname>
      If the volume is not exported as part of volume start, run the following command to re-export the volume:
      # /usr/libexec/ganesha/dbus-send.sh /var/run/gluster/shared_storage on <volname>

      Note

      With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
  • Situation

    Adding a new node to the HA cluster fails.

    Solution

    Ensure you execute all the mandatory checks to understand the root cause before proceeding with the following steps. Follow the listed steps to fix the issue:

    1. Ensure to run the following command from one of the nodes that is already part of the cluster:
      # ganesha-ha.sh --add <HA_CONF_DIR>  <NODE-HOSTNAME>  <NODE-VIP>
    2. Ensure that gluster_shared_storage volume is mounted on the node that needs to be added.
    3. Make sure that all the nodes of the cluster is DNS resolvable from the node that needs to be added.
    4. Execute the following command for each of the hosts in the HA cluster on the node that needs to be added:
      For Red Hat Enterprize Linux 7:
      # pcs cluster auth <hostname>
      For Red Hat Enterprize Linux 8:
      # pcs host auth <hostname>
  • Situation

    Cleanup required when nfs-ganesha HA cluster setup fails.

    Solution

    To restore back the machines to the original state, execute the following commands on each node forming the cluster:

    # /usr/libexec/ganesha/ganesha-ha.sh --teardown /var/run/gluster/shared_storage/nfs-ganesha
    # /usr/libexec/ganesha/ganesha-ha.sh --cleanup /var/run/gluster/shared_storage/nfs-ganesha
    # systemctl stop nfs-ganesha

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
  • Situation

    Permission issues.

    Solution

    By default, the root squash option is disabled when you start NFS-Ganesha using the CLI. In case, you encounter any permission issues, check the unix permissions of the exported entry.

6.4. SMB

You can access Red Hat Gluster Storage volumes using the Server Message Block (SMB) protocol by exporting directories in Red Hat Gluster Storage volumes as SMB shares on the server.
This section describes how to enable SMB shares, how to mount SMB shares manually and automatically on Microsoft Windows and macOS based clients, and how to verify that the share has been mounted successfully.

Warning

When performance translators are enabled, data inconsistency is observed when multiple clients access the same data. To avoid data inconsistency, you can either disable the performance translators or avoid such workloads.
Follow the process outlined below. The details of this overview are provided in the rest of this section.

6.4.1. Requirements for using SMB with Red Hat Gluster Storage

  • Samba is required to provide support and interoperability for the SMB protocol on Red Hat Gluster Storage. Additionally, CTDB is required when you want to share replicated volumes using SMB. See Subscribing to the Red Hat Gluster Storage server channels in the Red Hat Gluster Storage 3.5 Installation Guide for information on subscribing to the correct channels for SMB support.
  • Enable the Samba firewall service in the active zones for runtime and permanent mode. The following commands are for systems based on Red Hat Enterprise Linux 7.
    To get a list of active zones, run the following command:
    # firewall-cmd --get-active-zones
    To allow the firewall services in the active zones, run the following commands
    # firewall-cmd --zone=zone_name --add-service=samba
    # firewall-cmd --zone=zone_name --add-service=samba  --permanent

6.4.2. Setting up CTDB for Samba

If you want to share volumes that use replication using SMB, you need to configure CTDB (Cluster Trivial Database) to provide high availability and lock synchronization.
CTDB provides high availability by adding virtual IP addresses (VIPs) and a heartbeat service. When a node in the trusted storage pool fails, CTDB enables a different node to take over the virtual IP addresses that the failed node was hosting. This ensures the IP addresses for the services provided are always available.

Important

Amazon Elastic Compute Cloud (EC2) does not support VIPs and is hence not compatible with this solution.

Prerequisites

  • If you already have an older version of CTDB (version <= ctdb1.x), then remove CTDB by executing the following command:
    # yum remove ctdb
    After removing the older version, proceed with installing the latest CTDB.

    Note

    Ensure that the system is subscribed to the samba channel to get the latest CTDB packages.
  • Install CTDB on all the nodes that are used as Samba servers to the latest version using the following command:
    # yum install ctdb
  • In a CTDB based high availability environment of Samba , the locks will not be migrated on failover.
  • Enable the CTDB firewall service in the active zones for runtime and permanent mode. The following commands are for systems based on Red Hat Enterprise Linux 7.
    To get a list of active zones, run the following command:
    # firewall-cmd --get-active-zones
    To add ports to the active zones, run the following commands:
    # firewall-cmd --zone=zone_name --add-port=4379/tcp
    # firewall-cmd --zone=zone_name --add-port=4379/tcp  --permanent

Best Practices

  • CTDB requires a different broadcast domain from the Gluster internal network. The network used by the Windows clients to access the Gluster volumes exported by Samba, must be different from the internal Gluster network. Failing to do so can lead to an excessive time when there is a failover of CTDB between the nodes, and a degraded performance accessing the shares in Windows.
    For example an incorrect setup where CTDB is running in Network 192.168.10.X:
    Status of volume: ctdb
    Gluster process                             TCP Port  RDMA Port  Online  Pid
    Brick node1:/rhgs/ctdb/b1                   49157     0          Y       30439
    Brick node2:/rhgs/ctdb/b1                   49157     0          Y       3827
    Brick node3:/rhgs/ctdb/b1                   49157     0          Y       89421
    Self-heal Daemon on localhost                N/A      N/A        Y       183026
    Self-heal Daemon on sesdel0207               N/A      N/A        Y       44245
    Self-heal Daemon on segotl4158               N/A      N/A        Y       110627
    
    cat ctdb_listnodes
    
    192.168.10.1
    192.168.10.2
    
    cat ctdb_ip
    Public IPs on node 0
    192.168.10.3 0
    

    Note

    The host names, node1, node2, and node3 are used to setup the bricks and resolve the IPs in the same network 192.168.10.X. The Windows clients are accessing the shares using the internal Gluster network and this should not be the case.
  • Additionally, the CTDB network and the Gluster internal network must run in separate physical interfaces. Red Hat recommends 10GbE interfaces for better performance.
  • It is recommended to use the same network bandwidth for Gluster and CTDB networks. Using different network speeds can lead to performance bottlenecks.The same amount of network traffic is expected in both internal and external networks.

Configuring CTDB on Red Hat Gluster Storage Server

  1. Create a new replicated volume to house the CTDB lock file. The lock file has a size of zero bytes, so use small bricks.
    To create a replicated volume run the following command, replacing N with the number of nodes to replicate across:
    # gluster volume create volname replica N ip_address_1:brick_path ... ip_address_N:brick_path
    For example:
    # gluster volume create ctdb replica 3 10.16.157.75:/rhgs/brick1/ctdb/b1 10.16.157.78:/rhgs/brick1/ctdb/b2 10.16.157.81:/rhgs/brick1/ctdb/b3
  2. In the following files, replace all in the statement META="all" with the newly created volume name, for example, META="ctdb".
    /var/lib/glusterd/hooks/1/start/post/S29CTDBsetup.sh
    /var/lib/glusterd/hooks/1/stop/pre/S29CTDB-teardown.sh
  3. In the /etc/samba/smb.conf file, add the following line in the global section on all the nodes:
    clustering=yes
  4. Start the volume.
    # gluster volume start ctdb
    The S29CTDBsetup.sh script runs on all Red Hat Gluster Storage servers, adds an entry in /etc/fstab for the mount, and mounts the volume at /gluster/lock on all the nodes with Samba server. It also enables automatic start of CTDB service on reboot.

    Note

    When you stop the special CTDB volume, the S29CTDB-teardown.sh script runs on all Red Hat Gluster Storage servers and removes an entry in /etc/fstab for the mount and unmounts the volume at /gluster/lock.
  5. Verify that the /etc/ctdb directory exists on all nodes that are used as a Samba server. This file contains CTDB configuration details recommended for Red Hat Gluster Storage.
  6. Create the /etc/ctdb/nodes file on all the nodes that are used as Samba servers and add the IP addresses of these nodes to the file.
    10.16.157.0
    10.16.157.3
    10.16.157.6
    The IP addresses listed here are the private IP addresses of Samba servers.
  7. On nodes that are used as Samba servers and require IP failover, create the /etc/ctdb/public_addresses file. Add any virtual IP addresses that CTDB should create to the file in the following format:
    VIP/routing_prefix network_interface
    For example:
    192.168.1.20/24 eth0
    192.168.1.21/24 eth0
  8. Start the CTDB service on all the nodes.
    On RHEL 7 and RHEL 8, run
    # systemctl start ctdb
    On RHEL 6, run
    # service ctdb start

6.4.3. Sharing Volumes over SMB

After you follow this process, any gluster volumes configured on servers that run Samba are exported automatically on volume start.
See the below example for a default volume share section added to /etc/samba/smb.conf:
[gluster-VOLNAME]
comment = For samba share of volume VOLNAME
vfs objects = glusterfs
glusterfs:volume = VOLNAME
glusterfs:logfile = /var/log/samba/VOLNAME.log
glusterfs:loglevel = 7
path = /
read only = no
guest ok = yes
The configuration options are described in the following table:

Table 6.8. Configuration Options

Configuration Options Required? Default Value Description
Path Yes n/a It represents the path that is relative to the root of the gluster volume that is being shared. Hence / represents the root of the gluster volume. Exporting a subdirectory of a volume is supported and /subdir in path exports only that subdirectory of the volume.
glusterfs:volume Yes n/a The volume name that is shared.
glusterfs:logfile No NULL Path to the log file that will be used by the gluster modules that are loaded by the vfs plugin. Standard Samba variable substitutions as mentioned in smb.conf are supported.
glusterfs:loglevel No 7 This option is equivalent to the client-log-level option of gluster. 7 is the default value and corresponds to the INFO level.
glusterfs:volfile_server No localhost The gluster server to be contacted to fetch the volfile for the volume. It takes the value, which is a list of white space separated elements, where each element is unix+/path/to/socket/file or [tcp+]IP|hostname|\[IPv6\][:port]
The procedure to share volumes over samba differs depending on the Samba version you would choose.

If you are using an older version of Samba:

  1. Enable SMB specific caching:
    # gluster volume set VOLNAME performance.cache-samba-metadata on
    You can also enable generic metadata caching to improve performance. See Section 19.7, “Directory Operations” for details.
  2. Restart the glusterd service on each Red Hat Gluster Storage node.
  3. Verify proper lock and I/O coherence:
    # gluster volume set VOLNAME storage.batch-fsync-delay-usec 0

Note

For RHEL based Red Hat Gluster Storage upgrading to 3.5 batch update 4 with Samba, the write-behind translator has to manually disabled for all existing samba volumes.
# gluster volume set <volname> performance.write-behind off

If you are using Samba-4.8.5-104 or later:

  1. To export gluster volume as SMB share via Samba, one of the following volume options, user.cifs or user.smb is required.
    To enable user.cifs volume option, run:
    # gluster volume set VOLNAME user.cifs enable
    And to enable user.smb, run:
    # gluster volume set VOLNAME user.smb enable
    Red Hat Gluster Storage 3.4 introduces a group command samba for configuring the necessary volume options for Samba-CTDB setup.
  2. Execute the following command to configure the volume options for the Samba-CTDB:
    # gluster volume set VOLNAME group samba
    This command will enable the following option for Samba-CTDB setup:
    • performance.readdir-ahead: on
    • performance.parallel-readdir: on
    • performance.nl-cache-timeout: 600
    • performance.nl-cache: on
    • performance.cache-samba-metadata: on
    • network.inode-lru-limit: 200000
    • performance.md-cache-timeout: 600
    • performance.cache-invalidation: on
    • features.cache-invalidation-timeout: 600
    • features.cache-invalidation: on
    • performance.stat-prefetch: on

If you are using Samba-4.9.8-109 or later:

Below mentioned steps are strictly optional and are to be followed in environments where large number of clients are connecting to volumes and/or more volumes are being used.
Red Hat Gluster Storage 3.5 introduces an optional method for configuring volume shares out of corresponding FUSE mounted paths. Following steps need to be performed on every node in the cluster.
  1. Have a local mount using native Gluster protocol Fuse on every Gluster node that shares the Gluster volume via Samba. Mount GlusterFS volume via FUSE and record the FUSE mountpoint for further steps:
    Add an entry in /etc/fstab:
    localhost:/myvol /mylocal glusterfs defaults,_netdev,acl 0 0
    For example:
    localhost:/myvol 4117504 1818292 2299212 45% /mylocal
    Where gluster volume is myvol that will be mounted on /mylocal
  2. Edit the samba share configuration file located at /etc/samba/smb.conf
    [gluster-VOLNAME]
    comment = For samba share of volume VOLNAME
    vfs objects = glusterfs
    glusterfs:volume = VOLNAME
    glusterfs:logfile = /var/log/samba/VOLNAME.log
    glusterfs:loglevel = 7
    path = /
    read only = no
    guest ok = yes
    • Edit the vfs objects parameter value to glusterfs_fuse
      vfs objects = glusterfs_fuse
    • Edit the path parameter value to the FUSE mountpoint recorded previously. For example:
      path = /MOUNTDIR
  3. With SELinux in Enforcing mode, turn on the SELinux boolean samba_share_fusefs:
    # setsebool -P samba_share_fusefs on

Note

  • New volumes being created will be automatically configured with the use of default vfs objects parameter.
  • Modifications to samba share configuration file are retained over restart of volumes until these volumes are deleted using Gluster CLI.
  • The Samba hook scripts invoked as part of Gluster CLI operations on a volume VOLNAME will only operate on a Samba share named [gluster-VOLNAME]. In other words, hook scripts will never delete or change the samba share configuration file for a samba share called [VOLNAME].

Then, for all Samba versions:

  1. Verify that the volume can be accessed from the SMB/CIFS share:
    # smbclient -L <hostname> -U%
    For example:
    # smbclient -L rhs-vm1 -U%
    Domain=[MYGROUP] OS=[Unix] Server=[Samba 4.1.17]
    
         Sharename       Type      Comment
         ---------       ----      -------
         IPC$            IPC       IPC Service (Samba Server Version 4.1.17)
         gluster-vol1    Disk      For samba share of volume vol1
    Domain=[MYGROUP] OS=[Unix] Server=[Samba 4.1.17]
    
         Server               Comment
         ---------            -------
    
         Workgroup            Master
         ---------            -------
  2. Verify that the SMB/CIFS share can be accessed by the user, run the following command:
    # smbclient //<hostname>/gluster-<volname> -U <username>%<password>
    For example:
    # smbclient //10.0.0.1/gluster-vol1 -U root%redhat
    Domain=[MYGROUP] OS=[Unix] Server=[Samba 4.1.17]
    smb: \> mkdir test
    smb: \> cd test\
    smb: \test\> pwd
    Current directory is \\10.0.0.1\gluster-vol1\test\
    smb: \test\>

6.4.4. Configuring User Access to Shared Volumes

6.4.4.1. Configuring the Apple Create Context for macOS users

  1. Add the following lines to the [global] section of the smb.conf file. Note that the indentation level shown is required.
                fruit:aapl = yes
                ea support = yes
  2. Load the vfs_fruit module and its dependencies by adding the following line to your volume's export configuration block in the smb.conf file.
    vfs objects = fruit streams_xattr glusterfs
    For example:
    [gluster-volname]
    comment = For samba share of volume smbshare
    vfs objects = fruit streams_xattr glusterfs
    glusterfs:volume = volname
    glusterfs:logfile = /var/log/samba/glusterfs-volname-fruit.%M.log
    glusterfs:loglevel = 7
    path = /
    read only = no
    guest ok = yes
    
    fruit:encoding = native

6.4.4.2. Configuring read/write access for a non-privileged user

  1. Add the user on all the Samba servers based on your configuration:
    # adduser username
  2. Add the user to the list of Samba users on all Samba servers and assign password by executing the following command:
    # smbpasswd -a username
  3. From any other Samba server, mount the volume using the FUSE protocol.
    # mount -t glusterfs -o acl ip-address:/volname /mountpoint
    For example:
    # mount -t glusterfs -o acl rhs-a:/repvol /mnt
  4. Use the setfacl command to provide the required permissions for directory access to the user.
    # setfacl -m user:username:rwx mountpoint
    For example:
    # setfacl -m user:cifsuser:rwx /mnt

6.4.5. Mounting Volumes using SMB

6.4.5.1. Manually mounting volumes exported with SMB on Red Hat Enterprise Linux

  1. Install the cifs-utils package on the client.
    # yum install cifs-utils
  2. Run mount -t cifs to mount the exported SMB share, using the syntax example as guidance.
    # mount -t cifs -o user=username,pass=password  //hostname/gluster-volname /mountpoint
    The sec=ntlmssp parameter is also required when mounting a volume on Red Hat Enterprise Linux 6.
    # mount -t cifs -o user=username,pass=password,sec=ntlmssp //hostname/gluster-volname /mountpoint
    For example:
    # mount -t cifs -o user=cifsuser,pass=redhat,sec=ntlmssp //server1/gluster-repvol /cifs

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  3. Run # smbstatus -S on the server to display the status of the volume:
    Service        pid     machine             Connected at
    -------------------------------------------------------------------
    gluster-VOLNAME 11967   __ffff_192.168.1.60  Mon Aug  6 02:23:25 2012

6.4.5.2. Manually mounting volumes exported with SMB on Microsoft Windows

6.4.5.2.1. Using Microsoft Windows Explorer to manually mount a volume
  1. In Windows Explorer, click ToolsMap Network Drive…. to open the Map Network Drive screen.
  2. Choose the drive letter using the Drive drop-down list.
  3. In the Folder text box, specify the path of the server and the shared resource in the following format: \\SERVER_NAME\VOLNAME.
  4. Click Finish to complete the process, and display the network drive in Windows Explorer.
  5. Navigate to the network drive to verify it has mounted correctly.
6.4.5.2.2. Using Microsoft Windows command line interface to manually mount a volume
  1. Click StartRun, and then type cmd.
  2. Enter net use z: \\SERVER_NAME\VOLNAME, where z: is the drive letter to assign to the shared volume.
    For example, net use y: \\server1\test-volume
  3. Navigate to the network drive to verify it has mounted correctly.

6.4.5.3. Manually mounting volumes exported with SMB on macOS

Prerequisites

  • Ensure that your Samba configuration allows the use the SMB Apple Create Context.
  • Ensure that the username you're using is on the list of allowed users for the volume.

Manual mounting process

  1. In the Finder, click Go > Connect to Server.
  2. In the Server Address field, type the IP address or hostname of a Red Hat Gluster Storage server that hosts the volume you want to mount.
  3. Click Connect.
  4. When prompted, select Registered User to connect to the volume using a valid username and password.
    If required, enter your user name and password, then select the server volumes or shared folders that you want to mount.
    To make it easier to connect to the computer in the future, select Remember this password in my keychain to add your user name and password for the computer to your keychain.
For further information about mounting volumes on macOS, see the Apple Support documentation: https://support.apple.com/en-in/guide/mac-help/mchlp1140/mac.

6.4.5.4. Configuring automatic mounting for volumes exported with SMB on Red Hat Enterprise Linux

  1. Open the /etc/fstab file in a text editor and add a line containing the following details:
    \\HOSTNAME|IPADDRESS\SHARE_NAME MOUNTDIR cifs OPTIONS DUMP FSCK
    In the OPTIONS column, ensure that you specify the credentials option, with a value of the path to the file that contains the username and/or password.
    Using the example server names, the entry contains the following replaced values.
    \\server1\test-volume /mnt/glusterfs cifs credentials=/etc/samba/passwd,_netdev 0 0
    The sec=ntlmssp parameter is also required when mounting a volume on Red Hat Enterprise Linux 6, for example:
    \\server1\test-volume /mnt/glusterfs cifs credentials=/etc/samba/passwd,_netdev,sec=ntlmssp 0 0
    See the mount.cifs man page for more information about these options.

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  2. Run # smbstatus -S on the client to display the status of the volume:
    Service        pid     machine             Connected at
    -------------------------------------------------------------------
    gluster-VOLNAME 11967   __ffff_192.168.1.60  Mon Aug  6 02:23:25 2012

6.4.5.5. Configuring automatic mounting for volumes exported with SMB on Microsoft Windows

  1. In Windows Explorer, click ToolsMap Network Drive…. to open the Map Network Drive screen.
  2. Choose the drive letter using the Drive drop-down list.
  3. In the Folder text box, specify the path of the server and the shared resource in the following format: \\SERVER_NAME\VOLNAME.
  4. Click the Reconnect at logon check box.
  5. Click Finish to complete the process, and display the network drive in Windows Explorer.
  6. If the Windows Security screen pops up, enter the username and password and click OK.
  7. Navigate to the network drive to verify it has mounted correctly.

6.4.5.6. Configuring automatic mounting for volumes exported with SMB on macOS

  1. Manually mount the volume using the process outlined in Section 6.4.5.3, “Manually mounting volumes exported with SMB on macOS”.
  2. In the Finder, click System Preferences > Users & Groups > Username > Login Items.
  3. Drag and drop the mounted volume into the login items list.
    Check Hide if you want to prevent the drive's window from opening every time you boot or log in.
For further information about mounting volumes on macOS, see the Apple Support documentation: https://support.apple.com/en-in/guide/mac-help/mchlp1140/mac.

6.4.6. Starting and Verifying your Configuration

Perform the following to start and verify your configuration:

Verify the Configuration

Verify the virtual IP (VIP) addresses of a shut down server are carried over to another server in the replicated volume.
  1. Verify that CTDB is running using the following commands:
    # ctdb status
    # ctdb ip
    # ctdb ping -n all
  2. Mount a Red Hat Gluster Storage volume using any one of the VIPs.
  3. Run # ctdb ip to locate the physical server serving the VIP.
  4. Shut down the CTDB VIP server to verify successful configuration.
    When the Red Hat Gluster Storage server serving the VIP is shut down there will be a pause for a few seconds, then I/O will resume.

6.4.7. Disabling SMB Shares

To stop automatic sharing on all nodes for all volumes execute the following steps:

  1. On all Red Hat Gluster Storage Servers, with elevated privileges, navigate to /var/lib/glusterd/hooks/1/start/post
  2. Rename the S30samba-start.sh to K30samba-start.sh.
    For more information about these scripts, see Section 13.2, “Prepackaged Scripts”.
To stop automatic sharing on all nodes for one particular volume:

  1. Run the following command to disable automatic SMB sharing per-volume:
    # gluster volume set <VOLNAME> user.smb disable

6.4.8. Accessing Snapshots in Windows

A snapshot is a read-only point-in-time copy of the volume. Windows has an inbuilt mechanism to browse snapshots via Volume Shadow-copy Service (also known as VSS). Using this feature users can access the previous versions of any file or folder with minimal steps.

Note

Shadow Copy (also known as Volume Shadow-copy Service, or VSS) is a technology included in Microsoft Windows that allows taking snapshots of computer files or volumes, apart from viewing snapshots. Currently we only support viewing of snapshots. Creation of snapshots with this interface is NOT supported.

6.4.8.1. Configuring Shadow Copy

To configure shadow copy, the following configurations must be modified/edited in the smb.conf file. The smb.conf file is located at etc/samba/smb.conf.

Note

Ensure, shadow_copy2 module is enabled in smb.conf. To enable add the following parameter to the vfs objects option.
For example:
vfs objects = shadow_copy2 glusterfs

Table 6.9. Configuration Options

Configuration Options Required? Default Value Description
shadow:snapdir Yes n/a Path to the directory where snapshots are kept. The snapdir name should be .snaps.
shadow:basedir Yes n/aPath to the base directory that snapshots are from. The basedir value should be /.
shadow:sort Optional unsorted The supported values are asc/desc. By this parameter one can specify that the shadow copy directories should be sorted before they are sent to the client. This can be beneficial as unix filesystems are usually not listed alphabetically sorted. If enabled, it is specified in descending order.
shadow:localtime Optional UTC This is an optional parameter that indicates whether the snapshot names are in UTC/GMT or in local time.
shadow:format Yes n/a This parameter specifies the format specification for the naming of snapshots. The format must be compatible with the conversion specifications recognized by str[fp]time. The default value is _GMT-%Y.%m.%d-%H.%M.%S.
shadow:fixinodesOptionalNo If you enable shadow:fixinodes then this module will modify the apparent inode number of files in the snapshot directories using a hash of the files path. This is needed for snapshot systems where the snapshots have the same device:inode number as the original files (such as happens with GPFS snapshots). If you don't set this option then the 'restore' button in the shadow copy UI will fail with a sharing violation.
shadow:snapprefixOptionaln/aRegular expression to match prefix of snapshot name. Red Hat Gluster Storage only supports Basic Regular Expression (BRE)
shadow:delimiterOptional_GMTdelimiter is used to separate shadow:snapprefix and shadow:format.
Following is an example of the smb.conf file:
[gluster-vol0]
comment = For samba share of volume vol0
vfs objects = shadow_copy2 glusterfs
glusterfs:volume = vol0
glusterfs:logfile = /var/log/samba/glusterfs-vol0.%M.log
glusterfs:loglevel = 3
path = /
read only = no
guest ok = yes
shadow:snapdir = /.snaps
shadow:basedir = /
shadow:sort = desc
shadow:snapprefix= ^S[A-Za-z0-9]*p$
shadow:format = _GMT-%Y.%m.%d-%H.%M.%S
In the above example, the mentioned parameters have to be added in the smb.conf file to enable shadow copy. The options mentioned are not mandatory.

Note

When configuring Shadow Copy with glusterfs_fuse modify the smb.conf file configurations.
For example:
vfs objects = shadow_copy2 glusterfs_fuse
[gluster-vol0]
comment = For samba share of volume vol0
vfs objects = shadow_copy2 glusterfs_fuse
path = /MOUNTDIR
read only = no
guest ok = yes
shadow:snapdir = /MOUNTDIR/.snaps
shadow:basedir = /MOUNTDIR
shadow:sort = desc
shadow:snapprefix= ^S[A-Za-z0-9]*p$
shadow:format = _GMT-%Y.%m.%d-%H.%M.%S
In the above example `MOUNTDIR` is a local FUSE moutpoint.
Shadow copy will filter all the snapshots based on the smb.conf entries. It will only show those snapshots which matches the criteria. In the example mentioned earlier, the snapshot name should start with an 'S' and end with 'p' and any alpha numeric characters in between is considered for the search. For example in the list of the following snapshots, the first two snapshots will be shown by Windows and the last one will be ignored. Hence, these options will help us filter out what snapshots to show and what not to.
Snap_GMT-2016.06.06-06.06.06
Sl123p_GMT-2016.07.07-07.07.07
xyz_GMT-2016.08.08-08.08.08
After editing the smb.conf file, execute the following steps to enable snapshot access:
  1. Start or restart the smb service.
    On RHEL 7 and RHEL 8, run systemctl [re]start smb
    On RHEL 6, run service smb [re]start
  2. Enable User Serviceable Snapshot (USS) for Samba. For more information see Section 8.13, “User Serviceable Snapshots”

6.4.8.2. Accessing Snapshot

To access snapshot on the Windows system, execute the following steps:
  1. Right Click on the file or directory for which the previous version is required.
  2. Click on Restore previous versions.
  3. In the dialog box, select the Date/Time of the previous version of the file, and select either Open, Restore, or Copy.
    where,
    Open: Lets you open the required version of the file in read-only mode.
    Restore: Restores the file back to the selected version.
    Copy: Lets you copy the file to a different location.
    Accessing Snapshot

    Figure 6.1. Accessing Snapshot

6.4.9. Tuning Performance

This section provides details regarding improving the system performance in an SMB environment. The various enhancements tasks can be classified into:
  • Enabling Metadata Caching to improve the performance of SMB access of Red Hat Gluster Storage volumes.
  • Enhancing Directory Listing Performance
  • Enhancing File/Directory Create Performance
More detailed information for each of this is provided in the sections ahead.

6.4.9.1. Enabling Metadata Caching

Enable metadata caching to improve the performance of directory operations. Execute the following commands from any one of the nodes on the trusted storage pool in the order mentioned below.

Note

If majority of the workload is modifying the same set of files and directories simultaneously from multiple clients, then enabling metadata caching might not provide the desired performance improvement.
  1. Execute the following command to enable metadata caching and cache invalidation:
    # gluster volume set <volname> group metadata-cache
    This is group set option which sets multiple volume options in a single command.
  2. To increase the number of files that can be cached, execute the following command:
    # gluster volume set <VOLNAME> network.inode-lru-limit <n>
    n, is set to 50000. It can be increased if the number of active files in the volume is very high. Increasing this number increases the memory footprint of the brick processes.

6.4.9.2. Enhancing Directory Listing Performance

The directory listing gets slower as the number of bricks/nodes increases in a volume, though the file/directory numbers remain unchanged. By enabling the parallel readdir volume option, the performance of directory listing is made independent of the number of nodes/bricks in the volume. Thus, the increase in the scale of the volume does not reduce the directory listing performance.

Note

You can expect an increase in performance only if the distribute count of the volume is 2 or greater and the size of the directory is small (< 3000 entries). The larger the volume (distribute count) greater is the performance benefit.
To enable parallel readdir execute the following commands:
  1. Verify if the performance.readdir-ahead option is enabled by executing the following command:
    # gluster volume get <VOLNAME> performance.readdir-ahead
    If the performance.readdir-ahead is not enabled then execute the following command:
    # gluster volume set <VOLNAME> performance.readdir-ahead on
  2. Execute the following command to enable parallel-readdir option:
    # gluster volume set <VOLNAME> performance.parallel-readdir on

    Note

    If there are more than 50 bricks in the volume it is recommended to increase the cache size to be more than 10Mb (default value):
    # gluster volume set <VOLNAME> performance.rda-cache-limit <CACHE SIZE>

6.4.9.3. Enhancing File/Directory Create Performance

Before creating / renaming any file, lookups (5-6 in SMB) are sent to verify if the file already exists. By serving these lookup from the cache when possible, increases the create / rename performance by multiple folds in SMB access.
  1. Execute the following command to enable negative-lookup cache:
     # gluster volume set <volname> group nl-cache
       volume set success

    Note

    The above command also enables cache-invalidation and increases the timeout to 10 minutes.

6.5. POSIX Access Control Lists

Basic Linux file system permissions are assigned based on three user types: the owning user, members of the owning group, and all other users. POSIX Access Control Lists (ACLs) work around the limitations of this system by allowing administrators to also configure file and directory access permissions based on any user and any group, rather than just the owning user and group.
This section covers how to view and set access control lists, and how to ensure this feature is enabled on your Red Hat Gluster Storage volumes. For more detailed information about how ACLs work, see the Red Hat Enterprise Linux 7 System Administrator's Guide: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/ch-Access_Control_Lists.html.

6.5.1. Setting ACLs with setfacl

The setfacl command lets you modify the ACLs of a specified file or directory. You can add access rules for a file with the -m subcommand, or remove access rules for a file with the -x subcommand. The basic syntax is as follows:
# setfacl subcommand access_rule file_path
The syntax of an access rule depends on which roles need to obey the rule.
Rules for users start with u:
# setfacl -m u:user:perms file_path
For example, setfacl -m u:fred:rw /mnt/data gives the user fred read and write access to the /mnt/data directory.
setfacl -x u::w /works_in_progress/my_presentation.txt prevents all users from writing to the /works_in_progress/my_presentation.txt file (except the owning user and members of the owning group, as these are controlled by POSIX).
Rules for groups start with g:
# setfacl -m g:group:perms file_path
For example, setfacl -m g:admins:rwx /etc/fstab gives users in the admins group read, write, and execute permissions to the /etc/fstab file.
setfacl -x g:newbies:x /mnt/harmful_script.sh prevents users in the newbies group from executing /mnt/harmful_script.sh.
Rules for other users start with o:
# setfacl -m o:perms file_path
For example, setfacl -m o:r /mnt/data/public gives users without any specific rules about their username or group permission to read files in the /mnt/data/public directory.
Rules for setting a maximum access level using an effective rights mask start with m:
# setfacl -m m:mask file_path
For example, setfacl -m m:r-x /mount/harmless_script.sh gives all users a maximum of read and execute access to the /mount/harmless_script.sh file.
You can set the default ACLs for a directory by adding d: to the beginning of any rule, or make a rule recursive with the -R option. For example, setfacl -Rm d:g:admins:rwx /etc gives all members of the admins group read, write, and execute access to any file created under the /etc directory after the point when setfacl is run.

6.5.2. Checking current ACLs with getfacl

The getfacl command lets you check the current ACLs of a file or directory. The syntax for this command is as follows:
# getfacl file_path
This prints a summary of current ACLs for that file. For example:
# getfacl /mnt/gluster/data/test/sample.jpg
# owner: antony
# group: antony
user::rw-
group::rw-
other::r--
If a directory has default ACLs set, these are prefixed with default:, like so:
# getfacl /mnt/gluster/data/doc
# owner: antony
# group: antony
user::rw-
user:john:r--
group::r--
mask::r--
other::r--
default:user::rwx
default:user:antony:rwx
default:group::r-x
default:mask::rwx
default:other::r-x

6.5.3. Mounting volumes with ACLs enabled

To mount a volume with ACLs enabled using the Native FUSE Client, use the acl mount option. For further information, see Section 6.2.3, “Mounting Red Hat Gluster Storage Volumes”.
ACLs are enabled by default on volumes mounted using the NFS and SMB access protocols. To check whether ACLs are enabled on other mounted volumes, see Section 6.5.4, “Checking ACL enablement on a mounted volume”.

6.5.4. Checking ACL enablement on a mounted volume

The following table shows you how to verify that ACLs are enabled on a mounted volume, based on the type of client your volume is mounted with.

Table 6.10. 

Client typeHow to checkFurther info
Native FUSE
Check the output of the mount command for the default_permissions option:
# mount | grep mountpoint
If default_permissions appears in the output for a mounted volume, ACLs are not enabled on that volume.
Check the output of the ps aux command for the gluster FUSE mount process (glusterfs):
# ps aux | grep gluster
root     30548  0.0  0.7 548408 13868 ?        Ssl  12:39   0:00 /usr/local/sbin/glusterfs --acl --volfile-server=127.0.0.2 --volfile-id=testvol /mnt/fuse_mnt
If --acl appears in the output for a mounted volume, ACLs are enabled on that volume.
See Section 6.2, “Native Client” for more information.
Gluster Native NFS
On the server side, check the output of the gluster volume info volname command. If nfs.acl appears in the output, that volume has ACLs disabled. If nfs.acl does not appear, ACLs are enabled (the default state).
On the client side, check the output of the mount command for the volume. If noacl appears in the output, ACLs are disabled on the mount point. If this does not appear in the output, the client checks that the server uses ACLs, and uses ACLs if server support is enabled.
Refer to the output of gluster volume set help pertaining to NFS, or see the Red Hat Enterprise Linux Storage Administration Guide for more information: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/ch-nfs.html
NFS Ganesha
On the server side, check the volume's export configuration file, /run/gluster/shared_storage/nfs-ganesha/exports/export.volname.conf. If the Disable_ACL option is set to true, ACLs are disabled. Otherwise, ACLs are enabled for that volume.

Note

NFS-Ganesha supports NFSv4 protocol standardized ACLs but not NFSACL protocol used for NFSv3 mounts. Only NFSv4 mounts can set ACLs.
There is no option to disable NFSv4 ACLs on the client side, so as long as the server supports ACLs, clients can set ACLs on the mount point.
See Section 6.3.3, “NFS Ganesha” for more information. For client side settings, refer to the Red Hat Enterprise Linux Storage Administration Guide: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/ch-nfs.html
samba
POSIX ACLs are enabled by default when using Samba to access a Red Hat Gluster Storage volume.
See Section 6.4, “SMB” for more information.

6.6. Checking Client Operating Versions

Different versions of Red Hat Gluster Storage support different features. Servers and clients identify the features that they are capable of supporting using an operating version number, or op-version. The cluster.op-version parameter sets the required operating version for all volumes in a cluster on the server side. Each client supports a range of operating versions that are identified by a minimum (min-op-version) and maximum (max-op-version) supported operating version.
Check the operating versions of the clients connected to a given volume by running the following command:
For Red Hat Gluster 3.2 and later
# gluster volume status volname clients
Use all in place of the name of your volume if you want to see the operating versions of clients connected to all volumes in the cluster.

Before Red Hat Gluster Storage 3.2:

  1. Perform a state dump for the volume whose clients you want to check.
    # gluster volume statedump volname
  2. Locate the state dump directory
    # gluster --print-statedumpdir
  3. Locate the state dump file and grep for client information.
    # grep -A4 "identifier=client_ip" statedumpfile

Chapter 7. Integrating Red Hat Gluster Storage with Windows Active Directory

In this chapter, the tasks necessary for integrating Red Hat Gluster Storage nodes into an existing Windows Active Directory domain are described. The following diagram describes the architecture of integrating Red Hat Gluster Storage with Windows Active Directory.
Active Directory Integration

Figure 7.1. Active Directory Integration

This section assumes that you have an active directory domain installed. Before we go ahead with the configuration details, following is a list of data along with examples that will be used in the sections ahead.

Table 7.1. Active Directory Integration information

InformationExample Value
DNS domain name / realmaddom.example.com
NetBIOS domain nameADDOM
Name of administrative accountadministrator
Red Hat Gluster Storage nodesrhs-srv1.addom.example.com, 192.168.56.10 rhs-srv2.addom.example.com, 192.168.56.11 rhs-srv3.addom.example.com, 192.168.56.12
Netbios name of the clusterRHS-SMB

7.1. Prerequisites

Before integration, the following steps have to be completed on an existing Red Hat Gluster Storage environment:
  • Name Resolution

    The Red Hat Gluster Storage nodes must be able to resolve names from the AD domain via DNS. To verify the same you can use the following command:

    host dc1.addom.example.com
    where, addom.example.com is the AD domain and dc1 is the name of a domain controller.
    For example, the /etc/resolv.conf file in a static network configuration could look like this:
    domain addom.example.com
    search addom.example.com
    nameserver 10.11.12.1 # dc1.addom.example.com
    nameserver 10.11.12.2 # dc2.addom.example.com
    This example assumes that both the domain controllers are also the DNS servers of the domain.
  • Kerberos Packages

    If you want to use the kerberos client utilities, like kinit and klist, then manually install the krb5-workstation using the following command:

    # yum -y install krb5-workstation
  • Synchronize Time Service

    It is essential that the time service on each Red Hat Gluster Storage node and the Windows Active Directory server are synchronized, else the Kerberos authentication may fail due to clock skew. In environments where time services are not reliable, the best practice is to configure the Red Hat Gluster Storage nodes to synchronize time from the Windows Server.

    On each Red Hat Storage node, edit the file /etc/ntp.conf for RHEL 7 or /etc/chrony.conf for RHEL 8 so the time is synchronized from a known, reliable time service:
    # Enable writing of statistics records.
    #statistics clockstats cryptostats loopstats peerstats
    server 0.rhel.pool.ntp.org iburst
    server 1.rhel.pool.ntp.org iburst
    
    driftfile /var/lib/chrony/drift
    makestep 1.0 3
    rtcsync
    logdir /var/log/chrony
    
    Activate the change on each Red Hat Gluster Storage node by stopping the NTP or chrony daemon, updating the time, then starting the chrony daemon. Verify the change on both servers using the following commands:
    For RHEL 7 and RHEL 8, run:
    # systemctl stop ntpd
    # systemctl start ntpd
    # systemctl stop chrony
    # systemctl start chrony
    For RHEL 6, run:
    # service ntpd stop
    # service ntpd start
    # service chrony stop
    # service chrony stop
  • Samba Packages

    Ensure to install the following Samba packages along with its dependencies:

    • CTDB
    • samba
    • samba-client
    • samba-winbind
    • samba-winbind-modules

7.2. Integration

Integrating Red Hat Gluster Storage Servers into an Active Directory domain involves the following series of steps:
  1. Configure Authentication
  2. Join Active Directory Domain
  3. Verify/Test Active Directory and Services

7.2.1. Configure Authentication

In order to join a cluster to the Active Directory domain, a couple of files have to be edited manually on all nodes.

Note

  • Ensure that CTDB is configured before the active directory join. For more information see, Section 6.3.1 Setting up CTDB for Samba in the Red Hat Gluster Storage Administration Guide.
  • It is recommended to take backups of the configuration and of Samba’s databases (local and ctdb) before making any changes.

7.2.1.1. Basic Samba Configuration

As of Red Hat Gluster Storage 3.4 Batch 4 Update, the recommended idmap configuration method for new deployments is autorid. Red Hat recommends autorid because in addition to automatically calculating user and group identifiers like tdb, it performs fewer database transactions and read operations, and is a prerequisite for supporting secure ID history (SID history).

Warning

Do not change the idmap configuration in existing deployments. Doing so requires a large number of changes, such as modifying the permissions and access control lists of all files in the shared file system, which unless done carefully can create user access problems. If you do need to change the idmap configuration settings for an existing deployment, contact Red Hat support for assistance.
The Samba configuration file /etc/samba/smb.conf must be identical on all nodes, and must contain the relevant parameters for AD. Along with that, a few other settings are required in order to activate mapping of user and group IDs.
The following example depicts the minimal Samba configuration for AD integration:
[global]
netbios name = RHS-SMB
workgroup = ADDOM
realm = addom.example.com
security = ads
clustering = yes
idmap config * : backend = autorid
idmap config * : range = 1000000-19999999
idmap config * : rangesize = 1000000

# -----------------RHS Options -------------------------
#
# The following line includes RHS-specific configuration options. Be careful with this line.

       include = /etc/samba/rhs-samba.conf

#=================Share Definitions =====================

Warning

The example above is the complete global section required in the smb.conf file. Ensure that nothing else appears in this section in order to prevent gluster mechanisms from changing settings when starting or stopping the ctdb lock volume.
The netbios name consists of only one name which has to be the same name on all cluster nodes. Windows clients will only access the cluster via that name (either in this short form or as an FQDN). The individual node hostname (rhs-srv1, rhs-srv2, …) must not be used for the netbios name parameter.

Note

  • The idmap range defines the lowerst and hightest identifier numbers that can be used. Specify a range large enough to cover the number of objects specified in rangesize.
  • The idmap rangesize specifies the number of identifiers available for each domain range. In this case there are one million identifiers per domain range, and the range parameter indicates that there are nearly 19 million identifiers total, meaning that there are a total of 19 possible domain ranges.
  • If you want to be able to use the individual host names to also access specific nodes, you can add them to the netbios aliases parameter of smb.conf.
  • In an AD environment, it is usually not required to run nmbd. However, if you have to run nmbd, then make sure to set the cluster addresses smb.conf option to the list of public IP addresses of the cluster.

7.2.1.2. Alternative Configuration using ad backend

If you need full control over Active Directory IDs, you can adapt the Samba configuration further by using the idmap_ad module in addition to autorid. The idmap_ad module reads the unix IDs from the AD's special unix attributes. This has to be configured by the AD domain's administrator before it can be used by Samba and winbind.
In order for Samba to use idmap_ad, the AD domain admin has to prepare the AD domain for using the so called unix extensions and assign unix IDs to all users and groups that should be able to access the Samba server.
For example, following is an extended Samba configuration file to use the idmap_ad backend for the ADDOM domain. The default autorid backend catches all objects from domains other than the ADDOM domain.
[global]
netbios name = RHS-SMB
workgroup = ADDOM
realm = addom.example.com
security = ads
clustering = yes
idmap config * : backend = autorid
idmap config * : range = 1000000-1999999
idmap config ADDOM : backend = ad
idmap config ADDOM : range = 3000000-3999999
idmap config ADDOM : schema mode = rfc2307
winbind nss info = rfc2307

# -------------------RHS Options -------------------------------
#
# The following line includes RHS-specific configuration options. Be careful with this line.

       include = /etc/samba/rhs-samba.conf

#===================Share Definitions =========================

Note

  • The range for the idmap_ad configuration is prescribed by the AD configuration. This has to be obtained by AD administrator.
  • Ranges for different idmap configurations must not overlap.
  • The schema mode and the winbind nss info setting should have the same value. If the domain is at level 2003R2 or newer, then rfc2307 is the correct value. For older domains, additional values sfu and sfu20 are available. See the manual pages of idmap_ad and smb.conf for further details.

7.2.1.3. Verifying the Samba Configuration

Test the new configuration file using the testparm command. For example:
# testparm -s
Load smb config files from /etc/samba/smb.conf
rlimit_max: increasing rlimit_max (1024) to minimum Windows limit (16384)
Loaded services file OK.

Server role: ROLE_DOMAIN_MEMBER

# Global parameters
[global]
    workgroup = ADDOM
    realm = addom.example.com
    netbios name = RHS-SMB
    security = ADS
    clustering = Yes
    winbind nss info = rfc2307
    idmap config addom : schema mode = rfc2307
    idmap config addom : range = 3000000-3999999
    idmap config addom : backend = ad
    idmap config * : range = 1000000-1999999
    idmap config * : backend = autorid

7.2.1.4. nsswitch Configuration

Once the Samba configuration has been made, Samba has to be enabled to use the mapped users and groups from AD. This is achieved via the local Name Service Switch (NSS) that has to be made aware of the winbind. To use the winbind NSS module, edit the /etc/nsswitch.conf file. Make sure the file contains the winbind entries for the passwd and group databases. For example:
...
passwd: files winbind
group: files winbind
...
This will enable the use of winbind and should make users and groups visible on the individual cluster node once Samba is joined to AD and winbind is started.

7.2.2. Join Active Directory Domain

Prior to joining AD, CTDB must be started so that the machine account information can be stored in a database file that is available on all cluster nodes via CTDB. In addition to that, all other Samba services should be stopped. If key-based SSH authentication without a password has been configured for the root user between the nodes, you can use the onnode tool to run these commands on all nodes from a single node:
For RHEL 7 and RHEL 8, run:
# onnode all systemctl start ctdb
# onnode all systemctl stop winbind
# onnode all systemctl stop smb
For RHEL 6, run:
# onnode all service ctdb start
# onnode all service winbind stop
# onnode all service smb stop

Note

  • If your configuration has CTDB managing Winbind and Samba, they can be temporarily disabled with the following commands (to be executed prior to the above stop commands) so as to prevent CTDB going into an unhealthy state when they are shut down:
    # onnode all ctdb event script disable legacy 49.winbind
    # onnode all ctdb event script disable legacy 50.samba
    
  • For some versions of Red Hat Gluster Storage, a bug in the selinux policy prevents 'ctdb disablescript SCRIPT' from succeeding. If this is the case, 'chmod -x /etc/ctdb/events.d/SCRIPT' can be executed as a workaround from a root shell.
  • Shutting down winbind and smb is primarily to prevent access to SMB services during this AD integration. These services may be left running but access to them should be prevented through some other means.
The join is initiated via the net utility from a single node:

Warning

The following step must be executed only on one cluster node and should not be repeated on other cluster nodes. CTDB makes sure that the whole cluster is joined by this step.
# net ads join -U Administrator
Enter Administrator's password:
Using short domain name -- ADDOM
Joined 'RHS-SMB' to dns domain addom.example.com'
Not doing automatic DNS update in a clustered setup.
Once the join is successful, the cluster ip addresses and the cluster netbios name should be made public in the network. For registering multiple public cluster IP addresses in the AD DNS server, the net utility can be used again:
# net ads dns register rhs-smb <PUBLIC IP 1> <PUBLIC IP 2> ...
This command will make sure the DNS name rhs-smb will resolve to the given public IP addresses. The DNS registrations use the cluster machine account for authentication in AD, which means this operation only can be done after the join has succeeded.
Registering the NetBIOS name of the cluster is done by the nmbd service. In order to make sure that the nmbd instances on the hosts don’t overwrite each other’s registrations, the ‘cluster addresses’ smb.conf option should be set to the list of public addresses of the whole cluster.

7.2.3. Verify/Test Active Directory and Services

When the join is successful, the Samba and the Winbind daemons can be started.
Start nmdb, winbind and smb services using the following commands:
For RHEL 7 and RHEL 8, run:
# onnode all systemctl start nmb
# onnode all systemctl start winbind
# onnode all systemctl start smb
For RHEL 6, run:
# onnode all service nmb start
# onnode all service winbind start
# onnode all service smb start

Note

  • If you previously disabled CTDB’s ability to manage Winbind and Samba they can be re-enabled with the following commands:
    # onnode all ctdb event script enable legacy 50.samba
    # onnode all ctdb event script enable legacy 49.winbind
  • With the latest ctdb-4.9.8-105.el7rhgs.x86_64 package, the paths of ctdb managed service scripts have changed. The script files are now available under /etc/ctdb/events/legacy/ after enabling them from /usr/share/ctdb/events/legacy.
  • To enable ctdb event script, execute the following command:
    ctdb event script enable legacy 49.winbind
  • To enable ctbd event script on all nodes, execute the following command:
    # onnode all ctdb event script enable legacy 49.winbind
Execute the following verification steps:
  1. Verify the join by executing the following steps

    Verify the join to check if the created machine account can be used to authenticate to the AD LDAP server using the following command:
    # net ads testjoin
    Join is OK
  2. Execute the following command to display the machine account’s LDAP object
    # net ads status -P
    objectClass: top
    objectClass: person
    objectClass: organizationalPerson
    objectClass: user
    objectClass: computer
    cn: rhs-smb
    distinguishedName: CN=rhs-smb,CN=Computers,DC=addom,DC=example,DC=com
    instanceType: 4
    whenCreated: 20150922013713.0Z
    whenChanged: 20151126111120.0Z
    displayName: RHS-SMB$
    uSNCreated: 221763
    uSNChanged: 324438
    name: rhs-smb
    objectGUID: a178177e-4aa4-4abc-9079-d1577e137723
    userAccountControl: 69632
    badPwdCount: 0
    codePage: 0
    countryCode: 0
    badPasswordTime: 130880426605312806
    lastLogoff: 0
    lastLogon: 130930100623392945
    localPolicyFlags: 0
    pwdLastSet: 130930098809021309
    primaryGroupID: 515
    objectSid: S-1-5-21-2562125317-1564930587-1029132327-1196
    accountExpires: 9223372036854775807
    logonCount: 1821
    sAMAccountName: rhs-smb$
    sAMAccountType: 805306369
    dNSHostName: rhs-smb.addom.example.com
    servicePrincipalName: HOST/rhs-smb.addom.example.com
    servicePrincipalName: HOST/RHS-SMB
    objectCategory: CN=Computer,CN=Schema,CN=Configuration,DC=addom,DC=example,DC=com
    isCriticalSystemObject: FALSE
    dSCorePropagationData: 16010101000000.0Z
    lastLogonTimestamp: 130929563322279307
    msDS-SupportedEncryptionTypes: 31
    
  3. Execute the following command to display general information about the AD server:
    # net ads info
    LDAP server: 10.11.12.1
    LDAP server name: dc1.addom.example.com
    Realm: ADDOM.EXAMPLE.COM
    Bind Path: dc=ADDOM,dc=EXAMPLE,dc=COM
    LDAP port: 389
    Server time: Thu, 26 Nov 2015 11:15:04 UTC
    KDC server: 10.11.12.1
    Server time offset: -26
  4. Verify if winbind is operating correctly by executing the following steps

    Execute the following command to verify if winbindd can use the machine account for authentication to AD
    # wbinfo -t
    checking the trust secret for domain ADDOM via RPC calls succeeded
  5. Execute the following command to resolve the given name to a Windows SID
    # wbinfo --name-to-sid 'ADDOM\Administrator'
    S-1-5-21-2562125317-1564930587-1029132327-500 SID_USER (1)
  6. Execute the following command to verify authentication:
    # wbinfo -a 'ADDOM\user'
    Enter ADDOM\user's password:
    plaintext password authentication succeeded
    Enter ADDOM\user's password:
    challenge/response password authentication succeeded
    or,
    # wbinfo -a 'ADDOM\user%password'
    plaintext password authentication succeeded
    challenge/response password authentication succeeded
  7. Execute the following command to verify if the id-mapping is working properly:
    # wbinfo --sid-to-uid <SID-OF-ADMIN>
    1000000
  8. Execute the following command to verify if the winbind Name Service Switch module works correctly:
    # getent passwd 'ADDOM\Administrator'
    ADDOM\administrator:*:1000000:1000004::/home/ADDOM/administrator:/bin/false
  9. Execute the following command to verify if samba can use winbind and the NSS module correctly:
    # smbclient -L rhs-smb -U 'ADDOM\Administrator'
    Domain=[ADDOM] OS=[Windows 6.1] Server=[Samba 4.2.4]
    
            Sharename       Type      Comment
            ---------       ----      -------
            IPC$            IPC       IPC Service (Samba 4.2.4)
    Domain=[ADDOM] OS=[Windows 6.1] Server=[Samba 4.2.4]
    
            Server               Comment
            ---------            -------
            RHS-SMB         Samba 4.2.4
    
            Workgroup            Master
            ---------            -------
            ADDOM             RHS-SMB
    

Part IV. Manage

Chapter 8. Managing Snapshots

Red Hat Gluster Storage Snapshot feature enables you to create point-in-time copies of Red Hat Gluster Storage volumes, which you can use to protect data. Users can directly access Snapshot copies which are read-only to recover from accidental deletion, corruption, or modification of the data.
Description

Figure 8.1. Snapshot Architecture

In the Snapshot Architecture diagram, Red Hat Gluster Storage volume consists of multiple bricks (Brick1 Brick2 etc) which is spread across one or more nodes and each brick is made up of independent thin Logical Volumes (LV). When a snapshot of a volume is taken, it takes the snapshot of the LV and creates another brick. Brick1_s1 is an identical image of Brick1. Similarly, identical images of each brick is created and these newly created bricks combine together to form a snapshot volume.
Some features of snapshot are:
  • Crash Consistency

    A crash consistent snapshot is captured at a particular point-in-time. When a crash consistent snapshot is restored, the data is identical as it was at the time of taking a snapshot.

    Note

    Currently, application level consistency is not supported.
  • Online Snapshot

    Snapshot is an online snapshot hence the file system and its associated data continue to be available for the clients even while the snapshot is being taken.

  • Barrier

    To guarantee crash consistency some of the file operations are blocked during a snapshot operation.

    These file operations are blocked till the snapshot is complete. All other file operations are passed through. There is a default time-out of 2 minutes, within that time if snapshot is not complete then these file operations are unbarriered. If the barrier is unbarriered before the snapshot is complete then the snapshot operation fails. This is to ensure that the snapshot is in a consistent state.

Note

Taking a snapshot of a Red Hat Gluster Storage volume that is hosting the Virtual Machine Images is not recommended. Taking a Hypervisor assisted snapshot of a virtual machine would be more suitable in this use case.

8.1. Prerequisites

Before using this feature, ensure that the following prerequisites are met:
Recommended Setup

The recommended setup for using Snapshot is described below. In addition, you must ensure to read Chapter 19, Tuning for Performance for enhancing snapshot performance:
  • For each volume brick, create a dedicated thin pool that contains the brick of the volume and its (thin) brick snapshots. With the current thin-p design, avoid placing the bricks of different Red Hat Gluster Storage volumes in the same thin pool, as this reduces the performance of snapshot operations, such as snapshot delete, on other unrelated volumes.
  • The recommended thin pool chunk size is 256KB. There might be exceptions to this in cases where we have a detailed information of the customer's workload.
  • The recommended pool metadata size is 0.1% of the thin pool size for a chunk size of 256KB or larger. In special cases, where we recommend a chunk size less than 256KB, use a pool metadata size of 0.5% of thin pool size.
For Example

To create a brick from device /dev/sda1.
  1. Create a physical volume(PV) by using the pvcreate command.
    pvcreate /dev/sda1
    Use the correct dataalignment option based on your device. For more information, Section 19.2, “Brick Configuration”
  2. Create a Volume Group (VG) from the PV using the following command:
    vgcreate dummyvg /dev/sda1
  3. Create a thin-pool using the following command:
    # lvcreate --size 1T --thin dummyvg/dummypool --chunksize 256k --poolmetadatasize 16G  --zero n
    A thin pool of size 1 TB is created, using a chunksize of 256 KB. Maximum pool metadata size of 16 G is used.
  4. Create a thinly provisioned volume from the previously created pool using the following command:
    # lvcreate --virtualsize 1G --thin dummyvg/dummypool --name dummylv
  5. Create a file system (XFS) on this. Use the recommended options to create the XFS file system on the thin LV.
    For example,
    mkfs.xfs -f -i size=512 -n size=8192 /dev/dummyvg/dummylv
  6. Mount this logical volume and use the mount path as the brick.
    mount /dev/dummyvg/dummylv /mnt/brick1

8.2. Creating Snapshots

Before creating a snapshot ensure that the following prerequisites are met:
  • Red Hat Gluster Storage volume has to be present and the volume has to be in the Started state.
  • All the bricks of the volume have to be on an independent thin logical volume(LV).
  • Snapshot names must be unique in the cluster.
  • All the bricks of the volume should be up and running, unless it is a n-way replication where n >= 3. In such case quorum must be met. For more information see Chapter 8, Managing Snapshots
  • No other volume operation, like rebalance, add-brick, etc, should be running on the volume.
  • Total number of snapshots in the volume should not be equal to Effective snap-max-hard-limit. For more information see Configuring Snapshot Behavior.
  • If you have a geo-replication setup, then pause the geo-replication session if it is running, by executing the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL pause
    For example,
    # gluster volume geo-replication master-vol example.com::slave-vol pause
    Pausing geo-replication session between master-vol example.com::slave-vol has been successful
    Ensure that you take the snapshot of the master volume and then take snapshot of the slave volume.
To create a snapshot of the volume, run the following command:
# gluster snapshot create <snapname> <volname> [no-timestamp] [description <description>] [force]
where,
  • snapname - Name of the snapshot that will be created.
  • VOLNAME(S) - Name of the volume for which the snapshot will be created. We only support creating snapshot of single volume.
  • description - This is an optional field that can be used to provide a description of the snap that will be saved along with the snap.
  • force - The behavior of snapshot creation command remains the same with and without the force option.
  • no-timestamp: By default a timestamp is appended to the snapshot name. If you do not want to append timestamp then pass no-timestamp as an argument.

Note

Snapshots are not activated on creation by default; to enable this behavior for all future snapshot creations, set the activate-on-create parameter to enabled.
For Example 1:
# gluster snapshot create snap1 vol1 no-timestamp
snapshot create: success: Snap snap1 created successfully
For Example 2:
# gluster snapshot create snap1 vol1
snapshot create: success: Snap snap1_GMT-2015.07.20-10.02.33 created successfully
Snapshot of a Red Hat Gluster Storage volume creates a read-only Red Hat Gluster Storage volume. This volume will have identical configuration as of the original / parent volume. Bricks of this newly created snapshot is mounted as /var/run/gluster/snaps/<snap-volume-name>/brick<bricknumber>.
For example, a snapshot with snap volume name 0888649a92ea45db8c00a615dfc5ea35 and having two bricks will have the following two mount points:
/var/run/gluster/snaps/0888649a92ea45db8c00a615dfc5ea35/brick1
/var/run/gluster/snaps/0888649a92ea45db8c00a615dfc5ea35/brick2
These mounts can also be viewed using the df or mount command.

Note

If you have a geo-replication setup, after creating the snapshot, resume the geo-replication session by running the following command:
# gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL resume
For example,
# gluster volume geo-replication master-vol example.com::slave-vol resume
Resuming geo-replication session between master-vol example.com::slave-vol has been successful
Volume snapshot creation results in the creation of snapshot pool of blocks that contains a copy of the LVM metadata. After taking a snapshot, when new data is written to gluster volume, the snapshot pool is overwritten and the changes are copied to the main gluster volume. As a result, the snapshot pool consumes more metadata space if data changes after the snapshot is taken.

8.3. Cloning a Snapshot

A clone or a writable snapshot is a new volume, which is created from a particular snapshot.
To clone a snapshot, execute the following command.
# gluster snapshot clone <clonename> <snapname>
where,
clonename: It is the name of the clone, ie, the new volume that will be created.
snapname: It is the name of the snapshot that is being cloned.

Note

  • Unlike restoring a snapshot, the original snapshot is still retained, after it has been cloned.
  • The snapshot should be in activated state and all the snapshot bricks should be in running state before taking clone. Also the server nodes should be in quorum.
  • This is a space efficient clone therefore both the Clone (new volume) and the snapshot LVM share the same LVM backend. The space consumption of the LVM grow as the new volume (clone) diverge from the snapshot.
For example:
# gluster snapshot clone clone_vol snap1
snapshot clone: success: Clone clone_vol created successfully
To check the status of the newly cloned snapshot execute the following command
# gluster vol info <clonename>
For example:
# gluster vol info clone_vol

Volume Name: clone_vol
Type: Distribute
Volume ID: cdd59995-9811-4348-8e8d-988720db3ab9
Status: Created
Number of Bricks: 1
Transport-type: tcp
Bricks:
Brick1: 10.00.00.01:/var/run/gluster/snaps/clone_vol/brick1/brick3
Options Reconfigured:
performance.readdir-ahead: on
In the example it is observed that clone is in Created state, similar to a newly created volume. This volume should be explicitly started to use this volume.

8.4. Listing of Available Snapshots

To list all the snapshots that are taken for a specific volume, run the following command:
# gluster snapshot list [VOLNAME]
where,
  • VOLNAME - This is an optional field and if provided lists the snapshot names of all snapshots present in the volume.
For Example:
# gluster snapshot list
snap3
# gluster snapshot list test_vol
No snapshots present

8.5. Getting Information of all the Available Snapshots

The following command provides the basic information of all the snapshots taken. By default the information of all the snapshots in the cluster is displayed:
# gluster snapshot info [(<snapname> | volume VOLNAME)]
where,
  • snapname - This is an optional field. If the snapname is provided then the information about the specified snap is displayed.
  • VOLNAME - This is an optional field. If the VOLNAME is provided the information about all the snaps in the specified volume is displayed.
For Example:
# gluster snapshot info snap3
Snapshot                  : snap3
Snap UUID                 : b2a391ce-f511-478f-83b7-1f6ae80612c8
Created                   : 2014-06-13 09:40:57
Snap Volumes:

     Snap Volume Name          : e4a8f4b70a0b44e6a8bff5da7df48a4d
     Origin Volume name        : test_vol1
     Snaps taken for test_vol1      : 1
     Snaps available for test_vol1  : 255
     Status                    : Started

8.6. Getting the Status of Available Snapshots

This command displays the running status of the snapshot. By default the status of all the snapshots in the cluster are displayed. To check the status of all the snapshots that are taken for a particular volume, specify a volume name:
# gluster snapshot status [(<snapname> | volume VOLNAME)]
where,
  • snapname - This is an optional field. If the snapname is provided then the status about the specified snap is displayed.
  • VOLNAME - This is an optional field. If the VOLNAME is provided the status about all the snaps in the specified volume is displayed.
For example:
# gluster snapshot status snap3

Snap Name : snap3
Snap UUID : b2a391ce-f511-478f-83b7-1f6ae80612c8

     Brick Path        :
10.70.42.248:/var/run/gluster/snaps/e4a8f4b70a0b44e6a8bff5da7df48a4d/brick1/brick1
     Volume Group      :   snap_lvgrp1
     Brick Running     :   Yes
     Brick PID         :   1640
     Data Percentage   :   1.54
     LV Size           :   616.00m


     Brick Path        :
10.70.43.139:/var/run/gluster/snaps/e4a8f4b70a0b44e6a8bff5da7df48a4d/brick2/brick3
     Volume Group      :   snap_lvgrp1
     Brick Running     :   Yes
     Brick PID         :   3900
     Data Percentage   :   1.80
     LV Size           :   616.00m


     Brick Path        :
10.70.43.34:/var/run/gluster/snaps/e4a8f4b70a0b44e6a8bff5da7df48a4d/brick3/brick4
     Volume Group      :   snap_lvgrp1
     Brick Running     :   Yes
     Brick PID         :   3507
     Data Percentage   :   1.80
     LV Size           :   616.00m

Note

This shows the status of an activated snapshot.

8.7. Configuring Snapshot Behavior

The configurable parameters for snapshot are:
  • snap-max-hard-limit: If the snapshot count in a volume reaches this limit then no further snapshot creation is allowed. The range is from 1 to 256. Once this limit is reached you have to remove the snapshots to create further snapshots. This limit can be set for the system or per volume. If both system limit and volume limit is configured then the effective max limit would be the lowest of the two value.
  • snap-max-soft-limit: This is a percentage value. The default value is 90%. This configuration works along with auto-delete feature. If auto-delete is enabled then it will delete the oldest snapshot when snapshot count in a volume crosses this limit. When auto-delete is disabled it will not delete any snapshot, but it will display a warning message to the user.
  • auto-delete: This will enable or disable auto-delete feature. By default auto-delete is disabled. When enabled it will delete the oldest snapshot when snapshot count in a volume crosses the snap-max-soft-limit. When disabled it will not delete any snapshot, but it will display a warning message to the user
  • activate-on-create: Snapshots are not activated at creation time by default. If you want created snapshots to immediately be activated after creation, set the activate-on-create parameter to enabled. Note that all volumes are affected by this setting.
  • Displaying the Configuration Values

    To display the existing configuration values for a volume or the entire cluster, run the following command:

    # gluster snapshot config [VOLNAME]
    where:
    • VOLNAME: This is an optional field. The name of the volume for which the configuration values are to be displayed.
    If the volume name is not provided then the configuration values of all the volume is displayed. System configuration details are displayed irrespective of whether the volume name is specified or not.
    For Example:
    # gluster snapshot config
    
    Snapshot System Configuration:
    snap-max-hard-limit : 256
    snap-max-soft-limit : 90%
    auto-delete : disable
    activate-on-create : disable
    
    Snapshot Volume Configuration:
    
    Volume : test_vol
    snap-max-hard-limit : 256
    Effective snap-max-hard-limit : 256
    Effective snap-max-soft-limit : 230 (90%)
    
    Volume : test_vol1
    snap-max-hard-limit : 256
    Effective snap-max-hard-limit : 256
    Effective snap-max-soft-limit : 230 (90%)
  • Changing the Configuration Values

    To change the existing configuration values, run the following command:

    # gluster snapshot config [VOLNAME] ([snap-max-hard-limit <count>] [snap-max-soft-limit <percent>]) | ([auto-delete <enable|disable>]) | ([activate-on-create <enable|disable>])
    where:
    • VOLNAME: This is an optional field. The name of the volume for which the configuration values are to be changed. If the volume name is not provided, then running the command will set or change the system limit.
    • snap-max-hard-limit: Maximum hard limit for the system or the specified volume.
    • snap-max-soft-limit: Soft limit mark for the system.
    • auto-delete: This enables or disables the auto-delete feature. By default auto-delete is disabled.
    • activate-on-create: This enables or disables the activate-on-create feature for all volumes. By default activate-on-create is disabled.
    For Example:
    # gluster snapshot config test_vol snap-max-hard-limit 100
    Changing snapshot-max-hard-limit will lead to deletion of snapshots if
    they exceed the new limit.
    Do you want to continue? (y/n) y
    snapshot config: snap-max-hard-limit for test_vol set successfully

8.8. Activating and Deactivating a Snapshot

Only activated snapshots are accessible. Check the Accessing Snapshot section for more details. Since each snapshot is a Red Hat Gluster Storage volume it consumes some resources hence if the snapshots are not needed it would be good to deactivate them and activate them when required. To activate a snapshot run the following command:
# gluster snapshot activate <snapname> [force]
where:
  • snapname: Name of the snap to be activated.
  • force: If some of the bricks of the snapshot volume are down then use the force command to start them.
For Example:
# gluster snapshot activate snap1
To deactivate a snapshot, run the following command:
# gluster snapshot deactivate <snapname>
where:
  • snapname: Name of the snap to be deactivated.
For example:
# gluster snapshot deactivate snap1

8.9. Deleting Snapshot

Before deleting a snapshot ensure that the following prerequisites are met:
  • Snapshot with the specified name should be present.
  • Red Hat Gluster Storage nodes should be in quorum.
  • No volume operation (e.g. add-brick, rebalance, etc) should be running on the original / parent volume of the snapshot.
To delete a snapshot run the following command:
# gluster snapshot delete <snapname>
where,
  • snapname - The name of the snapshot to be deleted.
For Example:
# gluster snapshot delete snap2
Deleting snap will erase all the information about the snap. Do you still want to continue? (y/n) y
snapshot delete: snap2: snap removed successfully

Note

Red Hat Gluster Storage volume cannot be deleted if any snapshot is associated with the volume. You must delete all the snapshots before issuing a volume delete.

8.9.1. Deleting Multiple Snapshots

Multiple snapshots can be deleted using either of the following two commands.
To delete all the snapshots present in a system, execute the following command:
# gluster snapshot delete all
To delete all the snapshot present in a specified volume, execute the following command:
# gluster snapshot delete volume <volname>

8.10. Restoring Snapshot

Before restoring a snapshot ensure that the following prerequisites are met
  • The specified snapshot has to be present
  • The original / parent volume of the snapshot has to be in a stopped state.
  • Red Hat Gluster Storage nodes have to be in quorum.
  • No volume operation (e.g. add-brick, rebalance, etc) should be running on the origin or parent volume of the snapshot.
    # gluster snapshot restore <snapname>
    where,
    • snapname - The name of the snapshot to be restored.
    For Example:
    # gluster snapshot restore snap1
    Snapshot restore: snap1: Snap restored successfully
    After snapshot is restored and the volume is started, trigger a self-heal by running the following command:
    # gluster volume heal VOLNAME full

    Note

  • In the cluster, identify the nodes participating in the snapshot with the snapshot status command. For example:
     # gluster snapshot status snapname
    
        Snap Name : snapname
        Snap UUID : bded7c02-8119-491b-a7e1-cc8177a5a1cd
    
         Brick Path        :   10.70.43.46:/var/run/gluster/snaps/816e8403874f43a78296decd7c127205/brick2/brick2
         Volume Group      :   snap_lvgrp
         Brick Running     :   Yes
         Brick PID         :   8303
         Data Percentage   :   0.43
         LV Size           :   2.60g
    
    
         Brick Path        :   10.70.42.33:/var/run/gluster/snaps/816e8403874f43a78296decd7c127205/brick3/brick3
         Volume Group      :   snap_lvgrp
         Brick Running     :   Yes
         Brick PID         :   4594
         Data Percentage   :   42.63
         LV Size           :   2.60g
    
    
         Brick Path        :   10.70.42.34:/var/run/gluster/snaps/816e8403874f43a78296decd7c127205/brick4/brick4
         Volume Group      :   snap_lvgrp
         Brick Running     :   Yes
         Brick PID         :   23557
         Data Percentage   :   12.41
         LV Size           :   2.60g
    
    • In the nodes identified above, check if the geo-replication repository is present in /var/lib/glusterd/snaps/snapname. If the repository is present in any of the nodes, ensure that the same is present in /var/lib/glusterd/snaps/snapname throughout the cluster. If the geo-replication repository is missing in any of the nodes in the cluster, copy it to /var/lib/glusterd/snaps/snapname in that node.
    • Restore snapshot of the volume using the following command:
      # gluster snapshot restore snapname
Restoring Snapshot of a Geo-replication Volume

If you have a geo-replication setup, then perform the following steps to restore snapshot:

  1. Stop the geo-replication session.
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop
  2. Stop the slave volume and then the master volume.
    # gluster volume stop VOLNAME
  3. Restore snapshot of the slave volume and the master volume.
    # gluster snapshot restore snapname
  4. Start the slave volume first and then the master volume.
    # gluster volume start VOLNAME
  5. Start the geo-replication session.
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start
    
  6. Resume the geo-replication session.
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL resume
    

8.11. Accessing Snapshots

Snapshot of a Red Hat Gluster Storage volume can be accessed only via FUSE mount. Use the following command to mount the snapshot.
mount -t glusterfs <hostname>:/snaps/<snapname>/parent-VOLNAME /mount_point
  • parent-VOLNAME - Volume name for which we have created the snapshot.
    For example,
    # mount -t glusterfs myhostname:/snaps/snap1/test_vol /mnt
Since the Red Hat Gluster Storage snapshot volume is read-only, no write operations are allowed on this mount. After mounting the snapshot the entire snapshot content can then be accessed in a read-only mode.

Note

NFS and CIFS mount of snapshot volume is not supported.
Snapshots can also be accessed via User Serviceable Snapshots. For more information see, Section 8.13, “User Serviceable Snapshots”

Warning

External snapshots, such as snapshots of a virtual machine/instance, where Red Hat Gluster Storage Server is installed as a guest OS or FC/iSCSI SAN snapshots are not supported.

8.12. Scheduling of Snapshots

Snapshot scheduler creates snapshots automatically based on the configured scheduled interval of time. The snapshots can be created every hour, a particular day of the month, particular month, or a particular day of the week based on the configured time interval. The following sections describes scheduling of snapshots in detail.

8.12.1. Prerequisites

  • To initialize snapshot scheduler on all the nodes of the cluster, execute the following command:
    snap_scheduler.py init
    
    This command initializes the snap_scheduler and interfaces it with the crond running on the local node. This is the first step, before executing any scheduling related commands from a node.

    Note

    This command has to be run on all the nodes participating in the scheduling. Other options can be run independently from any node, where initialization has been successfully completed.
  • A shared storage named gluster_shared_storage is used across nodes to co-ordinate the scheduling operations. This shared storage is mounted at /var/run/gluster/shared_storage on all the nodes. For more information see, Section 11.12, “Setting up Shared Storage Volume”

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
  • All nodes in the cluster have their times synced using NTP or any other mechanism. This is a hard requirement for this feature to work.
  • If you are on Red Hat Enterprise Linux 7.1 or later, set the cron_system_cronjob_use_shares boolean to on by running the following command:
    # setsebool -P cron_system_cronjob_use_shares on
    

8.12.2. Snapshot Scheduler Options

Note

There is a latency of one minute, between providing a command by the helper script and for the command to take effect. Hence, currently, we do not support snapshot schedules with per minute granularity.
Enabling Snapshot Scheduler

To enable snap scheduler, execute the following command:

snap_scheduler.py enable

Note

Snapshot scheduler is disabled by default after initialization
For example:
# snap_scheduler.py enable
snap_scheduler: Snapshot scheduling is enabled
Disabling Snapshot Scheduler

To enable snap scheduler, execute the following command:

 snap_scheduler.py disable
For example:
# snap_scheduler.py disable
snap_scheduler: Snapshot scheduling is disabled
Displaying the Status of Snapshot Scheduler

To display the the current status(Enabled/Disabled) of the snap scheduler, execute the following command:

snap_scheduler.py status
For example:
# snap_scheduler.py status
snap_scheduler: Snapshot scheduling status: Disabled
Adding a Snapshot Schedule

To add a snapshot schedule, execute the following command:

snap_scheduler.py add "Job Name" "Schedule" "Volume Name"
where,
Job Name: This name uniquely identifies this particular schedule, and can be used to reference this schedule for future events like edit/delete. If a schedule already exists for the specified Job Name, the add command will fail.
Schedule: The schedules are accepted in the format crond understands. For example:
Example of job definition:
.---------------- minute (0 - 59)
| .------------- hour (0 - 23)
| | .---------- day of month (1 - 31)
| | | .------- month (1 - 12) OR jan,feb,mar,apr ...
| | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
| | | | |
* * * * * user-name command to be executed
Volume name: The name of the volume on which the scheduled snapshot operation will be performed
For example:
# snap_scheduler.py add "Job1" "* * * * *" test_vol
snap_scheduler: Successfully added snapshot schedule

Note

The snapshots taken by the scheduler will have the following naming convention: Scheduler-<Job Name>-<volume name>_<Timestamp>.
For example:
Scheduled-Job1-test_vol_GMT-2015.06.19-09.47.01
Editing a Snapshot Schedule

To edit an existing snapshot schedule, execute the following command:

snap_scheduler.py edit "Job Name" "Schedule" "Volume Name"
where,
Job Name: This name uniquely identifies this particular schedule, and can be used to reference this schedule for future events like edit/delete. If a schedule already exists for the specified Job Name, the add command will fail.
Schedule: The schedules are accepted in the format crond understands. For example:
Example of job definition:
.---------------- minute (0 - 59)
| .------------- hour (0 - 23)
| | .---------- day of month (1 - 31)
| | | .------- month (1 - 12) OR jan,feb,mar,apr ...
| | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
| | | | |
* * * * * user-name command to be executed
Volume name: The name of the volume on which the snapshot schedule will be edited.
For Example:
# snap_scheduler.py edit "Job1" "*/5 * * * *" gluster_shared_storage
snap_scheduler: Successfully edited snapshot schedule
Listing a Snapshot Schedule

To list the existing snapshot schedule, execute the following command:

snap_scheduler.py list
For example:
# snap_scheduler.py list
JOB_NAME         SCHEDULE         OPERATION        VOLUME NAME
--------------------------------------------------------------------
Job0                          * * * * *                Snapshot Create    test_vol
Deleting a Snapshot Schedule

To delete an existing snapshot schedule, execute the following command:

snap_scheduler.py delete "Job Name"
where,
Job Name: This name uniquely identifies the particular schedule that has to be deleted.
For example:
# snap_scheduler.py delete Job1
snap_scheduler: Successfully deleted snapshot schedule

8.13. User Serviceable Snapshots

User Serviceable Snapshot is a quick and easy way to access data stored in snapshotted volumes. This feature is based on the core snapshot feature in Red Hat Gluster Storage. With User Serviceable Snapshot feature, you can access the activated snapshots of the snapshot volume.
Consider a scenario where a user wants to access a file test.txt which was in the Home directory a couple of months earlier and was deleted accidentally. You can now easily go to the virtual .snaps directory that is inside the home directory and recover the test.txt file using the cp command.

Note

  • User Serviceable Snapshot is not the recommended option for bulk data access from an earlier snapshot volume. For such scenarios it is recommended to mount the Snapshot volume and then access the data. For more information see, Chapter 8, Managing Snapshots
  • Each activated snapshot volume when initialized by User Serviceable Snapshots, consumes some memory. Most of the memory is consumed by various house keeping structures of gfapi and xlators like DHT, AFR, etc. Therefore, the total memory consumption by snapshot depends on the number of bricks as well. Each brick consumes approximately 10MB of space, for example, in a 4x3 replica setup the total memory consumed by snapshot is around 50MB and for a 6x3 setup it is roughly 90MB.
    Therefore, as the number of active snapshots grow, the total memory footprint of the snapshot daemon (snapd) also grows. Therefore, in a low memory system, the snapshot daemon can get OOM killed if there are too many active snapshots

8.13.1. Enabling and Disabling User Serviceable Snapshot

To enable user serviceable snapshot, run the following command:
# gluster volume set VOLNAME features.uss enable
For example:
# gluster volume set test_vol features.uss enable
volume set: success
Activate the snapshot to access it via the user serviceable snapshot:
# gluster snapshot activate <snapshot-name>
To disable user serviceable snapshot run the following command:
# gluster volume set VOLNAME features.uss disable
For example:
# gluster volume set test_vol features.uss disable
volume set: success

8.13.2. Viewing and Retrieving Snapshots using NFS / FUSE

For every snapshot available for a volume, any user who has access to the volume will have a read-only view of the volume. You can recover the files through these read-only views of the volume from different point in time. Each snapshot of the volume will be available in the .snaps directory of every directory of the mounted volume.

Note

To access the snapshot you must first mount the volume.
For NFS mount refer Section 6.3.2.2.1, “Manually Mounting Volumes Using Gluster NFS (Deprecated)” for more details. Following command is an example.
# mount -t nfs -o vers=3 server1:/test-vol /mnt/glusterfs
For FUSE mount refer Section 6.2.3.2, “Mounting Volumes Manually” for more details. Following command is an example.
# mount -t glusterfs server1:/test-vol /mnt/glusterfs
The .snaps directory is a virtual directory which will not be listed by either the ls command, or the ls -a option. The .snaps directory will contain every snapshot taken for that given volume as individual directories. Each of these snapshot entries will in turn contain the data of the particular directory the user is accessing from when the snapshot was taken.
To view or retrieve a file from a snapshot follow these steps:
  1. Go to the folder where the file was present when the snapshot was taken. For example, if you had a test.txt file in the root directory of the mount that has to be recovered, then go to that directory.
    # cd /mnt/glusterfs

    Note

    Since every directory has a virtual .snaps directory, you can enter the .snaps directory from here. Since .snaps is a virtual directory, ls and ls -a command will not list the .snaps directory. For example:
    # ls -a
          ....Bob  John  test1.txt  test2.txt
  2. Go to the .snaps folder
    # cd .snaps
  3. Run the ls command to list all the snaps
    For example:
     # ls -p
     snapshot_Dec2014/    snapshot_Nov2014/    snapshot_Oct2014/    snapshot_Sept2014/
  4. Go to the snapshot directory from where the file has to be retrieved.
    For example:
    cd snapshot_Nov2014
    # ls -p
        John/  test1.txt  test2.txt
  5. Copy the file/directory to the desired location.
    # cp -p test2.txt  $HOME

8.13.3. Viewing and Retrieving Snapshots using CIFS for Windows Client

For every snapshot available for a volume, any user who has access to the volume will have a read-only view of the volume. You can recover the files through these read-only views of the volume from different point in time. Each snapshot of the volume will be available in the .snaps folder of every folder in the root of the CIFS share. The .snaps folder is a hidden folder which will be displayed only when the following option is set to ON on the volume using the following command:
# gluster volume set volname features.show-snapshot-directory on
After the option is set to ON, every Windows client can access the .snaps folder by following these steps:
  1. In the Folder options, enable the Show hidden files, folders, and drives option.
  2. Go to the root of the CIFS share to view the .snaps folder.

    Note

    The .snaps folder is accessible only in the root of the CIFS share and not in any sub folders.
  3. The list of snapshots are available in the .snaps folder. You can now access the required file and retrieve it.
You can also access snapshots on Windows using Samba. For more information see, Section 6.4.8, “Accessing Snapshots in Windows”.

8.14. Troubleshooting Snapshots

  • Situation

    Snapshot creation fails.

    Step 1

    Check if the bricks are thinly provisioned by following these steps:

    1. Execute the mount command and check the device name mounted on the brick path. For example:
      # mount
      /dev/mapper/snap_lvgrp-snap_lgvol on /rhgs/brick1 type xfs (rw)
      /dev/mapper/snap_lvgrp1-snap_lgvol1 on /rhgs/brick2 type xfs (rw)
    2. Run the following command to check if the device has a LV pool name.
      lvs device-name
      For example:
      #  lvs -o pool_lv /dev/mapper/snap_lvgrp-snap_lgvol
         Pool
         snap_thnpool
      
      
      
      If the Pool field is empty, then the brick is not thinly provisioned.
    3. Ensure that the brick is thinly provisioned, and retry the snapshot create command.
    Step 2

    Check if the bricks are down by following these steps:

    1. Execute the following command to check the status of the volume:
      # gluster volume status VOLNAME
    2. If any bricks are down, then start the bricks by executing the following command:
      # gluster volume start VOLNAME force
    3. To verify if the bricks are up, execute the following command:
      # gluster volume status VOLNAME
    4. Retry the snapshot create command.
    Step 3

    Check if the node is down by following these steps:

    1. Execute the following command to check the status of the nodes:
      # gluster volume status VOLNAME
    2. If a brick is not listed in the status, then execute the following command:
      # gluster pool list
    3. If the status of the node hosting the missing brick is Disconnected, then power-up the node.
    4. Retry the snapshot create command.
    Step 4

    Check if rebalance is in progress by following these steps:

    1. Execute the following command to check the rebalance status:
      gluster volume rebalance VOLNAME status
    2. If rebalance is in progress, wait for it to finish.
    3. Retry the snapshot create command.
  • Situation

    Snapshot delete fails.

    Step 1

    Check if the server quorum is met by following these steps:

    1. Execute the following command to check the peer status:
      # gluster pool list
    2. If nodes are down, and the cluster is not in quorum, then power up the nodes.
    3. To verify if the cluster is in quorum, execute the following command:
      # gluster pool list
    4. Retry the snapshot delete command.
  • Situation

    Snapshot delete command fails on some node(s) during commit phase, leaving the system inconsistent.

    Solution

    1. Identify the node(s) where the delete command failed. This information is available in the delete command's error output. For example:
      # gluster snapshot delete snapshot1
      Deleting snap will erase all the information about the snap. Do you still want to continue? (y/n) y
      snapshot delete: failed: Commit failed on 10.00.00.02. Please check log file for details.
      Snapshot command failed
    2. On the node where the delete command failed, bring down glusterd using the following command:
      On RHEL 7 and RHEL 8, run
      # systemctl stop glusterd
      On RHEL 6, run
      # service glusterd stop

      Important

      Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
    3. Delete that particular snaps repository in /var/lib/glusterd/snaps/ from that node. For example:
      # rm -rf /var/lib/glusterd/snaps/snapshot1
    4. Start glusterd on that node using the following command:
      On RHEL 7 and RHEL 8, run
      # systemctl start glusterd
      On RHEL 6, run
      # service glusterd start.

      Important

      Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
    5. Repeat the 2nd, 3rd, and 4th steps on all the nodes where the commit failed as identified in the 1st step.
    6. Retry deleting the snapshot. For example:
      # gluster snapshot delete snapshot1
  • Situation

    Snapshot restore fails.

    Step 1

    Check if the server quorum is met by following these steps:

    1. Execute the following command to check the peer status:
      # gluster pool list
    2. If nodes are down, and the cluster is not in quorum, then power up the nodes.
    3. To verify if the cluster is in quorum, execute the following command:
      # gluster pool list
    4. Retry the snapshot restore command.
    Step 2

    Check if the volume is in Stop state by following these steps:

    1. Execute the following command to check the volume info:
      # gluster volume info VOLNAME
    2. If the volume is in Started state, then stop the volume using the following command:
      gluster volume stop VOLNAME
    3. Retry the snapshot restore command.
  • Situation

    Snapshot commands fail.

    Step 1

    Check if there is a mismatch in the operating versions by following these steps:

    1. Open the following file and check for the operating version:
      /var/lib/glusterd/glusterd.info
      If the operating-version is lesser than 30000, then the snapshot commands are not supported in the version the cluster is operating on.
    2. Upgrade all nodes in the cluster to Red Hat Gluster Storage 3.2 or higher.
    3. Retry the snapshot command.
  • Situation

    After rolling upgrade, snapshot feature does not work.

    Solution

    You must ensure to make the following changes on the cluster to enable snapshot:

    1. Restart the volume using the following commands.
      # gluster volume stop VOLNAME
      # gluster volume start VOLNAME
    2. Restart glusterd services on all nodes.
      On RHEL 7 and RHEL 8, run
      # systemctl restart glusterd
      On RHEL 6, run
      # service glusterd restart

      Important

      Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide

Chapter 9. Managing Directory Quotas

Warning

Quota is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support Quota in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
Quotas allow you to set limits on the disk space used by a directory. Storage administrators can control the disk space utilization at the directory and volume levels. This is particularly useful in cloud deployments to facilitate the use of utility billing models.

9.1. Enabling and Disabling Quotas

To limit disk usage, you need to enable quota usage on a volume by running the following command:
# gluster volume quota VOLNAME enable
This command only enables quota behavior on the volume; it does not set any default disk usage limits.

Note

On a gluster volume with quota enabled, the CPU and memory consumption accelarates based on various factors. For example, complexity of the file system tree, number of bricks, nodes in the pool, number of quota limits placed across the filesystem, and the frequency of quota traversals across the filesystem.
To disable quota behavior on a volume, including any set disk usage limits, run the following command:
# gluster volume quota VOLNAME disable

Important

When you disable quotas on Red Hat Gluster Storage 3.1.1 and earlier, all previously configured limits are removed from the volume by a cleanup process, quota-remove-xattr.sh. If you re-enable quotas while the cleanup process is still running, the extended attributes that enable quotas may be removed by the cleanup process. This has negative effects on quota accounting.

9.2. Before Setting a Quota on a Directory

There are several things you should keep in mind when you set a quota on a directory.
  • When specifying a directory to limit with the gluster volume quota command, the directory's path is relative to the Red Hat Gluster Storage volume mount point, not the root directory of the server or client on which the volume is mounted. That is, if the Red Hat Gluster Storage volume is mounted at /mnt/glusterfs and you want to place a limit on the /mnt/glusterfs/dir directory, use /dir as the path when you run the gluster volume quota command, like so:
    # gluster volume quota VOLNAME limit-usage /dir hard_limit
  • Ensure that at least one brick is available per replica set when you run the gluster volume quota command. A brick is available if a Y appears in the Online column of gluster volume status command output, like so:
    # gluster volume status VOLNAME
    Status of volume: VOLNAME
    Gluster process                        Port    Online   Pid
    ------------------------------------------------------------
    Brick arch:/export/rep1                24010   Y       18474
    Brick arch:/export/rep2                24011   Y       18479
    NFS Server on localhost                38467   Y       18486
    Self-heal Daemon on localhost          N/A     Y       18491

9.3. Limiting Disk Usage

9.3.1. Setting Disk Usage Limits

If your system requires that a certain amount of space remains free in order to achieve a certain level of performance, you may need to limit the amount of space that Red Hat Gluster Storage consumes on a volume or directory.
Use the following command to limit the total allowed size of a directory, or the total amount of space to be consumed on a volume.
# gluster volume quota VOLNAME limit-usage path hard_limit
For example, to limit the size of the /dir directory on the data volume to 100 GB, run the following command:
# gluster volume quota data limit-usage /dir 100GB
This prevents the /dir directory and all files and directories underneath it from containing more than 100 GB of data cumulatively.
To limit the size of the entire data volume to 1 TB, set a 1 TB limit on the root directory of the volume, like so:
# gluster volume quota data limit-usage / 1TB
You can also set a percentage of the hard limit as a soft limit. Exceeding the soft limit for a directory logs warnings rather than preventing further disk usage. For example, to set a soft limit at 75% of your volume's hard limit of 1TB, run the following command.
# gluster volume quota data limit-usage / 1TB 75
By default, brick logs are found in /var/log/glusterfs/bricks/BRICKPATH.log.
The default soft limit is 80%. However, you can alter the default soft limit on a per-volume basis by using the default-soft-limit subcommand. For example, to set a default soft limit of 90% on the data volume, run the following command:
# gluster volume quota data default-soft-limit 90
Then verify that the new value is set with the following command:
# gluster volume quota VOLNAME list
Changing the default soft limit does not remove a soft limit set with the limit-usage subcommand.

9.3.2. Viewing Current Disk Usage Limits

You can view all of the limits currently set on a volume by running the following command:
# gluster volume quota VOLNAME list
For example, to view the quota limits set on test-volume:
# gluster volume quota test-volume list
Path        Hard-limit  Soft-limit   Used      Available
--------------------------------------------------------
/           50GB        75%          0Bytes    50.0GB
/dir        10GB        75%          0Bytes    10.0GB
/dir/dir2   20GB        90%          0Bytes    20.0GB
To view limit information for a particular directory, specify the directory path. Remember that the directory's path is relative to the Red Hat Gluster Storage volume mount point, not the root directory of the server or client on which the volume is mounted.
# gluster volume quota VOLNAME list /<directory_name>
For example, to view limits set on the /dir directory of the test-volume volume:
# gluster volume quota test-volume list /dir
Path  Hard-limit   Soft-limit   Used   Available
-------------------------------------------------
/dir   10.0GB          75%       0Bytes  10.0GB
You can also list multiple directories to display disk limit information on each directory specified, like so:
# gluster volume quota VOLNAME list DIR1  DIR2

9.3.2.1. Viewing Quota Limit Information Using the df Utility

By default, the df utility does not take quota limits into account when reporting disk usage. This means that clients accessing directories see the total space available to the volume, rather than the total space allotted to their directory by quotas. You can configure a volume to display the hard quota limit as the total disk space instead by setting quota-deem-statfs parameter to on.
To set the quota-deem-statfs parameter to on, run the following command:
# gluster volume set VOLNAME quota-deem-statfs on
This configures df to to display the hard quota limit as the total disk space for a client.
The following example displays the disk usage as seen from a client when quota-deem-statfs is set to off:
# df -hT /home
Filesystem           Type            Size  Used Avail Use% Mounted on
server1:/test-volume fuse.glusterfs  400G   12G  389G   3% /home
The following example displays the disk usage as seen from a client when quota-deem-statfs is set to on:
# df -hT /home
Filesystem            Type            Size  Used Avail Use% Mounted on
server1:/test-volume  fuse.glusterfs  300G   12G  289G   4% /home

9.3.3. Setting Quota Check Frequency (Timeouts)

You can configure how frequently Red Hat Gluster Storage checks disk usage against the disk usage limit by specifying soft and hard timeouts.
The soft-timeout parameter specifies how often Red Hat Gluster Storage checks space usage when usage has, so far, been below the soft limit set on the directory or volume. The default soft timeout frequency is every 60 seconds.
To specify a different soft timeout, run the following command:
# gluster volume quota VOLNAME soft-timeout seconds
The hard-timeout parameter specifies how often Red Hat Gluster Storage checks space usage when usage is greater than the soft limit set on the directory or volume. The default hard timeout frequency is every 5 seconds.
To specify a different hard timeout, run the following command:
# gluster volume quota VOLNAME hard-timeout seconds

Important

Ensure that you take system and application workload into account when you set soft and hard timeouts, as the margin of error for disk usage is proportional to system workload.

9.3.4. Setting Logging Frequency (Alert Time)

The alert-time parameter configures how frequently usage information is logged after the soft limit has been reached. You can configure alert-time with the following command:
# gluster volume quota VOLNAME alert-time time
By default, alert time is 1 week (1w).
The time parameter in the command can be used with one of the following formats:

Table 9.1. 

Unit of time Format 1 Format 2
Second(s) [integer]s [integer]sec
Minute(s) [integer]m [integer]min
Hour(s) [integer]h [integer]hr
Day(s) [integer]d [integer]days
Week(s) [integer]w [integer]wk
The [integer] is the number of units of time that need to be provided. Any one of the format for any unit of time can be used. For example:
The following command sets the logging frequency for volume named test-vol to every 10 minutes.
# gluster volume quota test-vol alert-time 10m
Whereas, the following command will set the logging frequency for volume named test-vol to every 10 days.
# gluster volume quota test-vol alert-time 10days

9.3.5. Removing Disk Usage Limits

If you don't need to limit disk usage, you can remove the usage limits on a directory by running the following command:
# gluster volume quota VOLNAME remove DIR
For example, to remove the disk limit usage on /data directory of test-volume:
# gluster volume quota test-volume remove /data
  volume quota : success
To remove a volume-wide quota, run the following command:
# gluster vol quota VOLNAME remove /
This does not remove limits recursively; it only impacts a volume-wide limit.

Chapter 10. Managing Geo-replication

This section introduces geo-replication, illustrates the various deployment scenarios, and explains how to configure geo-replication and mirroring.

10.1. About Geo-replication

Geo-replication provides a distributed, continuous, asynchronous, and incremental replication service from one site to another over Local Area Networks (LANs), Wide Area Networks (WANs), and the Internet.
Geo-replication uses a master–slave model, where replication and mirroring occurs between the following partners:
  • Master – the primary Red Hat Gluster Storage volume.
  • Slave – a secondary Red Hat Gluster Storage volume. A slave volume can be a volume on a remote host, such as remote-host::volname.

10.2. Replicated Volumes vs Geo-replication

The following table lists the differences between replicated volumes and geo-replication:
Replicated Volumes Geo-replication
Works between all bricks in a replica set, so that changes are synced in both directions.Works only from the primary (master) volume to the secondary (slave) volume.
Mirrors data across bricks within one trusted storage pool. Mirrors data across geographically distributed trusted storage pools.
Provides high-availability. Provides data back-up for disaster recovery.
Synchronous replication: each and every file operation is applied to all the bricks. Asynchronous replication: checks for changes in files periodically, and syncs them on detecting differences.

10.3. Preparing to Deploy Geo-replication

This section provides an overview of geo-replication deployment scenarios, lists prerequisites, and describes how to setup the environment for geo-replication session.

10.3.1. Exploring Geo-replication Deployment Scenarios

Geo-replication provides an incremental replication service over Local Area Networks (LANs), Wide Area Network (WANs), and the Internet. This section illustrates the most common deployment scenarios for geo-replication, including the following:
  • Geo-replication over LAN
  • Geo-replication over WAN
  • Geo-replication over the Internet
  • Multi-site cascading geo-replication
Geo-replication over LAN
Geo-replication over LAN
Geo-replication over WAN
Geo-replication over WAN
Geo-replication over Internet
Geo-replication over Internet
Multi-site cascading Geo-replication
Multi-site cascading geo-replication

10.3.2. Geo-replication Deployment Overview

Deploying geo-replication involves the following steps:
  1. Verify that your environment matches the minimum system requirements. See Section 10.3.3, “Prerequisites”.
  2. Determine the appropriate deployment scenario. See Section 10.3.1, “Exploring Geo-replication Deployment Scenarios”.
  3. Start geo-replication on the master and slave systems.

10.3.3. Prerequisites

The following are prerequisites for deploying geo-replication:
Note that these prerequisites only need to be carried out once from one cluster to another cluster, so if you are syncing multiple volumes from the same master cluster to the same slave cluster, you need only perform these prerequisites once.
  • The master and slave volumes must use the same version of Red Hat Gluster Storage.
  • Nodes in the slave volume must not be part of the master volume. Two separate trusted storage pools are required.
  • Disable the performance.quick-read option in the slave volume using the following command:
    [slave ~]# gluster volume set slavevol performance.quick-read off
  • Time must be synchronized between all master and slave nodes before geo-replication is configured. Red Hat recommends setting up a network time protocol service to keep time synchronized between bricks and servers, and avoid out-of-time synchronization errors.
    See Network Time Protocol Setup for more information.
  • Add the required port for geo-replication from the ports listed in the Section 3.1.2, “Port Access Requirements”.
  • Key-based SSH authentication without a password is required between one node of the master volume (the node from which the geo-replication create command will be executed), and one node of the slave volume (the node whose IP/hostname will be mentioned in the slave name when running the geo-replication create command).
    Create the public and private keys using ssh-keygen (without passphrase) on the master node:
    # ssh-keygen
    Copy the public key to the slave node using the following command:
    # ssh-copy-id -i identity_file root@slave_node_IPaddress/Hostname
    If you are setting up a non-root geo-replicaton session, then copy the public key to the respective user location.

    Note

    - Key-based SSH authentication without a password is only required from the master node to the slave node; the slave node does not need this level of access.
    - ssh-copy-id command does not work if ssh authorized_keys file is configured in the custom location. You must copy the contents of .ssh/id_rsa.pub file from the Master and paste it to authorized_keys file in the custom location on the Slave node.
    Gsyncd also requires key-based SSH authentication without a password between every node in the master cluster to every node in the slave cluster. The gluster system:: execute gsec_create command creates secret-pem files on all the nodes in the master, and is used to implement the SSH authentication connection. The push-pem option in the geo-replication create command pushes these keys to all slave nodes.
    For more information on the gluster system::execute gsec_create and push-pem commands, see Section 10.3.4.1, “Setting Up your Environment for Geo-replication Session”.

10.3.4. Setting Up your Environment

You can set up your environment for a geo-replication session in the following ways:

10.3.4.1. Setting Up your Environment for Geo-replication Session

Creating Geo-replication Sessions

  1. To create a common pem pub file, run the following command on the master node where the key-based SSH authentication connection is configured:
    # gluster system:: execute gsec_create
    Alternatively, you can create the pem pub file by running the following command on the master node where the key-based SSH authentication connection is configured. This alternate command generates Geo-rep session specific ssh-keys in all the master nodes and collects public keys from all peer nodes. It also provides a detailed view of the command status.
    # gluster-georep-sshkey generate
    
    +--------------+-------------+---------------+
    |     NODE     | NODE STATUS | KEYGEN STATUS |
    +--------------+-------------+---------------+
    |     node1    |          UP |            OK |
    |     node2    |          UP |            OK |
    |     node3    |          UP |            OK |
    |     node4    |          UP |            OK |
    |     node5    |          UP |            OK |
    |  localhost   |          UP |            OK |
    +--------------+-------------+---------------+
    
  2. Create the geo-replication session using the following command. The push-pem option is needed to perform the necessary pem-file setup on the slave nodes.
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL create push-pem [force]
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol create push-pem

    Note

    • There must be key-based SSH authentication access between the node from which this command is run, and the slave host specified in the above command. This command performs the slave verification, which includes checking for a valid slave URL, valid slave volume, and available space on the slave. If the verification fails, you can use the force option which will ignore the failed verification and create a geo-replication session.
    • The slave volume is in read-only mode by default. However, in case of a failover-failback situation, the original master is made read-only by default as the session is from the original slave to the original master.
  3. Enable shared storage for master and slave volumes:
    # gluster volume set all cluster.enable-shared-storage enable
    For more information on shared storage, see Section 11.12, “Setting up Shared Storage Volume”.
  4. Configure the meta-volume for geo-replication:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config use_meta_volume true
    For more information on configuring meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
  5. Start the geo-replication by running the following command on the master node:
    For example,
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start [force]
  6. Verify the status of the created session by running the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status

10.3.4.2. Setting Up your Environment for a Secure Geo-replication Slave

Geo-replication supports access to Red Hat Gluster Storage slaves through SSH using an unprivileged account (user account with non-zero UID). This method is more secure and it reduces the master's capabilities over slave to the minimum. This feature relies on mountbroker, an internal service of glusterd which manages the mounts for unprivileged slave accounts. You must perform additional steps to configure glusterd with the appropriate mountbroker's access control directives. The following example demonstrates this process:
Perform the following steps on all the Slave nodes to setup an auxiliary glusterFS mount for the unprivileged account:
  1. In all the slave nodes, create a new group. For example, geogroup.

    Note

    You must not use multiple groups for the mountbroker setup. You can create multiple user accounts but the group should be same for all the non-root users.
  2. In all the slave nodes, create a unprivileged account. For example, geoaccount. Add geoaccount as a member of geogroup group.
  3. On any one of the Slave nodes, run the following command to set up mountbroker root directory and group.
    # gluster-mountbroker setup <MOUNT ROOT> <GROUP>
    For example,
    # gluster-mountbroker setup /var/mountbroker-root geogroup
  4. On any one of the Slave nodes, run the following commands to add volume and user to the mountbroker service.
    # gluster-mountbroker add <VOLUME> <USER>
    For example,
    # gluster-mountbroker add slavevol geoaccount
  5. Check the status of the setup by running the following command:
    # gluster-mountbroker status
    
         NODE    NODE STATUS                  MOUNT ROOT         GROUP              USERS
    --------------------------------------------------------------------------------------- localhost             UP   /var/mountbroker-root(OK)  geogroup(OK)  geoaccount(slavevol)
        node2             UP   /var/mountbroker-root(OK)  geogroup(OK)  geoaccount(slavevol)
    
    The output displays the mountbroker status for every peer node in the slave cluster.
  6. Restart glusterd service on all the Slave nodes.
    # service glusterd restart
    After you setup an auxiliary glusterFS mount for the unprivileged account on all the Slave nodes, perform the following steps to setup a non-root geo-replication session.:
  7. Setup key-based SSH authentication from one of the master nodes to the user on one of the slave nodes.
    For example, to setup key-based SSH authentication to the user geoaccount.
    # ssh-keygen
    # ssh-copy-id -i identity_file geoaccount@slave_node_IPaddress/Hostname
  8. Create a common pem pub file by running the following command on the master nodes, where the key-based SSH authentication connection is configured to the user on the slave nodes:
    # gluster system:: execute gsec_create
  9. Create a geo-replication relationship between the master and the slave to the user by running the following command on the master node:
    For example,
    # gluster volume geo-replication MASTERVOL geoaccount@SLAVENODE::slavevol create push-pem
    If you have multiple slave volumes and/or multiple accounts, create a geo-replication session with that particular user and volume.
    For example,
    # gluster volume geo-replication MASTERVOL geoaccount2@SLAVENODE::slavevol2 create push-pem
  10. Enable shared storage for master and slave volumes:
    # gluster volume set all cluster.enable-shared-storage enable
    For more information on shared storage, see Section 11.12, “Setting up Shared Storage Volume”.
  11. On the slave node, which is used to create relationship, run /usr/libexec/glusterfs/set_geo_rep_pem_keys.sh as a root with user name, master volume name, and slave volume names as the arguments.
    For example,
    # /usr/libexec/glusterfs/set_geo_rep_pem_keys.sh geoaccount MASTERVOL SLAVEVOL_NAME
  12. Configure the meta-volume for geo-replication:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config use_meta_volume true
    For more information on configuring meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
  13. Start the geo-replication with slave user by running the following command on the master node:
    For example,
    # gluster volume geo-replication MASTERVOL geoaccount@SLAVENODE::slavevol start
  14. Verify the status of geo-replication session by running the following command on the master node:
    # gluster volume geo-replication MASTERVOL geoaccount@SLAVENODE::slavevol status
Deleting a mountbroker geo-replication options after deleting session

After mountbroker geo-replicaton session is deleted, you must remove the volumes per mountbroker user.

Important

You must first stop and delete the geo-replication session before you can delete volumes from the mountbroker. For more information, see Section 10.4.5, “Stopping a Geo-replication Session” and Section 10.4.6, “Deleting a Geo-replication Session”
To remove the volumes per mountbroker user:
# gluster-mountbroker remove [--volume volume] [--user user]
For example,
# gluster-mountbroker remove --volume slavevol --user geoaccount
# gluster-mountbroker remove --user geoaccount
# gluster-mountbroker remove --volume slavevol
If the volume to be removed is the last one for the mountbroker user, the user is also removed.

Important

If you have a secured geo-replication setup, you must ensure to prefix the unprivileged user account to the slave volume in the command. For example, to execute a geo-replication status command, run the following:
# gluster volume geo-replication MASTERVOL geoaccount@SLAVENODE::slavevol status
In this command, geoaccount is the name of the unprivileged user account.

10.3.5. Configuring a Meta-Volume

Meta-volume aka gluster_shared_storage is the gluster volume used for internal purposes. Setting use_meta_volume to true enables geo-replication to use shared volume in order to store lock file(s) which helps in handling worker fail-overs. For effective handling of node fail-overs in Master volume, geo-replication requires this shared storage to be available across all nodes of the cluster. Hence, ensure that a gluster volume named gluster_shared_storage is created in the cluster, and is mounted at /var/run/gluster/shared_storage on all the nodes in the cluster. For more information on setting up shared storage volume, see Section 11.12, “Setting up Shared Storage Volume”.

Note

With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
  • Configure the meta-volume for geo-replication:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config use_meta_volume true

Important

On RHEL 8, ensure the booleans rsync_full_access on and rsync_client on booleans are set to ON to prevent file permission issues during rsync required by geo-replication.

10.4. Starting Geo-replication

This section describes how to and start geo-replication in your storage environment, and verify that it is functioning correctly.

10.4.1. Starting a Geo-replication Session

Important

You must create the geo-replication session before starting geo-replication. For more information, see Section 10.3.4.1, “Setting Up your Environment for Geo-replication Session”.
To start geo-replication, use one of the following commands:
  • To start the geo-replication session between the hosts:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol start
    Starting geo-replication session between Volume1 & storage.backup.com::slave-vol has been successful
    This command will start distributed geo-replication on all the nodes that are part of the master volume. If a node that is part of the master volume is down, the command will still be successful. In a replica pair, the geo-replication session will be active on any of the replica nodes, but remain passive on the others.
    After executing the command, it may take a few minutes for the session to initialize and become stable.

    Note

    If you attempt to create a geo-replication session and the slave already has data, the following error message will be displayed:
    slave-node::slave is not empty. Please delete existing files in slave-node::slave and retry, or use force to continue without deleting the existing files. geo-replication command failed
  • To start the geo-replication session forcefully between the hosts:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start force
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol start force
    Starting geo-replication session between Volume1 & storage.backup.com::slave-vol has been successful
    This command will force start geo-replication sessions on the nodes that are part of the master volume. If it is unable to successfully start the geo-replication session on any node which is online and part of the master volume, the command will still start the geo-replication sessions on as many nodes as it can. This command can also be used to re-start geo-replication sessions on the nodes where the session has died, or has not started.

10.4.2. Verifying a Successful Geo-replication Deployment

You can use the status command to verify the status of geo-replication in your environment:
# gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status
For example:
# gluster volume geo-replication Volume1 storage.backup.com::slave-vol status

10.4.3. Displaying Geo-replication Status Information

The status command can be used to display information about a specific geo-replication master session, master-slave session, or all geo-replication sessions. The status output provides both node and brick level information.
  • To display information about all geo-replication sessions, use the following command:
    # gluster volume geo-replication status [detail]
  • To display information on all geo-replication sessions from a particular master volume, use the following command:
    # gluster volume geo-replication MASTER_VOL status [detail] 
  • To display information of a particular master-slave session, use the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status [detail]

    Important

    There will be a mismatch between the outputs of the df command (including -h and -k) and inode of the master and slave volumes when the data is in full sync. This is due to the extra inode and size consumption by the changelog journaling data, which keeps track of the changes done on the file system on the master volume. Instead of running the df command to verify the status of synchronization, use # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status detail instead.
  • The geo-replication status command output provides the following information:
    • Master Node: Master node and Hostname as listed in the gluster volume info command output
    • Master Vol: Master volume name
    • Master Brick: The path of the brick
    • Slave User: Slave user name
    • Slave: Slave volume name
    • Slave Node: IP address/hostname of the slave node to which master worker is connected to.
    • Status: The status of the geo-replication worker can be one of the following:
      • Initializing: This is the initial phase of the Geo-replication session; it remains in this state for a minute in order to make sure no abnormalities are present.
      • Created: The geo-replication session is created, but not started.
      • Active: The gsync daemon in this node is active and syncing the data.
      • Passive: A replica pair of the active node. The data synchronization is handled by the active node. Hence, this node does not sync any data.
      • Faulty: The geo-replication session has experienced a problem, and the issue needs to be investigated further. For more information, see Section 10.12, “Troubleshooting Geo-replication” section.
      • Stopped: The geo-replication session has stopped, but has not been deleted.
    • Crawl Status: Crawl status can be one of the following:
      • Changelog Crawl: The changelog translator has produced the changelog and that is being consumed by gsyncd daemon to sync data.
      • Hybrid Crawl: The gsyncd daemon is crawling the glusterFS file system and generating pseudo changelog to sync data.
      • History Crawl: The gsyncd daemon consumes the history changelogs produced by the changelog translator to sync data.
    • Last Synced: The last synced time.
    • Entry: The number of pending entry (CREATE, MKDIR, RENAME, UNLINK etc) operations per session.
    • Data: The number of Data operations pending per session.
    • Meta: The number of Meta operations pending per session.
    • Failures: The number of failures. If the failure count is more than zero, view the log files for errors in the Master bricks.
    • Checkpoint Time: Displays the date and time of the checkpoint, if set. Otherwise, it displays as N/A.
    • Checkpoint Completed: Displays the status of the checkpoint.
    • Checkpoint Completion Time: Displays the completion time if Checkpoint is completed. Otherwise, it displays as N/A.

10.4.4. Configuring a Geo-replication Session

To configure a geo-replication session, use the following command:
# gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config [Name] [Value]
For example:
# gluster volume geo-replication Volume1 storage.backup.com::slave-vol config sync_method rsync
For example, to view the list of all option/value pairs:
# gluster volume geo-replication Volume1 storage.backup.com::slave-vol config
To delete a setting for a geo-replication config option, prefix the option with ! (exclamation mark). For example, to reset log-level to the default value:
# gluster volume geo-replication Volume1 storage.backup.com::slave-vol config '!log-level'

Warning

You must ensure to perform these configuration changes when all the peers in cluster are in Connected (online) state. If you change the configuration when any of the peer is down, the geo-replication cluster would be in inconsistent state when the node comes back online.
Configurable Options

The following table provides an overview of the configurable options for a geo-replication setting:

Option Description
gluster_log_file LOGFILE The path to the geo-replication glusterfs log file.
gluster_log_level LOGFILELEVEL The log level for glusterfs processes.
log_file LOGFILE The path to the geo-replication log file.
log_level LOGFILELEVEL The log level for geo-replication.
changelog_log_level LOGFILELEVEL The log level for the changelog. The default log level is set to INFO.
changelog_batch_size SIZEINBYTES The total size for the changelog in a batch. The default size is set to 727040 bytes.
ssh_command COMMAND The SSH command to connect to the remote machine (the default is SSH).
sync_method NAME The command to use for setting synchronizing method for the files. The available options are rsync or tarssh. The default is rsync. The tarssh allows tar over Secure Shell protocol. Use tarssh option to handle workloads of files that have not undergone edits.

Note

On a RHEL 8.3 or above, before configuring the sync_method as_tarssh_, make sure to install _tar_ package.
# yum install tar
volume_id=UID The command to delete the existing master UID for the intermediate/slave node.
timeout SECONDS The timeout period in seconds.
sync_jobs N
The number of sync-jobs represents the maximum number of syncer threads (rsync processes or tar over ssh processes for syncing) inside each worker. The number of workers is always equal to the number of bricks in the Master volume. For example, a distributed-replicated volume of (3 x 2) with sync-jobs configured at 3 results in 9 total sync-jobs (aka threads) across all nodes/servers.
Active and Passive Workers: The number of active workers is based on the volume configuration. In case of a distribute volume, all bricks (workers) will be active and participate in syncing. In case of replicate or dispersed volume, one worker from each replicate/disperse group (subvolume) will be active and participate in syncing. This is to avoid duplicate syncing from other bricks. The remaining workers in each replicate/disperse group (subvolume) will be passive. In case the active worker goes down, one of the passive worker from the same replicate/disperse group will become an active worker.
ignore_deletes If this option is set to true, a file deleted on the master will not trigger a delete operation on the slave. As a result, the slave will remain as a superset of the master and can be used to recover the master in the event of a crash and/or accidental delete. If this option is set to false, which is the default config option for ignore-deletes, a file deleted on the master will trigger a delete operation on the slave.
checkpoint [LABEL|now] Sets a checkpoint with the given option LABEL. If the option is set as now, then the current time will be used as the label.
sync_acls [true | false]Syncs acls to the Slave cluster. By default, this option is enabled.

Note

Geo-replication can sync acls only with rsync as the sync engine and not with tarssh as the sync engine.
sync_xattrs [true | false]Syncs extended attributes to the Slave cluster. By default, this option is enabled.

Note

Geo-replication can sync extended attributes only with rsync as the sync engine and not with tarssh as the sync engine.
log_rsync_performance [true | false]If this option is set to enable, geo-replication starts recording the rsync performance in log files. By default, this option is disabled.
rsync_optionsAdditional options to rsync. For example, you can limit the rsync bandwidth usage "--bwlimit=<value>".
use_meta_volume [true | false]Set this option to enable, to use meta volume in Geo-replication. By default, this option is disabled.

Note

For more information on meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
meta_volume_mnt PATHThe path of the meta volume mount point.
gfid_conflict_resolution [true | false] Auto GFID conflict resolution feature provides an ability to automatically detect and fix the GFID conflicts between master and slave. This configuration option provides an ability to enable or disable this feature. By default, this option is true.
special_sync_mode
Speeds up the recovery of data from slave. Adds capability to geo-replication to ignore the files created before enabling indexing option.
Tunables for failover or failback mechanism:
None: gsyncd behaves as normal.
blind: gsyncd works with xtime pairs to identify candidates for synchronization.
wrapup: same as normal mode but does not assign xtimes to orphaned files.
recover: files are only transferred if they are identified as changed on the slave.

Note

Use this mode after ensuring that the number of files in the slave is equal to that of master. Geo-replication will synchronize only those files which are created after making Slave volume as Master volume.

10.4.4.1. Geo-replication Checkpoints

10.4.4.1.1. About Geo-replication Checkpoints
Geo-replication data synchronization is an asynchronous process, so changes made on the master may take time to be replicated to the slaves. Data replication to a slave may also be interrupted by various issues, such network outages.
Red Hat Gluster Storage provides the ability to set geo-replication checkpoints. By setting a checkpoint, synchronization information is available on whether the data that was on the master at that point in time has been replicated to the slaves.
10.4.4.1.2. Configuring and Viewing Geo-replication Checkpoint Information
  • To set a checkpoint on a geo-replication session, use the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config checkpoint [now|LABEL]
    For example, to set checkpoint between Volume1 and storage.backup.com:/data/remote_dir:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config checkpoint now
    geo-replication config updated successfully
    The label for a checkpoint can be set as the current time using now, or a particular label can be specified, as shown below:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config checkpoint NEW_ACCOUNTS_CREATED
    geo-replication config updated successfully.
  • To display the status of a checkpoint for a geo-replication session, use the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status detail
  • To delete checkpoints for a geo-replication session, use the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config '!checkpoint'
    For example, to delete the checkpoint set between Volume1 and storage.backup.com::slave-vol:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config '!checkpoint'
    geo-replication config updated successfully

10.4.5. Stopping a Geo-replication Session

To stop a geo-replication session for a root user, use one of the following commands:
  • To stop a geo-replication session between the hosts:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol stop
    Stopping geo-replication session between Volume1 & storage.backup.com::slave-vol has been successful

    Note

    The stop command will fail if:
    • any node that is a part of the volume is offline.
    • if it is unable to stop the geo-replication session on any particular node.
    • if the geo-replication session between the master and slave is not active.
  • To stop a geo-replication session forcefully between the hosts:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop force
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol stop force
    Stopping geo-replication session between Volume1 & storage.backup.com::slave-vol has been successful
    Using force will stop the geo-replication session between the master and slave even if any node that is a part of the volume is offline. If it is unable to stop the geo-replication session on any particular node, the command will still stop the geo-replication sessions on as many nodes as it can. Using force will also stop inactive geo-replication sessions.
To stop a geo-replication session for a non-root user, use the following command:
# gluster volume geo-replication MASTER_VOL geoaccount@SLAVE_HOST::SLAVE_VOL stop

10.4.6. Deleting a Geo-replication Session

Important

You must first stop a geo-replication session before it can be deleted. For more information, see Section 10.4.5, “Stopping a Geo-replication Session”.
To delete a geo-replication session for a root user, use the following command:
# gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL delete reset-sync-time
reset-sync-time: The geo-replication delete command retains the information about the last synchronized time. Due to this, if the same geo-replication session is recreated, then the synchronization will continue from the time where it was left before deleting the session. For the geo-replication session to not maintain any details about the deleted session, use the reset-sync-time option with the delete command. Now, when the session is recreated, it starts synchronization from the beginning just like a new session.
For example:
# gluster volume geo-replication Volume1 storage.backup.com::slave-vol delete
geo-replication command executed successfully

Note

The delete command will fail if:
  • any node that is a part of the volume is offline.
  • if it is unable to delete the geo-replication session on any particular node.
  • if the geo-replication session between the master and slave is still active.

Important

The SSH keys will not removed from the master and slave nodes when the geo-replication session is deleted. You can manually remove the pem files which contain the SSH keys from the /var/lib/glusterd/geo-replication/ directory.
To delete a geo-replication session for a non-root user, use the following command:
# gluster volume geo-replication MASTER_VOL  geoaccount@SLAVE_HOST::SLAVE_VOL delete reset-sync-time

10.5. Setting up Geo-replication using gdeploy

This section describes how to use gdeploy to configure geo-replication, control and verify geo-replication sessions in your storage environment. The gdeploy tool automates the following processes related to geo-replication:

10.5.1. Setting up geo-replication as root user using gdeploy

Setting up a geo-replication session as a root user involves:
  1. Creating a common pem pub file
  2. Creating a geo-replication session
  3. Configuring the meta-volume
  4. Starting the geo-replication session
gdeploy helps in automating these tasks by creating a single configuration file. When gdeploy is installed, a sample configuration file is created in the following location:
/usr/share/doc/gdeploy/examples/geo-replication.conf

Procedure 10.1. Setting up geo-replication as root user using gdeploy

Important

Ensure that the prerequisites listed in Section 10.3.3, “Prerequisites” are complete.
  1. Create a copy of the sample gdeploy configuration file present in the following location:
    /usr/share/doc/gdeploy/examples/geo-replication.conf
  2. Add the required details in the geo-replication section of the configuration file using the following template:
    [geo-replication]
    action=create
    mastervol=Master_IP:Master_Volname
    slavevol=Slave_IP:Slave_Volname
    slavenodes=Slave_IP_1,Slave_IP_2 [Add all slave IP addresses. Each address followed by a comma (,)]
    force=yes [yes or no]
    start=yes [yes or no]
  3. After modifying the configuration file, invoke the configuration using the command:
    # gdeploy -c txt.conf
Following is an example of the modifications to the configuration file in order to set up geo-replication as a root user:
[geo-replication]
action=create
mastervol=10.1.1.29:mastervolume
slavevol=10.1.1.25:slavesvolume
slavenodes=10.1.1.28,10.1.1.86
force=yes
start=yes
For more information on other available values, see Section 5.1.7, “Configuration File”

10.5.2. Setting up a secure geo-replication session using gdeploy

Setting up a secure geo-replication session involves:
  1. Creating a new group with a unprivileged account for all slave nodes
  2. Setting up the mountbroker
  3. Creating a common pem pub file
  4. Creating a geo-replication session
  5. Configuring the meta-volume
  6. Starting the geo-replication session
gdeploy helps in automating these tasks by creating a single configuration file. When gdeploy is installed, a sample configuration file is created in the following location:
/usr/share/doc/gdeploy/examples/georep-secure.conf

Procedure 10.2. Setting up a secure geo-replication session using gdeploy

Important

Ensure that the prerequisites listed in Section 10.3.3, “Prerequisites” are complete.
  1. Create a copy of the sample gdeploy configuration file present in the following location:
    /usr/share/doc/gdeploy/examples/georep-secure.conf
  2. Add the required details in the geo-replication section of the configuration file using the following template:
    [geo-replication]
    action=create
    georepuser=User_Name [If the user is not present, gdeploy creates the geo-replication user.]
    mastervol=Master_IP:Master_Volname
    slavevol=Slave_IP:Slave_Volname
    slavenodes=Slave_IP_1,Slave_IP_2 [Add all slave IP addresses. Each address followed by a comma (,)]
    force=yes [yes or no]
    start=yes [yes or no]
  3. After modifying the configuration file, invoke the configuration using the command:
    # gdeploy -c txt.conf
The following is an example of the modifications to the configuration file in order to set up a secure geo-replication session:
[geo-replication]
action=create
georepuser=testgeorep
mastervol=10.1.1.29:mastervolume
slavevol=10.1.1.25:slavesvolume
slavenodes=10.1.1.28,10.1.1.86
force=yes
start=yes
For more information on other available values, see Section 5.1.7, “Configuration File”

10.5.3. Controlling geo-replication sessions using gdeploy

gdeploy version 2.0.2-35 supports controlling geo-replication sessions on Red Hat Gluster Storage 3.5. Using gdeploy, the following actions can be performed for controlling a geo-replication session:
When gdeploy is installed, sample configuration files are created in /usr/share/doc/gdeploy/examples. The sample configuration file names for each action are as follows:

Table 10.1. gdeploy for Geo-replication Configuration File Names

Geo-replication Session Control Configuration File Name
Starting a sessiongeorep-start.conf
Stopping a sessiongeorep-stop.conf
Pausing a sessiongeorep-pause.conf
Resuming a sessiongeorep-resume.conf
Deleting a sessiongeorep-delete.conf

Procedure 10.3. Controlling geo-replication sessions using gdeploy

Important

Ensure that the prerequisites listed in Section 10.3.3, “Prerequisites” are complete.
  1. Create a copy of the required gdeploy sample configuration file present in the following location:
    /usr/share/doc/gdeploy/examples
  2. Add the required information in the geo-replication section of the configuration file using the following template:
    [geo-replication]
    action=Action_Name
    georepuser=User_Name If georepuser variable is omitted, the user is assumed to be root user.
    mastervol=Master_IP:Master_Volname
    slavevol=Slave_IP:Slave_Volname
    slavenodes=Slave_IP_1,Slave_IP_2 [Add all slave IP addresses. Each address followed by a comma (,)]
    force=yes [yes or no]
    start=yes [yes or no]

    Important

    If georepuser variable is omitted, the user is assumed to be root user.
  3. After modifying the configuration file, invoke the configuration using the command:
    # gdeploy -c txt.conf
Following are the examples of the modifications to the configuration file in order to control a geo-replication session:
Starting a geo-replication session

[geo-replication]
action=start
mastervol=10.1.1.29:mastervolume
slavevol=10.1.1.25:slavevolume
Stopping a geo-replication session

[geo-replication]
action=stop
mastervol=10.1.1.29:mastervolume
slavevol=10.1.1.25:slavevolume
force=yes
Pausing a geo-replication session

[geo-replication]
action=pause
mastervol=10.1.1.29:mastervolume
slavevol=10.1.1.25:slavevolume
force=yes
Resuming a geo-replication session

[geo-replication]
action=resume
mastervol=10.1.1.29:mastervolume
slavevol=10.1.1.25:slavevolume
force=yes
Deleting a geo-replication session

[geo-replication]
action=delete
mastervol=10.1.1.29:mastervolume
slavevol=10.1.1.25:slavevolume
force=yes
For more information on available values, see Section 5.1.7, “Configuration File”

10.6. Starting Geo-replication on a Newly Added Brick, Node, or Volume

10.6.1. Starting Geo-replication for a New Brick or New Node

If a geo-replication session is running, and a new node is added to the trusted storage pool or a brick is added to the volume from a newly added node in the trusted storage pool, then you must perform the following steps to start the geo-replication daemon on the new node:
  1. Run the following command on the master node where key-based SSH authentication connection is configured, in order to create a common pem pub file.
    # gluster system:: execute gsec_create
  2. Create the geo-replication session using the following command. The push-pem and force options are required to perform the necessary pem-file setup on the slave nodes.
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL create push-pem force
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol create push-pem force

    Note

    There must be key-based SSH authentication access between the node from which this command is run, and the slave host specified in the above command. This command performs the slave verification, which includes checking for a valid slave URL, valid slave volume, and available space on the slave.
  3. After successfully setting up the shared storage volume, when a new node is added to the cluster, the shared storage is not mounted automatically on this node. Neither is the /etc/fstab entry added for the shared storage on this node. To make use of shared storage on this node, execute the following commands:
    # mount -t glusterfs <local node's ip>:gluster_shared_storage
    /var/run/gluster/shared_storage
    # cp /etc/fstab /var/run/gluster/fstab.tmp
    # echo "<local node's ip>:/gluster_shared_storage
    /var/run/gluster/shared_storage/ glusterfs defaults 0 0" >> /etc/fstab

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
    For more information on setting up shared storage volume, see Section 11.12, “Setting up Shared Storage Volume”.
  4. Configure the meta-volume for geo-replication:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config use_meta_volume true
    For more information on configuring meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
  5. If a node is added at slave, stop the geo-replication session using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop
  6. Start the geo-replication session between the slave and master forcefully, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start force
  7. Verify the status of the created session, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status

    Warning

    The following scenarios can lead to a checksum mismatch:
    • Adding bricks to expand a geo-replicated volume.
    • Expanding the volume while the geo-replication synchronization is in progress.
    • Newly added brick becomes `ACTIVE` to sync the data.
    • Self healing on the new brick is not completed.

10.6.2. Starting Geo-replication for a New Brick on an Existing Node

When adding a brick to the volume on an existing node in the trusted storage pool with a geo-replication session running, the geo-replication daemon on that particular node will automatically be restarted. The new brick will then be recognized by the geo-replication daemon. This is an automated process and no configuration changes are required.

10.6.3. Starting Geo-replication for a New Volume

To create and start a geo-replication session between a new volume added to the master cluster and a new volume added to the slave cluster, you must perform the following steps:

Prerequisites

  • There must be key-based SSH authentication without a password access between the master volume node and the slave volume node.
  1. Create the geo-replication session using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL create
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol create

    Note

    This command performs the slave verification, which includes checking for a valid slave URL, valid slave volume, and available space on the slave.
  2. Configure the meta-volume for geo-replication:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true
    For example:
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol config use_meta_volume true
    For more information on configuring meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
  3. Start the geo-replication session between the slave and master, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start
  4. Verify the status of the created session, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status

10.7. Scheduling Geo-replication as a Cron Job

Cron is a daemon that can be used to schedule the execution of recurring tasks according to a combination of the time, day of the month, month, day of the week, and week. Cron assumes that the system is ON continuously. If the system is not ON when a task is scheduled, it is not executed. A script is provided to run geo-replication only when required or to schedule geo-replication to run during low I/O.
For more information on installing Cron and configuring Cron jobs, see Automating System Tasks in the Red Hat Enterprise Linux 7 System Administrator's Guide.
The script provided to schedule the geo-replication session, performs the following:
  1. Stops the geo-replication session, if started
  2. Starts the geo-replication session
  3. Sets the Checkpoint
  4. Checks the status of checkpoint until it is complete
  5. After the checkpoint is complete, stops the geo-replication session
Run geo-replication Session

To run a geo-reolication session only when required, run the following script:

# python /usr/share/glusterfs/scripts/schedule_georep.py MASTERVOL SLAVEHOST SLAVEVOL
For example,
# python /usr/share/glusterfs/scripts/schedule_georep.py Volume1 storage.backup.com slave-vol
Run the following command to view the help:
# python /usr/share/glusterfs/scripts/schedule_georep.py --help
Schedule a Cron Job

To schedule geo-replication to run automatically using Cron:

minute hour day month day-of-week directory_and_script-to-execute MASTERVOL SLAVEHOST SLAVEVOL >> log_file_for_script_output
For example, to run geo-replication daily at 20:30 hours, run the following:
30 20 * * * root python /usr/share/glusterfs/scripts/schedule_georep.py --no-color Volume1 storage.backup.com slave-vol >> /var/log/glusterfs/schedule_georep.log 2>&1

10.8. Disaster Recovery

Red Hat Gluster Storage provides geo-replication failover and failback capabilities for disaster recovery. If the master goes offline, you can perform a failover procedure so that a slave can replace the master. When this happens, all the I/O operations, including reads and writes, are done on the slave which is now acting as the master. When the original master is back online, you can perform a failback procedure on the original slave so that it synchronizes the differences back to the original master.

10.8.1. Failover: Promoting a Slave to Master

If the master volume goes offline, you can promote a slave volume to be the master, and start using that volume for data access.
  1. Disable read-only on the slave volume by running the following command:
    # gluster volume set VOLNAME features.read-only off
  2. Run the following commands on the slave machine to promote it to be the master:
    # gluster volume set VOLNAME geo-replication.indexing on
    # gluster volume set VOLNAME changelog on
    For example
    # gluster volume set slave-vol geo-replication.indexing on
     volume set: success
    # gluster volume set slave-vol changelog on
     volume set: success
You can now configure applications to use the slave volume for I/O operations.

10.8.2.  Failback: Resuming Master and Slave back to their Original State

When the original master is back online, you can perform the following procedure on the original slave so that it synchronizes the differences back to the original master:
  1. Stop the existing geo-rep session from original master to orginal slave using the following command:
    # gluster volume geo-replication  ORIGINAL_MASTER_VOL ORIGINAL_SLAVE_HOST::ORIGINAL_SLAVE_VOL stop force
    For example,
    # gluster volume geo-replication  Volume1 storage.backup.com::slave-vol stop force
    Stopping geo-replication session between Volume1 and storage.backup.com::slave-vol has been successful
  2. Create a new geo-replication session with the original slave as the new master, and the original master as the new slave with force option. Detailed information on creating geo-replication session is available at: .
  3. Start the special synchronization mode to speed up the recovery of data from slave. This option adds capability to geo-replication to ignore the files created before enabling indexing option. With this option, geo-replication will synchronize only those files which are created after making Slave volume as Master volume.
    # gluster volume geo-replication ORIGINAL_SLAVE_VOL ORIGINAL_MASTER_HOST::ORIGINAL_MASTER_VOL config special-sync-mode recover
    For example,
    # gluster volume geo-replication  slave-vol master.com::Volume1 config special-sync-mode recover
    geo-replication config updated successfully
    
  4. Disable the gfid-conflict-resolution option:
    # gluster volume geo-replication ORIGINAL_SLAVE_VOL ORIGINAL_MASTER_HOST::ORIGINAL_MASTER_VOL config gfid-conflict-resolution false
    For example,
    # gluster volume geo-replication slave-vol master.com::Volume1 config gfid-conflict-resolution false
    geo-replication config updated successfully
    
  5. Start the new geo-replication session using the following command:
    # gluster volume geo-replication ORIGINAL_SLAVE_VOL ORIGINAL_MASTER_HOST::ORIGINAL_MASTER_VOL start
    For example,
    # gluster volume geo-replication slave-vol master.com::Volume1 start
    Starting geo-replication session between slave-vol and master.com::Volume1 has been successful
    
  6. Stop the I/O operations on the original slave and set the checkpoint. By setting a checkpoint, synchronization information is available on whether the data that was on the master at that point in time has been replicated to the slaves.
    # gluster volume geo-replication ORIGINAL_SLAVE_VOL ORIGINAL_MASTER_HOST::ORIGINAL_MASTER_VOL config checkpoint now
    For example,
    # gluster volume geo-replication slave-vol master.com::Volume1 config checkpoint now
    geo-replication config updated successfully
    
  7. Checkpoint completion ensures that the data from the original slave is restored back to the original master. But since the IOs were stopped at slave before checkpoint was set, we need to touch the slave mount for checkpoint to be completed
    # touch orginial_slave_mount 
    # gluster volume geo-replication ORIGINAL_SLAVE_VOL ORIGINAL_MASTER_HOST::ORIGINAL_MASTER_VOL status detail
    For example,
    # touch /mnt/gluster/slavevol
    # gluster volume geo-replication slave-vol master.com::Volume1 status detail
    
  8. After the checkpoint is complete, stop and delete the current geo-replication session between the original slave and original master
    # gluster volume geo-replication ORIGINAL_SLAVE_VOL ORIGINAL_MASTER_HOST::ORIGINAL_MASTER_VOL stop
    # gluster volume geo-replication ORIGINAL_SLAVE_VOL ORIGINAL_MASTER_HOST::ORIGINAL_MASTER_VOL delete
    For example,
    # gluster volume geo-replication slave-vol master.com::Volume1 stop
    Stopping geo-replication session between slave-vol and master.com::Volume1 has been successful
    
    # gluster volume geo-replication slave-vol master.com::Volume1 delete
    geo-replication command executed successfully
    
  9. Disable read-only on the master volume by running the following command:
    # gluster volume set VOLNAME features.read-only off
  10. Reset the options that were set for promoting the slave volume as the master volume by running the following commands:
    # gluster volume reset ORIGINAL_SLAVE_VOL geo-replication.indexing force
    # gluster volume reset ORIGINAL_SLAVE_VOL changelog
    For example,
    # gluster volume reset slave-vol geo-replication.indexing force
    volume set: success
    
    # gluster volume reset slave-vol changelog
    volume set: success
    
  11. Resume the original roles by starting the geo-rep session from the original master using the following command:
    # gluster volume geo-replication ORIGINAL_MASTER_VOL ORIGINAL_SLAVE_HOST::ORIGINAL_SLAVE_VOL start 
    # gluster volume geo-replication Volume1 storage.backup.com::slave-vol start
    Starting geo-replication session between slave-vol  and master.com::Volume1 been successful
    

10.9. Creating a Snapshot of Geo-replicated Volume

The Red Hat Gluster Storage Snapshot feature enables you to create point-in-time copies of Red Hat Gluster Storage volumes, which you can use to protect data. You can create snapshots of Geo-replicated volumes.
For information on prerequisites, creating, and restoring snapshots of geo-replicated volume, see Chapter 8, Managing Snapshots. Creation of a snapshot when geo-replication session is live is not supported and creation of snapshot in this scenario will display the following error:
# gluster snapshot create snap1 master
snapshot create: failed: geo-replication session is running for the volume master. Session needs to be stopped before taking a snapshot.
Snapshot command failed
.
You must ensure to pause the geo-replication session before creating snapshot and resume geo-replication session after creating the snapshot. Information on restoring geo-replicated volume is also available in the Managing Snapshots chapter.

10.10. Example - Setting up Cascading Geo-replication

This section provides step by step instructions to set up a cascading geo-replication session. The configuration of this example has three volumes and the volume names are master-vol, interimmaster-vol, and slave-vol.
  1. Verify that your environment matches the minimum system requirements listed in Section 10.3.3, “Prerequisites”.
  2. Determine the appropriate deployment scenario. For more information on deployment scenarios, see Section 10.3.1, “Exploring Geo-replication Deployment Scenarios”.
  3. Configure the environment and create a geo-replication session between master-vol and interimmaster-vol.
    1. Create a common pem pub file, run the following command on the master node where the key-based SSH authentication connection is configured:
      # gluster system:: execute gsec_create
    2. Create the geo-replication session using the following command. The push-pem option is needed to perform the necessary pem-file setup on the interimmaster nodes.
      # gluster volume geo-replication master-vol interimhost.com::interimmaster-vol create
      push-pem
    3. Verify the status of the created session by running the following command:
      # gluster volume geo-replication master-vol interimhost::interimmaster-vol status
  4. Configure the meta-volume for geo-replication:
    # gluster volume geo-replication master-vol interimhost.com::interimmaster-vol config use_meta_volume true
    For more information on configuring meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
  5. Start a Geo-replication session between the hosts:
    # gluster volume geo-replication master-vol interimhost.com::interimmaster-vol start
    This command will start distributed geo-replication on all the nodes that are part of the master volume. If a node that is part of the master volume is down, the command will still be successful. In a replica pair, the geo-replication session will be active on any of the replica nodes, but remain passive on the others. After executing the command, it may take a few minutes for the session to initialize and become stable.
  6. Verifying the status of geo-replication session by running the following command:
    # gluster volume geo-replication master-vol interimhost.com::interimmaster-vol status
  7. Create a geo-replication session between interimmaster-vol and slave-vol.
    1. Create a common pem pub file by running the following command on the interimmaster master node where the key-based SSH authentication connection is configured:
      # gluster system:: execute gsec_create
    2. On interimmaster node, create the geo-replication session using the following command. The push-pem option is needed to perform the necessary pem-file setup on the slave nodes.
      # gluster volume geo-replication interimmaster-vol slave_host.com::slave-vol create push-pem
    3. Verify the status of the created session by running the following command:
      # gluster volume geo-replication interrimmaster-vol slave_host::slave-vol status
  8. Configure the meta-volume for geo-replication:
    # gluster volume geo-replication interrimmaster-vol slave_host::slave-vol config use_meta_volume true
    For more information on configuring meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
  9. Start a geo-replication session between interrimaster-vol and slave-vol by running the following command:
    # gluster volume geo-replication interrimmaster-vol slave_host.com::slave-vol start
  10. Verify the status of geo-replication session by running the following:
    # gluster volume geo-replication interrimmaster-vol slave_host.com::slave-vol status

10.12. Troubleshooting Geo-replication

This section describes the most common troubleshooting scenarios related to geo-replication.

10.12.1. Tuning Geo-replication performance with Change Log

There are options for the change log that can be configured to give better performance in a geo-replication environment.
The rollover-time option sets the rate at which the change log is consumed. The default rollover time is 15 seconds, but it can be configured to a faster rate. A recommended rollover-time for geo-replication is 10-15 seconds. To change the rollover-time option, use following the command:
# gluster volume set VOLNAME rollover-time 15
The fsync-interval option determines the frequency that updates to the change log are written to disk. The default interval is 5, which means that updates to the change log are written synchronously as they occur, and this may negatively impact performance in a geo-replication environment. Configuring fsync-interval to a non-zero value will write updates to disk asynchronously at the specified interval. To change the fsync-interval option, use following the command:
# gluster volume set VOLNAME fsync-interval 5

10.12.2. Triggering Explicit Sync on Entries

Geo-replication provides an option to explicitly trigger the sync operation of files and directories. A virtual extended attribute glusterfs.geo-rep.trigger-sync is provided to accomplish the same.
# setfattr -n glusterfs.geo-rep.trigger-sync -v "1" <file-path>
The support of explicit trigger of sync is supported only for directories and regular files.

10.12.3. Synchronization Is Not Complete

Situation

The geo-replication status is displayed as Stable, but the data has not been completely synchronized.

Solution

A full synchronization of the data can be performed by erasing the index and restarting geo-replication. After restarting geo-replication, it will begin a synchronization of the data using checksums. This may be a long and resource intensive process on large data sets. If the issue persists, contact Red Hat Support.

For more information about erasing the index, see Section 11.1, “Configuring Volume Options”.

10.12.4. Issues with File Synchronization

Situation

The geo-replication status is displayed as Stable, but only directories and symlinks are synchronized. Error messages similar to the following are in the logs:

[2011-05-02 13:42:13.467644] E [master:288:regjob] GMaster: failed to sync ./some_file`
Solution

Geo-replication requires rsync v3.0.0 or higher on the host and the remote machines. Verify if you have installed the required version of rsync.

10.12.5. Geo-replication Status is Often Faulty

Situation

The geo-replication status is often displayed as Faulty, with a backtrace similar to the following:

012-09-28 14:06:18.378859] E [syncdutils:131:log_raise_exception] <top>: FAIL: Traceback (most recent call last): File "/usr/local/libexec/glusterfs/python/syncdaemon/syncdutils.py", line 152, in twraptf(*aa) File "/usr/local/libexec/glusterfs/python/syncdaemon/repce.py", line 118, in listen rid, exc, res = recv(self.inf) File "/usr/local/libexec/glusterfs/python/syncdaemon/repce.py", line 42, in recv return pickle.load(inf) EOFError
Solution

This usually indicates that RPC communication between the master gsyncd module and slave gsyncd module is broken. Make sure that the following prerequisites are met:

  • Key-based SSH authentication is set up properly between the host and remote machines.
  • FUSE is installed on the machines. The geo-replication module mounts Red Hat Gluster Storage volumes using FUSE to sync data.

10.12.6. Intermediate Master is in a Faulty State

Situation

In a cascading environment, the intermediate master is in a faulty state, and messages similar to the following are in the log:

raise RuntimeError ("aborting on uuid change from %s to %s" % \ RuntimeError: aborting on uuid change from af07e07c-427f-4586-ab9f- 4bf7d299be81 to de6b5040-8f4e-4575-8831-c4f55bd41154
Solution

In a cascading configuration, an intermediate master is loyal to its original primary master. The above log message indicates that the geo-replication module has detected that the primary master has changed. If this change was deliberate, delete the volume-id configuration option in the session that was initiated from the intermediate master.

10.12.7. Remote gsyncd Not Found

Situation

The master is in a faulty state, and messages similar to the following are in the log:

[2012-04-04 03:41:40.324496] E [resource:169:errfail] Popen: ssh> bash: /usr/local/libexec/glusterfs/gsyncd: No such file or directory
Solution

The steps to configure a SSH connection for geo-replication have been updated. Use the steps as described in Section 10.3.4.1, “Setting Up your Environment for Geo-replication Session”

Chapter 11. Managing Red Hat Gluster Storage Volumes

This chapter describes how to perform common volume management operations on the Red Hat Gluster Storage volumes.

11.1. Configuring Volume Options

Note

Volume options can be configured while the trusted storage pool is online.
The current settings for a volume can be viewed using the following command:
# gluster volume info VOLNAME
Volume options can be configured using the following command:
# gluster volume set VOLNAME OPTION PARAMETER
For example, to specify the performance cache size for test-volume:
# gluster volume set test-volume performance.cache-size 256MB
volume set: success
Volume options can be reset using the following command:
# gluster volume reset VOLNAME OPTION_NAME
For example, to reset the changelog option for test-volume:
# gluster volume reset test-volume changelog
volume set: success

11.2. Setting Multiple Volume Option

A group configuration file is a file used to define and customize volume options. There are some predefined group configuration files for specific workload patterns like negative lookup cache, virtualization, metadata cache and gluster-block.
The parameters defined in the file can then be applied to a volume as a group, rather than setting one parameter at a time.

Creating a group configuration file

  1. Create a new file in the /var/lib/glusterd/groups/ directory.
    # touch /var/lib/glusterd/groups/filename
  2. Add the parameters and values that you want to set on the volume to the created file as key-value pairs, placing each parameter on a new line:
    domain1.key1=value1
    domain1.key2=value2
    domain2.key3=value3
    For example,
    changelog.changelog=on
    client.event-threads=6
    cluster.brick-multiplex=on

Adding configurations to volumes

Run the following command to apply the configurations in the group file to specific volumes:
# gluster volume set volname group filename
For example,
# gluster volume set volume1 group virt
# gluster volume set volume2 group virt
# gluster volume set volume3 group dbgroup

Note

The configuration file created should be placed in all the hosts of the trusted storage pool under /var/lib/glusterd/groups/. This can be achieved with the help of gdeploy configuration file.
For information on deactivating group configuration, see Section 21.5, “Deactivating a group configuration”

11.3. Supported Volume Options

The following table lists available volume options along with their description and default value.

Important

The default values are subject to change, and may not be the same for all versions of Red Hat Gluster Storage.

Table 11.1. Volume Options

OptionValue DescriptionAllowed ValuesDefault Value
auth.allowIP addresses or hostnames of the clients which are allowed to access the volume.Valid hostnames or IP addresses, which includes wild card patterns including *. For example, 192.168.1.*. A list of comma separated addresses is acceptable, but a single hostname must not exceed 256 characters.* (allow all)
auth.reject
IP addresses or hostnames of FUSE clients that are denied access to a volume. For NFS access control, use nfs.rpc-auth-* options instead.
Auth.reject takes precedence and overrides auth.allow. If auth.allow and auth.reject contain the same IP address then auth.reject is considered.
Valid hostnames or IP addresses, which includes wild card patterns including *. For example, 192.168.1.*. A list of comma separated addresses is acceptable, but a single hostname must not exceed 256 characters.none (reject none)
changelogEnables the changelog translator to record all the file operations.on | offoff
client.event-threadsSpecifies the number of network connections to be handled simultaneously by the client processes accessing a Red Hat Gluster Storage node.1 - 322
client.strict-locksWith this option enabled, it do not reopen the saved fds after reconnect if POSIX locks are held on them. Hence, subsequent operations on these fds are failed. This is necessary for stricter lock compliance as bricks cleanup any granted locks when a client disconnects.on | offoff

Important

Before enabling client.strict-locks option, upgrade all the servers and clients to RHGS-3.5.5.
cluster.background-self-heal-countThe maximum number of heal operations that can occur simultaneously. Requests in excess of this number are stored in a queue whose length is defined by cluster.heal-wait-queue-leng.0–2568
cluster.brick-multiplex
Available as of Red Hat Gluster Storage 3.3 and later. Controls whether to use brick multiplexing on all volumes. Red Hat recommends restarting volumes after enabling or disabling brick multiplexing. When set to off (the default), each brick has its own process and uses its own port. When set to on, bricks that are compatible with each other use the same process and the same port. This reduces per-brick memory usage and port consumption.
Brick compatibility is determined at volume start, and depends on volume options shared between bricks. When multiplexing is enabled, restart volumes whenever volume configuration is changed in order to maintain the compatibility of the bricks grouped under a single process.
on | offoff
cluster.consistent-metadata
If set to on, the readdirp function in Automatic File Replication feature will always fetch metadata from their respective read children as long as it holds the good copy (the copy that does not need healing) of the file/directory. However, this could cause a reduction in performance where readdirps are involved.
This option requires that the volume is remounted on the client to take effect.
on | offoff
cluster.granular-entry-heal
If set to enable, stores more granular information about the entries which were created or deleted from a directory while a brick in a replica was down. This helps in faster self-heal of directories, especially in use cases where directories with large number of entries are modified by creating or deleting entries. If set to disable, it only stores that the directory needs heal without information about what entries within the directories need to be healed, and thereby requires entire directory crawl to identify the changes.
enable | disableenable

Important

Execute the gluster volume set VOLNAME cluster.granular-entry-heal [enable | disable] command only if the volume is in Created state. If the volume is in any other state other than Created, for example, Started, Stopped, and so on, execute gluster volume heal VOLNAME granular-entry-heal [enable | disable] command to enable or disable granular-entry-heal option.

Important

For new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.4, the cluster.granular-entry-heal option is enabled by default for the replicate volumes.
cluster.heal-wait-queue-lengThe maximum number of requests for heal operations that can be queued when heal operations equal to cluster.background-self-heal-count are already in progress. If more heal requests are made when this queue is full, those heal requests are ignored.0-10000128
cluster.lookup-optimize
If this option is set to on, when a hashed sub-volume does not return a lookup result, negative lookups are optimized by not continuing to look on non-hashed subvolumes.
For existing volumes, any directories created after the upgrade will have lookup-optimize behavior enabled. Rebalance operation has to be performed on all existing directories before they can use the lookup optimization.
For new volumes, the lookup-optimize behavior is enabled by default, except for the root of the volume. Run a rebalance operation in order to enable lookup-optimize for the root of the volume.
on|offon (Red Hat Gluster Storage 3.4 onwards)
cluster.max-bricks-per-process
The maximum number of bricks that can run on a single instance of glusterfsd process.
As of Red Hat Gluster Storage 3.4 Batch 2 Update, the default value of this option is set to 250. This provides better control of resource usage for container-based workloads. In earlier versions, the default value was 0, which used a single process for all bricks on the node.
Updating the value of this option does not affect currently running bricks. Restart the volume to change this setting for existing bricks.
0 to system maximum (any positive integer greater than 1)250
cluster.min-free-diskSpecifies the percentage of disk space that must be kept free. This may be useful for non-uniform bricks.Percentage of required minimum free disk space.10%
cluster.op-versionAllows you to set the operating version of the cluster. The op-version number cannot be downgraded and is set for all volumes in the cluster. The op-version is not listed as part of gluster volume info command output.30708 | 30712 | 31001 | 31101 | 31302 | 31303 | 31304 | 31305 | 31306 | 70200Default value depends on Red Hat Gluster Storage version first installed. For Red Hat Gluster Storage 3.5 the value is set to 70200 for a new deployment.
cluster.read-freq-thresholdSpecifies the number of reads, in a promotion/demotion cycle, that would mark a file HOT for promotion. Any file that has read hits less than this value will be considered as COLD and will be demoted.0-200
cluster.self-heal-daemonSpecifies whether proactive self-healing on replicated volumes is activated.on | offon
cluster.server-quorum-ratioSets the quorum percentage for the trusted storage pool.0 - 100>50%
cluster.server-quorum-typeIf set to server, this option enables the specified volume to participate in the server-side quorum. For more information on configuring the server-side quorum, see Section 11.15.1.1, “Configuring Server-Side Quorum”none | servernone
cluster.quorum-count Specifies the minimum number of bricks that must be available in order for writes to be allowed. This is set on a per-volume basis. This option is used by the cluster.quorum-type option to determine write behavior. Valid values are between 1 and the number of bricks in a replica set.null
cluster.quorum-typeDetermines when the client is allowed to write to a volume. For more information on configuring the client-side quorum, see Section 11.15.1.2, “Configuring Client-Side Quorum” none | fixed | autoauto
cluster.shd-max-threadsSpecifies the number of entries that can be self healed in parallel on each replica by self-heal daemon.1 - 641
cluster.shd-max-threadsSpecifies the number of entries that can be self healed in parallel on each replica by self-heal daemon.1 - 641
cluster.shd-wait-qlengthSpecifies the number of entries that must be kept in the queue for self-heal daemon threads to take up as soon as any of the threads are free to heal. This value should be changed based on how much memory self-heal daemon process can use for keeping the next set of entries that need to be healed.1 - 6555361024
cluster.shd-wait-qlengthSpecifies the number of entries that must be kept in the dispersed subvolume's queue for self-heal daemon threads to take up as soon as any of the threads are free to heal. This value should be changed based on how much memory self-heal daemon process can use for keeping the next set of entries that need to be healed.1 - 6555361024
cluster.tier-demote-frequencySpecifies how frequently the tier daemon must check for files to demote.1 - 172800 seconds3600 seconds
cluster.tier-max-filesSpecifies the maximum number of files that may be migrated in any direction from each node in a given cycle.1-100000 files10000
cluster.tier-max-mbSpecifies the maximum number of MB that may be migrated in any direction from each node in a given cycle.1 -100000 (100 GB)4000 MB
cluster.tier-modeIf set to cache mode, promotes or demotes files based on whether the cache is full or not, as specified with watermarks. If set to test mode, periodically demotes or promotes files automatically based on access.test | cachecache
cluster.tier-promote-frequencySpecifies how frequently the tier daemon must check for files to promote.1- 172800 seconds120 seconds
cluster.use-anonymous-inodeWhen enabled, handles entry heal related issues and heals the directory renames efficiently.on|offon (Red Hat Gluster Storage 3.5.4 onwards)
cluster.use-compound-fopsWhen enabled, write transactions that occur as part of Automatic File Replication are modified so that network round trips are reduced, improving performance.on | offoff
cluster.watermark-hiUpper percentage watermark for promotion. If hot tier fills above this percentage, no promotion will happen and demotion will happen with high probability.1- 99 %90%
cluster.watermark-lowLower percentage watermark. If hot tier is less full than this, promotion will happen and demotion will not happen. If greater than this, promotion/demotion will happen at a probability relative to how full the hot tier is.1- 99 %75%
cluster.write-freq-thresholdSpecifies the number of writes, in a promotion/demotion cycle, that would mark a file HOT for promotion. Any file that has write hits less than this value will be considered as COLD and will be demoted.0-200
config.transportSpecifies the type of transport(s) volume would support communicating over.tcp OR rdma OR tcp,rdmatcp
diagnostics.brick-log-buf-sizeThe maximum number of unique log messages that can be suppressed until the timeout or buffer overflow, whichever occurs first on the bricks.0 and 20 (0 and 20 included)5
diagnostics.brick-log-flush-timeoutThe length of time for which the log messages are buffered, before being flushed to the logging infrastructure (gluster or syslog files) on the bricks.30 - 300 seconds (30 and 300 included)120 seconds
diagnostics.brick-log-formatAllows you to configure the log format to log either with a message id or without one on the brick.no-msg-id | with-msg-idwith-msg-id
diagnostics.brick-log-levelChanges the log-level of the bricks.INFO | DEBUG | WARNING | ERROR | CRITICAL | NONE | TRACEinfo
diagnostics.brick-sys-log-levelDepending on the value defined for this option, log messages at and above the defined level are generated in the syslog and the brick log files.INFO | WARNING | ERROR | CRITICALCRITICAL
diagnostics.client-log-buf-sizeThe maximum number of unique log messages that can be suppressed until the timeout or buffer overflow, whichever occurs first on the clients.0 and 20 (0 and 20 included)5
diagnostics.client-log-flush-timeoutThe length of time for which the log messages are buffered, before being flushed to the logging infrastructure (gluster or syslog files) on the clients.30 - 300 seconds (30 and 300 included)120 seconds
diagnostics.client-log-formatAllows you to configure the log format to log either with a message ID or without one on the client.no-msg-id | with-msg-idwith-msg-id
diagnostics.client-log-levelChanges the log-level of the clients.INFO | DEBUG | WARNING | ERROR | CRITICAL | NONE | TRACEinfo
diagnostics.client-sys-log-levelDepending on the value defined for this option, log messages at and above the defined level are generated in the syslog and the client log files.INFO | WARNING | ERROR | CRITICALCRITICAL
disperse.eager-lockBefore a file operation starts, a lock is placed on the file. The lock remains in place until the file operation is complete. After the file operation completes, if eager-lock is on, the lock remains in place either until lock contention is detected, or for 1 second in order to check if there is another request for that file from the same client. If eager-lock is off, locks release immediately after file operations complete, improving performance for some operations, but reducing access efficiency.on | offon
disperse.other-eager-lockThis option is equivalent to the disperse.eager-lock option but applicable only for non regular files. When multiple clients access a particular directory, disabling disperse.other-eager-lockoption for the volume can improve performance for directory access without compromising performance of I/O's for regular files.on | offon
disperse.other-eager-lock-timeoutMaximum time (in seconds) that a lock on a non regular entry is held if no new operations on the entry are received.0-601
disperse.shd-max-threadsSpecifies the number of entries that can be self healed in parallel on each disperse subvolume by self-heal daemon.1 - 641
disperse.shd-wait-qlengthSpecifies the number of entries that must be kept in the dispersed subvolume's queue for self-heal daemon threads to take up as soon as any of the threads are free to heal. This value should be changed based on how much memory self-heal daemon process can use for keeping the next set of entries that need to be healed.1 - 6555361024
features.ctr_link_consistencyEnables a crash consistent way of recording hardlink updates by Change Time Recorder translator. When recording in a crash consistent way the data operations will experience more latency.on | offoff
features.ctr-enabledEnables Change Time Recorder (CTR) translator for a tiered volume. This option is used in conjunction with features.record-counters option to enable recording write and read heat counters.on | offon
features.locks-notify-contentionWhen this option is enabled and a lock request conflicts with a currently granted lock, an upcall notification will be sent to the current owner of the lock to request it to be released as soon as possible.yes | noyes
features.locks-notify-contention-delayThis value determines the minimum amount of time (in seconds) between upcall contention notifications on the same inode. If multiple lock requests are received during this period, only one upcall will be sent.0-605
features.quota-deem-statfs (Deprecated) When this option is set to on, it takes the quota limits into consideration while estimating the filesystem size. The limit will be treated as the total size instead of the actual size of filesystem.on | offon
features.read-onlySpecifies whether to mount the entire volume as read-only for all the clients accessing it.on | offoff
features.record-countersIf set to enabled, cluster.write-freq-thresholdand cluster.read-freq-thresholdoptions defines the number of writes and reads to a given file that are needed before triggering migration.on | offon
features.shardEnables or disables sharding on the volume. Affects files created after volume configuration.enable | disabledisable
features.shard-block-sizeSpecifies the maximum size of file pieces when sharding is enabled. Affects files created after volume configuration.512MB512MB
geo-replication.indexingEnables the marker translator to track the changes in the volume.on | offoff
network.ping-timeoutThe time the client waits for a response from the server. If a timeout occurs, all resources held by the server on behalf of the client are cleaned up. When the connection is reestablished, all resources need to be reacquired before the client can resume operations on the server. Additionally, locks are acquired and the lock tables are updated. A reconnect is a very expensive operation and must be avoided.42 seconds42 seconds
nfs.aclDisabling nfs.acl will remove support for the NFSACL sideband protocol. This is enabled by default.enable | disableenable
nfs.addr-namelookupSpecifies whether to lookup names for incoming client connections. In some configurations, the name server can take too long to reply to DNS queries, resulting in timeouts of mount requests. This option can be used to disable name lookups during address authentication. Note that disabling name lookups will prevent you from using hostnames in nfs.rpc-auth-*options.on | offoff
nfs.disableSpecifies whether to disable NFS exports of individual volumes.on | offoff
nfs.enable-ino32 For nfs clients or applciatons that do not support 64-bit inode numbers, use this option to make NFS return 32-bit inode numbers instead. Disabled by default, so NFS returns 64-bit inode numbers. This value is global and applies to all the volumes in the trusted storage pool. enable | disabledisable
nfs.export-volumesEnables or disables exporting entire volumes. If this option is disabled and the nfs.export-diroption is enabled, you can set subdirectories as the only exports.on | offon
nfs.mount-rmtabPath to the cache file that contains a list of NFS-clients and the volumes they have mounted. Change the location of this file to a mounted (with glusterfs-fuse, on all storage servers) volume to gain a trusted pool wide view of all NFS-clients that use the volumes. The contents of this file provide the information that can get obtained with the showmount command.Path to a directory/var/lib/glusterd/nfs/rmtab
nfs.mount-udpEnable UDP transport for the MOUNT sideband protocol. By default, UDP is not enabled, and MOUNT can only be used over TCP. Some NFS-clients (certain Solaris, HP-UX and others) do not support MOUNT over TCP and enabling nfs.mount-udpmakes it possible to use NFS exports provided by Red Hat Gluster Storage.disable | enabledisable
nfs.nlmBy default, the Network Lock Manager (NLMv4) is enabled. Use this option to disable NLM. Red Hat does not recommend disabling this option.on|offon
nfs.portAssociates glusterFS NFS with a non-default port.1025-6099938465- 38467
nfs.ports-insecureAllows client connections from unprivileged ports. By default only privileged ports are allowed. This is a global setting for allowing insecure ports for all exports using a single option.on | offoff
nfs.rdirplusThe default value is on. When this option is turned off, NFS falls back to standard readdir instead of readdirp. Turning this off would result in more lookup and stat requests being sent from the client which may impact performance.on|offon
nfs.rpc-auth-allow IP_ADRESSESA comma separated list of IP addresses allowed to connect to the server. By default, all clients are allowed.Comma separated list of IP addressesaccept all
nfs.rpc-auth-reject IP_ADRESSESA comma separated list of addresses not allowed to connect to the server. By default, all connections are allowed.Comma separated list of IP addressesreject none
nfs.server-aux-gidsWhen enabled, the NFS-server will resolve the groups of the user accessing the volume. NFSv3 is restricted by the RPC protocol (AUTH_UNIX/AUTH_SYS header) to 16 groups. By resolving the groups on the NFS-server, this limits can get by-passed.on|offoff
nfs.transport-typeSpecifies the transport used by GlusterFS NFS server to communicate with bricks.tcp OR rdmatcp
open-behindIt improves the application's ability to read data from a file by sending success notifications to the application whenever it receives an open call.on | offon
performance.cache-max-file-sizeSets the maximum file size cached by the io-cache translator. Can be specified using the normal size descriptors of KB, MB, GB, TB, or PB (for example, 6 GB).Size in bytes, or specified using size descriptors.2 ^ 64-1 bytes
performance.cache-min-file-sizeSets the minimum file size cached by the io-cache translator. Can be specified using the normal size descriptors of KB, MB, GB, TB, or PB (for example, 6 GB).Size in bytes, or specified using size descriptors.0
performance.cache-refresh-timeoutThe number of seconds cached data for a file will be retained. After this timeout, data re-validation will be performed.0 - 61 seconds1 second
performance.cache-sizeSize of the read cache.Size in bytes, or specified using size descriptors.32 MB
performance.client-io-threadsImproves performance for parallel I/O from a single mount point for dispersed (erasure-coded) volumes by allowing up to 16 threads to be used in parallel. When enabled, 1 thread is used by default, and further threads up to the maximum of 16 are created as required by client workload. This is useful for dispersed and distributed dispersed volumes. This feature is not recommended for distributed, replicated or distributed-replicated volumes. It is disabled by default on replicated and distributed-replicated volume types.on | offon, except for replicated and distributed-replicated volumes
performance.flush-behindSpecifies whether the write-behind translator performs flush operations in the background by returning (false) success to the application before flush file operations are sent to the backend file system.on | offon
performance.io-thread-countThe number of threads in the I/O threads translator.1 - 6416
performance.lazy-openThis option requires open-behind to be on. Perform an open in the backend only when a necessary file operation arrives (for example, write on the file descriptor, unlink of the file). When this option is disabled, perform backend open immediately after an unwinding open.Yes/NoYes
performance.md-cache-timeoutThe time period in seconds which controls when metadata cache has to be refreshed. If the age of cache is greater than this time-period, it is refreshed. Every time cache is refreshed, its age is reset to 0.0-600 seconds1 second
performance.nfs-strict-write-orderingSpecifies whether to prevent later writes from overtaking earlier writes for NFS, even if the writes do not relate to the same files or locations.on | offoff
performance.nfs.flush-behindSpecifies whether the write-behind translator performs flush operations in the background for NFS by returning (false) success to the application before flush file operations are sent to the backend file system.on | offon
performance.nfs.strict-o-directSpecifies whether to attempt to minimize the cache effects of I/O for a file on NFS. When this option is enabled and a file descriptor is opened using the O_DIRECT flag, write-back caching is disabled for writes that affect that file descriptor. When this option is disabled, O_DIRECT has no effect on caching. This option is ignored if performance.write-behind is disabled.on | offoff
performance.nfs.write-behind-trickling-writesEnables and disables trickling-write strategy for the write-behind translator for NFS clients.on | offon
performance.nfs.write-behind-window-sizeSpecifies the size of the write-behind buffer for a single file or inode for NFS.512 KB - 1 GB1 MB
performance.quick-readTo enable/disable quick-read translator in the volume.on | offon
performance.rda-cache-limitThe value specified for this option is the maximum size of cache consumed by the readdir-ahead translator. This value is global and the total memory consumption by readdir-ahead is capped by this value, irrespective of the number/size of directories cached.0-1GB10MB
performance.rda-request-sizeThe value specified for this option will be the size of buffer holding directory entries in readdirp response.4KB-128KB128KB
performance.resync-failed-syncs-after-fsyncIf syncing cached writes that were issued before an fsync operation fails, this option configures whether to reattempt the failed sync operations.on | offoff
performance.strict-o-directSpecifies whether to attempt to minimize the cache effects of I/O for a file. When this option is enabled and a file descriptor is opened using the O_DIRECT flag, write-back caching is disabled for writes that affect that file descriptor. When this option is disabled, O_DIRECT has no effect on caching. This option is ignored if performance.write-behind is disabled.on | offoff
performance.strict-write-orderingSpecifies whether to prevent later writes from overtaking earlier writes, even if the writes do not relate to the same files or locations.on | offoff
performance.use-anonymous-fdThis option requires open-behind to be on. For read operations, use anonymous file descriptor when the original file descriptor is open-behind and not yet opened in the backend.Yes | NoYes
performance.write-behindEnables and disables write-behind translator.on | offon
performance.write-behind-trickling-writesEnables and disables trickling-write strategy for the write-behind translator for FUSE clients.on | offon
performance.write-behind-window-sizeSpecifies the size of the write-behind buffer for a single file or inode.512 KB - 1 GB1 MB
rebal-throttleRebalance process is made multithreaded to handle multiple files migration for enhancing the performance. During multiple file migration, there can be a severe impact on storage system performance. The throttling mechanism is provided to manage it.lazy, normal, aggressivenormal
server.allow-insecureAllows FUSE-based client connections from unprivileged ports. By default, this is enabled, meaning that ports can accept and reject messages from insecure ports. When disabled, only privileged ports are allowed. This is a global setting for allowing insecure ports to be enabled for all FUSE-based exports using a single option. Use nfs.rpc-auth-* options for NFS access control.on | offon
server.anongidValue of the GID used for the anonymous user when root-squash is enabled. When root-squash is enabled, all the requests received from the root GID (that is 0) are changed to have the GID of the anonymous user.0 - 429496729565534 (this UID is also known as nfsnobody)
server.anonuidValue of the UID used for the anonymous user when root-squash is enabled. When root-squash is enabled, all the requests received from the root UID (that is 0) are changed to have the UID of the anonymous user.0 - 429496729565534 (this UID is also known as nfsnobody)
server.event-threadsSpecifies the number of network connections to be handled simultaneously by the server processes hosting a Red Hat Gluster Storage node.1 - 321
server.gid-timeoutThe time period in seconds which controls when cached groups has to expire. This is the cache that contains the groups (GIDs) where a specified user (UID) belongs to. This option is used only when server.manage-gids is enabled.0-4294967295 seconds2 seconds
server.manage-gidsResolve groups on the server-side. By enabling this option, the groups (GIDs) a user (UID) belongs to gets resolved on the server, instead of using the groups that were send in the RPC Call by the client. This option makes it possible to apply permission checks for users that belong to bigger group lists than the protocol supports (approximately 93).on|offoff
server.root-squashPrevents root users from having root privileges, and instead assigns them the privileges of nfsnobody. This squashes the power of the root users, preventing unauthorized modification of files on the Red Hat Gluster Storage servers. This option is used only for glusterFS NFS protocol.on | offoff
server.statedump-pathSpecifies the directory in which the statedumpfiles must be stored./var/run/gluster (for a default installation)Path to a directory
ssl.crl-pathSpecifies the path to a directory containing SSL certificate revocation list (CRL). This list helps the server nodes to stop the nodes with revoked certificates from accessing the cluster.Absolute path of the directory hosting the CRL files.null (No default value. Hence, it is blank until the volume option is set.)
storage.fips-mode-rchecksumIf enabled, posix_rchecksum uses the FIPS compliant SHA256 checksum, else it uses MD5.on | offon

Warning

Do not enable the storage.fips-mode-rchecksum option on volumes with clients that use Red Hat Gluster Storage 3.4 or earlier.
storage.create-maskMaximum set (upper limit) of permission for the files that will be created.0000 - 07770777
storage. create-directory-maskMaximum set (upper limit) of permission for the directories that will be created.0000 - 07770777
storage.force-create-modeMinimum set (lower limit) of permission for the files that will be created.0000 - 07770000
storage.force-directory-modeMinimum set (lower limit) of permission for the directories that will be created.0000 - 07770000

Important

Behavior is undefined in terms of calculated file access mode when both a mask and a matching forced mode are set simultaneously, create-directory-mask and force-directory-mode or create-mask and force-create-mode.
storage.health-check-intervalSets the time interval in seconds for a filesystem health check. You can set it to 0 to disable. The POSIX translator on the bricks performs a periodic health check. If this check fails, the file system exported by the brick is not usable anymore and the brick process (glusterfsd) logs a warning and exits.0-4294967295 seconds30 seconds
storage.health-check-timeoutSets the time interval in seconds to wait for aio_write to finish for health check. Set to 0 to disable.0-4294967295 seconds20 seconds
storage.owner-gidSets the GID for the bricks of the volume. This option may be required when some of the applications need the brick to have a specific GID to function correctly. Example: For QEMU integration the UID/GID must be qemu:qemu, that is, 107:107 (107 is the UID and GID of qemu).Any integer greater than or equal to -1.The GID of the bricks are not changed. This is denoted by -1.
storage.owner-uidSets the UID for the bricks of the volume. This option may be required when some of the applications need the brick to have a specific UID to function correctly. Example: For QEMU integration the UID/GID must be qemu:qemu, that is, 107:107 (107 is the UID and GID of qemu).Any integer greater than or equal to -1.The UID of the bricks are not changed. This is denoted by -1.
storage.reserve
The POSIX translator includes an option that allow users to reserve disk space on the bricks. This option ensures that enough space is retained to allow users to expand disks or cluster when the bricks are nearly full. The option does this by preventing new file creation when the disk has the storage.reserve percentage/size or less free space.
Storage.reserve accepts value either in form of percentage or in form of MB/GB. To reconfigure this volume option from MB/GB to percentage or percentage to MB/GB, make use of the same volume option. Also, the newest set value is considered.
If set to 0 storage.reserve is disabled
0-100% (applicable if parameter is percentage)
or
nKB/MB/GB (applicable when size is used as parameter), where 'n' is the positive integer that needs to be reserved.
Respective examples:
gluster volume set <vol-name> storage.reserve 15%
or
gluster volume set <vol-name> storage.reserve 100GB
1% (1% of the brick size)

Note

Be mindful of the brick size while setting the storage.reserve option in MB/GB. For example, in a case where the value for the volume option is >= brick size, the entire brick will be reserved.
The option works at sub-volume level.
transport.listen-backlogThe maximum number of established TCP socket requests queued and waiting to be accepted at any one time.0 to system maximum1024

11.4. Configuring a volume to be mounted read-only

Volumes can be mounted with read-only permissions at either the mount point or the volume level.
To specify that a volume can only be mounted read-only, enable the read-only volume option by running the following on any Red Hat Gluster Storage server that hosts that volume.
# gluster volume set volname read-only enable

11.5. Configuring Transport Types for a Volume

A volume can support one or more transport types for communication between clients and brick processes. There are three types of supported transport, which are, tcp, rdma, and tcp,rdma.
To change the supported transport types of a volume, follow the procedure:
  1. Unmount the volume on all the clients using the following command:
    # umount mount-point
  2. Stop the volumes using the following command:
    # gluster volume stop volname
  3. Warning

    Using RDMA as a transport protocol is considered deprecated in Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support it on new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
    Change the transport type. For example, to enable both tcp and rdma execute the followimg command:
    # gluster volume set volname config.transport tcp,rdma OR tcp OR rdma
  4. Mount the volume on all the clients. For example, to mount using rdma transport, use the following command:
    # mount -t glusterfs -o transport=rdma server1:/test-volume /mnt/glusterfs

11.6. Reserving Storage on a Volume

The POSIX translator is now enhanced with an option that allows user to reserve disk space on the bricks. Some administrative operations, like expanding storage or rebalancing data across nodes, require spare working space on the disk. The storage.reserve option lets users expand disk or cluster when backend bricks are full.
When the bricks have free space less than or equal to the reserved space, as declared by the user, new files are not created. This prevents ENOSPC errors on mount points.
To enable reserve option, execute the following command:
# gluster volume set volname storage.reserve percentage
Once this option is enabled, the reserved disk space is not used by the mount points. The storage.reserve option either takes a percentage(%) suffixed value or an unsigned integer value suffixed with absolute units(KB, MB, GB etc). The default value for the option is 1%(1% of the brick size). If set to 0 this option is disabled.

Note

When the disk space reduces to the size of reserved disk space, only internal operations like rebalance, self-heal and so on can be performed.

11.7. Expanding Volumes

Warning

Do not perform this process if geo-replication is configured. There is a race condition tracked by Bug 1683893 that means data can be lost when converting a volume if geo-replication is enabled.
Volumes can be expanded while the trusted storage pool is online and available. For example, you can add a brick to a distributed volume, which increases distribution and adds capacity to the Red Hat Gluster Storage volume. Similarly, you can add a group of bricks to a replicated or distributed replicated volume, which increases the capacity of the Red Hat Gluster Storage volume.
When expanding replicated or distributed replicated volumes, the number of bricks being added must be a multiple of the replica count. This also applies to arbitrated volumes. For example, to expand a distributed replicated volume with a replica count of 3, you need to add bricks in multiples of 3 (such as 6, 9, 12, etc.).
You can also convert a replica 2 volume into an arbitrated replica 3 volume by following the instructions in Section 5.7.5, “Converting to an arbitrated volume”.

Important

Converting an existing distribute volume to replicate or distribute-replicate volume is not supported.

Expanding a Volume

  1. From any server in the trusted storage pool, use the following command to probe the server on which you want to add a new brick:
    # gluster peer probe HOSTNAME
    For example:
    # gluster peer probe server5
    Probe successful
    
    # gluster peer probe server6
    Probe successful
  2. Add the bricks using the following command:
    # gluster volume add-brick VOLNAME NEW_BRICK
    For example:
    # gluster volume add-brick test-volume server5:/rhgs/brick5/ server6:/rhgs/brick6/
    Add Brick successful
  3. Check the volume information using the following command:
    # gluster volume info
    The command output displays information similar to the following:
    Volume Name: test-volume
    Type: Distribute-Replicate
    Status: Started
    Number of Bricks: 6
    Bricks:
    Brick1: server1:/rhgs/brick1
    Brick2: server2:/rhgs/brick2
    Brick3: server3:/rhgs/brick3
    Brick4: server4:/rhgs/brick4
    Brick5: server5:/rhgs/brick5
    Brick6: server6:/rhgs/brick6
  4. Rebalance the volume to ensure that files will be distributed to the new brick. Use the rebalance command as described in Section 11.11, “Rebalancing Volumes”.
    The add-brick command should be followed by a rebalance operation to ensure better utilization of the added bricks.

11.7.1. Expanding a Tiered Volume

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
You can add a group of bricks to a cold tier volume and to the hot tier volume to increase the capacity of the Red Hat Gluster Storage volume.

11.7.1.1. Expanding a Cold Tier Volume

Expanding a cold tier volume is same as a non-tiered volume. If you are reusing the brick, ensure to perform the steps listed in “Section 5.3.3, “ Reusing a Brick from a Deleted Volume ”” section.
  1. Detach the tier by performing the steps listed in Section 16.7, “Detaching a Tier from a Volume (Deprecated)”
  2. From any server in the trusted storage pool, use the following command to probe the server on which you want to add a new brick :
    # gluster peer probe HOSTNAME
    For example:
    # gluster peer probe server5
    Probe successful
    
    # gluster peer probe server6
    Probe successful
  3. Add the bricks using the following command:
    # gluster volume add-brick VOLNAME NEW_BRICK
    For example:
    # gluster volume add-brick test-volume server5:/rhgs/brick5/ server6:/rhgs/brick6/
  4. Rebalance the volume to ensure that files will be distributed to the new brick. Use the rebalance command as described in Section 11.11, “Rebalancing Volumes”.
    The add-brick command should be followed by a rebalance operation to ensure better utilization of the added bricks.
  5. Reattach the tier to the volume with both old and new (expanded) bricks:
    # gluster volume tier VOLNAME attach [replica COUNT] NEW-BRICK...

    Important

    When you reattach a tier, an internal process called fix-layout commences internally to prepare the hot tier for use. This process takes time and there will a delay in starting the tiering activities.
    If you are reusing the brick, be sure to clearly wipe the existing data before attaching it to the tiered volume.

11.7.1.2. Expanding a Hot Tier Volume

You can expand a hot tier volume by attaching and adding bricks for the hot tier.
  1. Detach the tier by performing the steps listed in Section 16.7, “Detaching a Tier from a Volume (Deprecated)”
  2. Reattach the tier to the volume with both old and new (expanded) bricks:
    # gluster volume tier VOLNAME attach [replica COUNT] NEW-BRICK...
    For example,
    # gluster volume tier test-volume attach replica 3 server1:/rhgs/tier5 server2:/rhgs/tier6 server1:/rhgs/tier7 server2:/rhgs/tier8

    Important

    When you reattach a tier, an internal process called fix-layout commences internally to prepare the hot tier for use. This process takes time and there will a delay in starting the tiering activities.
    If you are reusing the brick, be sure to clearly wipe the existing data before attaching it to the tiered volume.

11.7.2. Expanding a Dispersed or Distributed-dispersed Volume

Expansion of a dispersed or distributed-dispersed volume can be done by adding new bricks. The number of additional bricks should be in multiple of basic configuration of the volume. For example, if you have a volume with configuration (4+2 = 6), then you must only add 6 (4+2) or multiple of 6 bricks (such as 12, 18, 24 and so on).

Note

If you add bricks to a Dispersed volume, it will be converted to a Distributed-Dispersed volume, and the existing dispersed volume will be treated as dispersed subvolume.
  1. From any server in the trusted storage pool, use the following command to probe the server on which you want to add new bricks:
    # gluster peer probe HOSTNAME
    For example:
    # gluster peer probe server4
    Probe successful
    # gluster peer probe server5
    Probe successful
    # gluster peer probe server6
    Probe successful
  2. Add the bricks using the following command:
    # gluster volume add-brick VOLNAME NEW_BRICK
    For example:
    # gluster volume add-brick test-volume server4:/rhgs/brick7 server4:/rhgs/brick8 server5:/rhgs/brick9 server5:/rhgs/brick10 server6:/rhgs/brick11 server6:/rhgs/brick12
  3. (Optional) View the volume information after adding the bricks:
    # gluster volume info VOLNAME
    For example:
    # gluster volume info test-volume
    Volume Name: test-volume
    Type: Distributed-Disperse
    Volume ID: 2be607f2-f961-4c4b-aa26-51dcb48b97df
    Status: Started
    Snapshot Count: 0
    Number of Bricks: 2 x (4 + 2) = 12
    Transport-type: tcp
    Bricks:
    Brick1: server1:/rhgs/brick1
    Brick2: server1:/rhgs/brick2
    Brick3: server2:/rhgs/brick3
    Brick4: server2:/rhgs/brick4
    Brick5: server3:/rhgs/brick5
    Brick6: server3:/rhgs/brick6
    Brick7: server4:/rhgs/brick7
    Brick8: server4:/rhgs/brick8
    Brick9: server5:/rhgs/brick9
    Brick10: server5:/rhgs/brick10
    Brick11: server6:/rhgs/brick11
    Brick12: server6:/rhgs/brick12
    Options Reconfigured:
    transport.address-family: inet
    performance.readdir-ahead: on
    nfs.disable: on
    
  4. Rebalance the volume to ensure that the files will be distributed to the new brick. Use the rebalance command as described in Section 11.11, “Rebalancing Volumes”.
    The add-brick command should be followed by a rebalance operation to ensure better utilization of the added bricks.

11.7.3. Expanding Underlying Logical Volume

You can expand the size of a logical volume using the lvextend command.
Red Hat recommends following this process when you want to increase the storage capacity of replicated, arbitrated-replicated, or dispersed volumes, but not expanding distributed-replicated, arbitrated-distributed-replicated, or distributed-dispersed volumes.

Warning

It is recommended to involve the Red Hat Support team while performing this operation.
In the case of online logical volume extent, ensure the associated brick process is killed manually. It might occur certain operations are consuming data, or reading or writing a file on an associated brick. Proceeding with the extension before killing the brick process can have an adverse effect on performance. Identify the brick process ID and kill the same using the following command:
# gluster volume status
# kill -9 brick-process-id
  1. Stop all volumes using the brick with the following command:
    # gluster volume stop VOLNAME
  2. Check if new disk is visible using lsblk command:
    # lsblk
  3. Create new physical volume using following command:
    # pvcreate /dev/PHYSICAL_VOLUME_NAME
  4. Use the following command to verify if the physical volume is created:
    # pvs
  5. Extend the existing volume group:
    # vgextend VOLUME_GROUP_NAME /dev/PHYSICAL_VOLUME_NAME
  6. Use the following commands to check the size of volume group, and verify if it reflects the new addition:
    # vgscan
  7. Ensure the volume group created has enough space to extend the logical volume:
    vgdisplay VOLUME_GROUP_NAME
    Retrieve the file system name using the following command:
    # df -h
  8. Extend the logical volume using the following command:
    # lvextend -L+nG /dev/mapper/ LOGICAL_VOLUME_NAME-VOLUME_GROUP_NAME
    In case of thin pool, extend the pool using the following command:
    # lvextend -L+nG VOLUME_GROUP_NAME/POOL_NAME
    In the above commands, n is the additional size in GB to be extended.
    Execute the #lvdisplay command to fetch the pool name.
    Use the following command to check if the logical volume is extended:
    # lvdisplay VOLUME_GROUP_NAME
  9. Execute the following command to expand the filesystem to accommodate the extended logical volume:
    # xfs_growfs /dev/VOLUME_GROUP_NAME/LOGICAL_VOLUME_NAME
  10. Remount the file system using the following command:
    # mount -o remount /dev/VOLUME_GROUP_NAME/LOGICAL_VOLUME_NAME /bricks/path_to_brick
  11. Start all the volumes with force option:
    # gluster volume start VOLNAME force

11.8. Shrinking Volumes

You can shrink volumes while the trusted storage pool is online and available. For example, you may need to remove a brick that has become inaccessible in a distributed volume because of a hardware or network failure.
When shrinking distributed replicated volumes, the number of bricks being removed must be a multiple of the replica count. For example, to shrink a distributed replicated volume with a replica count of 3, you need to remove bricks in multiples of 3 (such as 6, 9, 12, etc.). In addition, the bricks you are removing must be from the same sub-volume (the same replica set). In a non-replicated volume, all bricks must be available in order to migrate data and perform the remove brick operation. In a replicated or arbitrated volume, at least one of the data bricks in the replica set must be available.
The guidelines are identical when removing a distribution set from a distributed replicated volume with arbiter bricks. If you want to reduce the replica count of an arbitrated distributed replicated volume to replica 3, you must remove only the arbiter bricks. If you want to reduce a volume from arbitrated distributed replicated to distributed only, remove the arbiter brick and one replica brick from each replica subvolume.

Shrinking a Volume

  1. Remove a brick using the following command:
    # gluster volume remove-brick VOLNAME BRICK start
    For example:
    # gluster volume remove-brick test-volume server2:/rhgs/brick2 start
              Remove Brick start successful

    Note

    If the remove-brick command is run with force or without any option, the data on the brick that you are removing will no longer be accessible at the glusterFS mount point. When using the start option, the data is migrated to other bricks, and on a successful commit the removed brick's information is deleted from the volume configuration. Data can still be accessed directly on the brick.
  2. You can view the status of the remove brick operation using the following command:
    # gluster volume remove-brick VOLNAME BRICK status
    For example:
    # gluster volume remove-brick test-volume server2:/rhgs/brick2 status
          Node Rebalanced  size scanned failures skipped   status  run time
    	         -files					                                     in h:m:s
    ----------  --------- ------ ------ -------- ------  --------- --------
    localhost        5032 43.4MB  27715       0    5604  completed  0:15:05
    10.70.43.41         0 0Bytes      0       0       0  completed  0:08:18
    
    volume rebalance: test-volume: success
  3. When the data migration shown in the previous status command is complete, run the following command to commit the brick removal:
    # gluster volume remove-brick VOLNAME BRICK commit
    For example,
    # gluster volume remove-brick test-volume server2:/rhgs/brick2 commit
  4. After the brick removal, you can check the volume information using the following command:
    # gluster volume info 
    The command displays information similar to the following:
    # gluster volume info
    Volume Name: test-volume
    Type: Distribute
    Status: Started
    Number of Bricks: 3
    Bricks:
    Brick1: server1:/rhgs/brick1
    Brick3: server3:/rhgs/brick3
    Brick4: server4:/rhgs/brick4

11.8.1. Shrinking a Geo-replicated Volume

  1. Remove a brick using the following command:
    # gluster volume remove-brick VOLNAME BRICK start
    For example:
    # gluster volume remove-brick MASTER_VOL MASTER_HOST:/rhgs/brick2 start
    Remove Brick start successful

    Note

    If the remove-brick command is run with force or without any option, the data on the brick that you are removing will no longer be accessible at the glusterFS mount point. When using the start option, the data is migrated to other bricks, and on a successful commit the removed brick's information is deleted from the volume configuration. Data can still be accessed directly on the brick.
  2. Use geo-replication config checkpoint to ensure that all the data in that brick is synced to the slave.
    1. Set a checkpoint to help verify the status of the data synchronization.
      # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config checkpoint now
    2. Verify the checkpoint completion for the geo-replication session using the following command:
      # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status detail
  3. You can view the status of the remove brick operation using the following command:
    # gluster volume remove-brick VOLNAME BRICK status
    For example:
    # gluster volume remove-brick  MASTER_VOL MASTER_HOST:/rhgs/brick2 status
  4. Stop the geo-replication session between the master and the slave:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop
  5. When the data migration shown in the previous status command is complete, run the following command to commit the brick removal:
    # gluster volume remove-brick VOLNAME BRICK commit
    For example,
    # gluster volume remove-brick  MASTER_VOL MASTER_HOST:/rhgs/brick2 commit
  6. After the brick removal, you can check the volume information using the following command:
    # gluster volume info 
  7. Start the geo-replication session between the hosts:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start

11.8.2. Shrinking a Tiered Volume

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
You can shrink a tiered volume while the trusted storage pool is online and available. For example, you may need to remove a brick that has become inaccessible because of a hardware or network failure.

11.8.2.1. Shrinking a Cold Tier Volume

  1. Detach the tier by performing the steps listed in Section 16.7, “Detaching a Tier from a Volume (Deprecated)”
  2. Remove a brick using the following command:
    # gluster volume remove-brick VOLNAME BRICK start
    For example:
    # gluster volume remove-brick test-volume server2:/rhgs/brick2 start
    Remove Brick start successful

    Note

    If the remove-brick command is run with force or without any option, the data on the brick that you are removing will no longer be accessible at the glusterFS mount point. When using the start option, the data is migrated to other bricks, and on a successful commit the removed brick's information is deleted from the volume configuration. Data can still be accessed directly on the brick.
  3. You can view the status of the remove brick operation using the following command:
    # gluster volume remove-brick VOLNAME BRICK status
    For example:
    # gluster volume remove-brick test-volume server2:/rhgs/brick2 status
          Node    Rebalanced-files          size       scanned      failures         status
     ---------         -----------   -----------   -----------   -----------   ------------
     localhost                  16      16777216            52             0    in progress
    192.168.1.1                 13      16723211            47             0    in progress
  4. When the data migration shown in the previous status command is complete, run the following command to commit the brick removal:
    # gluster volume remove-brick VOLNAME BRICK commit
    For example,
    # gluster volume remove-brick test-volume server2:/rhgs/brick2 commit
  5. Rerun the attach-tier command only with the required set of bricks:
    # gluster volume tier VOLNAME attach [replica COUNT] BRICK...
    For example,
    # gluster volume tier test-volume attach replica 3 server1:/rhgs/tier1 server2:/rhgs/tier2 server1:/rhgs/tier3 server2:/rhgs/tier4

    Important

    When you attach a tier, an internal process called fix-layout commences internally to prepare the hot tier for use. This process takes time and there will a delay in starting the tiering activities.

11.8.2.2. Shrinking a Hot Tier Volume

You must first decide on which bricks should be part of the hot tiered volume and which bricks should be removed from the hot tier volume.
  1. Detach the tier by performing the steps listed in Section 16.7, “Detaching a Tier from a Volume (Deprecated)”
  2. Rerun the attach-tier command only with the required set of bricks:
    # gluster volume tier VOLNAME attach [replica COUNT] brick...

    Important

    When you reattach a tier, an internal process called fix-layout commences internally to prepare the hot tier for use. This process takes time and there will a delay in starting the tiering activities.

11.8.3. Stopping a remove-brick Operation

A remove-brick operation that is in progress can be stopped by using the stop command.

Note

Files that were already migrated during remove-brick operation will not be migrated back to the same brick when the operation is stopped.
To stop remove brick operation, use the following command:
# gluster volume remove-brick VOLNAME BRICK stop
For example:
gluster volume remove-brick test-volume server1:/rhgs/brick1/  server2:/brick2/ stop

Node   Rebalanced-files   size     scanned  failures   skipped   status  run-time in secs
----      -------         ----       ----     ------    -----     -----    ------
localhost     23          376Bytes    34        0        0      stopped      2.00
rhs1          0           0Bytes      88        0        0      stopped      2.00
rhs2          0           0Bytes       0        0        0      not started  0.00
'remove-brick' process may be in the middle of a file migration.
The process will be fully stopped once the migration of the file is complete.
Please check remove-brick process for completion before doing any further brick related tasks on the volume.

11.9. Migrating Volumes

Data can be redistributed across bricks while the trusted storage pool is online and available.Before replacing bricks on the new servers, ensure that the new servers are successfully added to the trusted storage pool.

Note

Before performing a replace-brick operation, review the known issues related to replace-brick operation in the Red Hat Gluster Storage Release Notes.

11.9.1. Replacing a Subvolume on a Distribute or Distribute-replicate Volume

This procedure applies only when at least one brick from the subvolume to be replaced is online. In case of a Distribute volume, the brick that must be replaced must be online. In case of a Distribute-replicate, at least one brick from the subvolume from the replica set that must be replaced must be online.
To replace the entire subvolume with new bricks on a Distribute-replicate volume, follow these steps:
  1. Add the new bricks to the volume.
    # gluster volume add-brick VOLNAME [replica <COUNT>] NEW-BRICK

    Example 11.1. Adding a Brick to a Distribute Volume

    # gluster volume add-brick test-volume server5:/rhgs/brick5
    Add Brick successful
  2. Verify the volume information using the command:
    # gluster volume info
     Volume Name: test-volume
        Type: Distribute
        Status: Started
        Number of Bricks: 5
        Bricks:
        Brick1: server1:/rhgs/brick1
        Brick2: server2:/rhgs/brick2
        Brick3: server3:/rhgs/brick3
        Brick4: server4:/rhgs/brick4
        Brick5: server5:/rhgs/brick5

    Note

    In case of a Distribute-replicate volume, you must specify the replica count in the add-brick command and provide the same number of bricks as the replica count to the add-brick command.
  3. Remove the bricks to be replaced from the subvolume.
    1. Start the remove-brick operation using the command:
      # gluster volume remove-brick VOLNAME [replica <COUNT>] <BRICK> start

      Example 11.2. Start a remove-brick operation on a distribute volume

      # gluster volume remove-brick test-volume server2:/rhgs/brick2 start
      Remove Brick start successful
    2. View the status of the remove-brick operation using the command:
      # gluster volume remove-brick VOLNAME [replica <COUNT>] BRICK status

      Example 11.3. View the Status of remove-brick Operation

      # gluster volume remove-brick test-volume server2:/rhgs/brick2 status
      
      Node   Rebalanced-files size   scanned  failures  skipped   status  run-time in
                                                                            h:m:s
      ----      -------       ----    ----     ------    -----    -----     ------
      server2   10045       204.9MB   73522      0         0     in progress  0:10:34
      
      Estimated time left for rebalance to complete: 0:10:23
      
      Keep monitoring the remove-brick operation status by executing the above command. In the above example, the estimated time for rebalance to complete is 10 minutes. When the value of the status field is set to complete in the output of remove-brick status command, proceed further.
    3. Commit the remove-brick operation using the command:
      # gluster volume remove-brick VOLNAME [replica <COUNT>] <BRICK> commit

      Example 11.4. Commit the remove-brick Operation on a Distribute Volume

      # gluster volume remove-brick test-volume server2:/rhgs/brick2 commit
    4. Verify the volume information using the command:
      # gluster volume info
      Volume Name: test-volume
      Type: Distribute
      Status: Started
      Number of Bricks: 4
      Bricks:
      Brick1: server1:/rhgs/brick1
      Brick3: server3:/rhgs/brick3
      Brick4: server4:/rhgs/brick4
      Brick5: server5:/rhgs/brick5
    5. Verify the content on the brick after committing the remove-brick operation on the volume. If there are any files leftover, copy it through FUSE or NFS mount.
      1. Verify if there are any pending files on the bricks of the subvolume.
        Along with files, all the application-specific extended attributes must be copied. glusterFS also uses extended attributes to store its internal data. The extended attributes used by glusterFS are of the form trusted.glusterfs.*, trusted.afr.*, and trusted.gfid. Any extended attributes other than ones listed above must also be copied.
        To copy the application-specific extended attributes and to achieve a an effect similar to the one that is described above, use the following shell script:
        Syntax:
        # copy.sh <glusterfs-mount-point> <brick>

        Example 11.5. Code Snippet Usage

        If the mount point is /mnt/glusterfs and brick path is /rhgs/brick1, then the script must be run as:
        # copy.sh /mnt/glusterfs /rhgs/brick1
        #!/bin/bash
        
        MOUNT=$1
        BRICK=$2
        
        for file in `find $BRICK ! -type d`; do
            rpath=`echo $file | sed -e "s#$BRICK\(.*\)#\1#g"`
            rdir=`dirname $rpath`
        
            cp -fv $file $MOUNT/$rdir;
        
            for xattr in `getfattr -e hex -m. -d $file 2>/dev/null | sed -e '/^#/d' | grep -v -E "trusted.glusterfs.*" | grep -v -E "trusted.afr.*" | grep -v "trusted.gfid"`;
            do
                key=`echo $xattr | cut -d"=" -f 1`
                value=`echo $xattr | cut -d"=" -f 2`
        
                setfattr $MOUNT/$rpath -n $key -v $value
            done
        done
      2. To identify a list of files that are in a split-brain state, execute the command:
        # gluster volume heal test-volume info split-brain
      3. If there are any files listed in the output of the above command, compare the files across the bricks in a replica set, delete the bad files from the brick and retain the correct copy of the file. Manual intervention by the System Administrator would be required to choose the correct copy of file.

11.9.2. Replacing an Old Brick with a New Brick on a Replicate or Distribute-replicate Volume

A single brick can be replaced during a hardware failure situation, such as a disk failure or a server failure. The brick that must be replaced could either be online or offline. This procedure is applicable for volumes with replication. In case of a Replicate or Distribute-replicate volume types, after replacing the brick, self-heal is automatically triggered to heal the data on the new brick.
Procedure to replace an old brick with a new brick on a Replicate or Distribute-replicate volume:
  1. Ensure that the new brick (server5:/rhgs/brick1) that replaces the old brick (server0:/rhgs/brick1) is empty. Ensure that all the bricks are online. The brick that must be replaced can be in an offline state.
  2. Execute the replace-brick command with the force option:
    # gluster volume replace-brick test-volume server0:/rhgs/brick1 server5:/rhgs/brick1 commit force
    volume replace-brick: success: replace-brick commit successful
  3. Check if the new brick is online.
    # gluster volume status
    Status of volume: test-volume
    Gluster process                    Port    Online    Pid
    ---------------------------------------------------------
    Brick server5:/rhgs/brick1            49156    Y    5731
    
    Brick server1:/rhgs/brick1            49153    Y    5354
    
    Brick server2:/rhgs/brick1            49154    Y    5365
    
    Brick server3:/rhgs/brick1            49155    Y    5376
  4. Data on the newly added brick would automatically be healed. It might take time depending upon the amount of data to be healed. It is recommended to check heal information after replacing a brick to make sure all the data has been healed before replacing/removing any other brick.
    # gluster volume heal VOL_NAME info
    For example:
    # gluster volume heal test-volume info
    Brick server5:/rhgs/brick1
    Status: Connected
    Number of entries: 0
    
    Brick server1:/rhgs/brick1
    Status: Connected
    Number of entries: 0
    
    Brick server2:/rhgs/brick1
    Status: Connected
    Number of entries: 0
    
    Brick server3:/rhgs/brick1
    Status: Connected
    Number of entries: 0
    The value of Number of entries field will be displayed as zero if the heal is complete.

11.9.3. Replacing an Old Brick with a New Brick on a Distribute Volume

  1. Before making any changes, check the contents of the brick that you want to remove from the volume.
    # ls /mount/point/OLDBRICK
    file1
    file2
    ...
    file5
  2. Add the new brick to the volume.
    # gluster volume add-brick VOLNAME NEWSERVER:NEWBRICK
  3. Start removing the old brick.
    # gluster volume remove-brick VOLNAME OLDSERVER:OLDBRICK start
  4. Wait until the remove-brick status command shows that the removal is complete.
    # gluster volume remove-brick VOLNAME BRICK status
              Rebalanced                                                    run time
    Node      files       size    scanned   failures    skipped   status    in secs
    --------------------------------------------------------------------------------
    localhost 5           20Bytes 15        0           0         completed 0.00
    
  5. Finish removing the old brick.
    # gluster volume remove-brick VOLNAME OLDSERVER:OLDBRICK commit
  6. Verify that all files that were on the removed brick are still present on the volume.

11.9.4. Replacing an Old Brick with a New Brick on a Dispersed or Distributed-dispersed Volume

A single brick can be replaced during a hardware failure situation, such as a disk failure or a server failure. The brick that must be replaced could either be online or offline but all other bricks must be online.
Procedure to replace an old brick with a new brick on a Dispersed or Distributed-dispersed volume:
  1. Ensure that the new brick that replaces the old brick is empty. The brick that must be replaced can be in an offline state but all other bricks must be online.
  2. Execute the replace-brick command with the force option:
    # gluster volume replace-brick VOL_NAME old_brick_path new_brick_path  commit force
    
    For example:
    # gluster volume replace-brick test-volume server1:/rhgs/brick2 server1:/rhgs/brick2new  commit force
    volume replace-brick: success: replace-brick commit successful
    The new brick you are adding could be from the same server or you can add a new server and then a new brick.
  3. Check if the new brick is online.
    # gluster volume status
    Status of volume: test-volume
    Gluster process                   TCP Port  RDMA Port  Online    Pid
    ------------------------------------------------------------------------------
    Brick server1:/rhgs/brick1        49187     0          Y       19927
    Brick server1:/rhgs/brick2new     49188     0          Y       19946
    Brick server2:/rhgs/brick3        49189     0          Y       19965
    Brick server2:/rhgs/brick4        49190     0          Y       19984
    Brick server3:/rhgs/brick5        49191     0          Y       20003
    Brick server3:/rhgs/brick6        49192     0          Y       20022
    NFS Server on localhost             N/A       N/A        N       N/A
    Self-heal Daemon on localhost       N/A       N/A        Y       20043
    
    Task Status of Volume test-volume
    ------------------------------------------------------------------------------
    There are no active volume tasks
    
  4. Data on the newly added brick would automatically be healed. It might take time depending upon the amount of data to be healed. It is recommended to check heal information after replacing a brick to make sure all the data has been healed before replacing/removing any other brick.
    # gluster volume heal VOL_NAME info
    For example:
    # gluster volume heal test-volume info
    Brick server1:/rhgs/brick1
    Status: Connected
    Number of entries: 0
    
    Brick server1:/rhgs/brick2new
    Status: Connected
    Number of entries: 0
    
    Brick server2:/rhgs/brick3
    Status: Connected
    Number of entries: 0
    
    Brick server2:/rhgs/brick4
    Status: Connected
    Number of entries: 0
    
    Brick server3:/rhgs/brick5
    Status: Connected
    Number of entries: 0
    
    Brick server3:/rhgs/brick6
    Status: Connected
    Number of entries: 0
    
    The value of Number of entries field will be displayed as zero if the heal is complete.
  5. Red Hat Gluster Storage 3.4 introduces the summary option of heal info command. This command displays the statistics of entries pending heal in split-brain and the entries undergoing healing. This command prints only the entry count and not the actual file-names or gfids.
    To get the summary of a volume, run the following command:
    # gluster volume heal VOLNAME info summary
    For example:
    # gluster volume heal test-volume info summary
                Command output: Brick 192.168.2.8:/brick/1
                Status: Connected
                Total Number of entries: 363
                Number of entries in heal pending: 362
                Number of entries in split-brain: 0
                Number of entries possibly healing: 1
    

    Note

    The ‘summary’ option provides a detailed information about the brick unlike the ‘info’ command. The summary information is obtained in a similar way as the ‘info’ command.
    The --xml parameter provides the output of the summary option in XML format
    # gluster volume heal test-volume info summary --xml
    
    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
      <cliOutput>
        <healInfo<
          <bricks>
            <brick hostUuid="9105dd4b-eca8-4fdb-85b2-b81cdf77eda3">
              <name>192.168.2.8:/brick/1</name>
                <status>Connected</status>
                  <totalNumberOfEntries>363</totalNumberOfEntries>
            <numberOfEntriesInHealPending>362</numberOfEntriesInHealPending>
                <numberOfEntriesInSplitBrain>0</numberOfEntriesInSplitBrain>
          <numberOfEntriesPossiblyHealing>1</numberOfEntriesPossiblyHealing>
                </brick>
              </bricks>
            </healInfo>
          <opRet>0</opRet>
        <opErrno>0</opErrno>
      <opErrstr/>
    </cliOutput>
    

11.9.5. Reconfiguring a Brick in a Volume

The reset-brick subcommand is useful when you want to reconfigure a brick rather than replace it. reset-brick lets you replace a brick with another brick of the same location and UUID. For example, if you initially configured bricks so that they were identified with a hostname, but you want to use that hostname somewhere else, you can use reset-brick to stop the brick, reconfigure it so that it is identified by an IP address instead of the hostname, and return the reconfigured brick to the cluster.
To reconfigure a brick (replace a brick with another brick of the same hostname, path, and UUID), perform the following steps:
  1. Ensure that the quorum minimum will still be met when the brick that you want to reset is taken offline.
  2. If possible, Red Hat recommends stopping I/O, and verifying that no heal operations are pending on the volume.
  3. Run the following command to kill the brick that you want to reset.
    # gluster volume reset-brick VOLNAME HOSTNAME:BRICKPATH start
  4. Configure the offline brick according to your needs.
  5. Check that the volume's Volume ID displayed by gluster volume info matches the volume-id (if any) of the offline brick.
    # gluster volume info VOLNAME
    # cat /var/lib/glusterd/vols/VOLNAME/VOLNAME.HOSTNAME.BRICKPATH.vol | grep volume-id
    For example, in the following dispersed volume, the Volume ID and the volume-id are both ab8a981a-a6d9-42f2-b8a5-0b28fe2c4548.
    # gluster volume info vol
    Volume Name: vol
    Type: Disperse
    Volume ID: ab8a981a-a6d9-42f2-b8a5-0b28fe2c4548
    Status: Started
    Snapshot Count: 0
    Number of Bricks: 1 x (4 + 2) = 6
    Transport-type: tcp
    Bricks:
    Brick1: myhost:/brick/gluster/vol-1
    # cat /var/lib/glusterd/vols/vol/vol.myhost.brick-gluster-vol-1.vol | grep volume-id
    option volume-id ab8a981a-a6d9-42f2-b8a5-0b28fe2c4548
  6. Bring the reconfigured brick back online. There are two options for this:
    • If your brick did not have a volume-id in the previous step, run:
      # gluster volume reset-brick VOLNAME HOSTNAME:BRICKPATH HOSTNAME:BRICKPATH commit
    • If your brick's volume-id matches your volume's identifier, Red Hat recommends adding the force keyword to ensure that the operation succeeds.
      # gluster volume reset-brick VOLNAME HOSTNAME:BRICKPATH HOSTNAME:BRICKPATH commit force

11.10. Replacing Hosts

Before replacing hosts ensure that the new peer has the exact disk capacity as that of the one it is replacing. For example, if the peer in the cluster has two 100GB drives, then the new peer must have the same disk capacity and number of drives. Also, steps described in this section can be performed on other volumes types as well, refer to Section 11.9, “Migrating Volumes” when performing replace and reset operations on the volumes.

11.10.1. Replacing a Host Machine with a Different Hostname

You can replace a failed host machine with another host that has a different hostname. In the following example the original machine which has had an irrecoverable failure is server0.example.com and the replacement machine is server5.example.com. The brick with an unrecoverable failure is server0.example.com:/rhgs/brick1 and the replacement brick is server5.example.com:/rhgs/brick1.
  1. Stop the geo-replication session if configured by executing the following command.
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop force
  2. Probe the new peer from one of the existing peers to bring it into the cluster.
    # gluster peer probe server5.example.com
  3. Ensure that the new brick (server5.example.com:/rhgs/brick1) that is replacing the old brick (server0.example.com:/rhgs/brick1) is empty.
  4. If the geo-replication session is configured, perform the following steps:
    1. Setup the geo-replication session by generating the ssh keys:
      # gluster system:: execute gsec_create 
    2. Create geo-replication session again with force option to distribute the keys from new nodes to Slave nodes.
      # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL create push-pem force
    3. After successfully setting up the shared storage volume, when a new node is replaced in the cluster, the shared storage is not mounted automatically on this node. Neither is the /etc/fstab entry added for the shared storage on this node. To make use of shared storage on this node, execute the following commands:
      # mount -t glusterfs local node's ip:gluster_shared_storage
      /var/run/gluster/shared_storage
      # cp /etc/fstab /var/run/gluster/fstab.tmp
      # echo  local node's ip:/gluster_shared_storage
      /var/run/gluster/shared_storage/ glusterfs defaults 0 0" >> /etc/fstab

      Note

      With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
      For more information on setting up shared storage volume, see Section 11.12, “Setting up Shared Storage Volume”.
    4. Configure the meta-volume for geo-replication:
      # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true
      For more information on configuring meta-volume, see Section 10.3.5, “Configuring a Meta-Volume”.
  5. Retrieve the brick paths in server0.example.com using the following command:
    # gluster volume info <VOLNAME>
    Volume Name: vol
    Type: Replicate
    Volume ID: 0xde822e25ebd049ea83bfaa3c4be2b440
    Status: Started
    Snap Volume: no
    Number of Bricks: 1 x 2 = 2
    Transport-type: tcp
    Bricks:
    Brick1: server0.example.com:/rhgs/brick1
    Brick2: server1.example.com:/rhgs/brick1
    Options Reconfigured:
    cluster.granular-entry-heal: on
    performance.readdir-ahead: on
    snap-max-hard-limit: 256
    snap-max-soft-limit: 90
    auto-delete: disable
    
    Brick path in server0.example.com is /rhgs/brick1. This has to be replaced with the brick in the newly added host, server5.example.com.
  6. Create the required brick path in server5.example.com.For example, if /rhs/brick is the XFS mount point in server5.example.com, then create a brick directory in that path.
    # mkdir /rhgs/brick1
  7. Execute the replace-brick command with the force option:
    # gluster volume replace-brick vol server0.example.com:/rhgs/brick1 server5.example.com:/rhgs/brick1 commit force
    volume replace-brick: success: replace-brick commit successful
  8. Verify that the new brick is online.
    # gluster volume status
    Status of volume: vol
    Gluster process                                  Port    Online Pid
    Brick server5.example.com:/rhgs/brick1           49156    Y    5731
    Brick server1.example.com:/rhgs/brick1            49153    Y    5354
  9. Initiate self-heal on the volume. The status of the heal process can be seen by executing the command:
    # gluster volume heal VOLNAME
  10. The status of the heal process can be seen by executing the command:
    # gluster volume heal VOLNAME info
  11. Detach the original machine from the trusted pool.
    # gluster peer detach (server)
    All clients mounted through the peer which is getting detached need to be remounted, using one of the other active peers in the trusted storage pool, this ensures that the client gets notification on any changes done on the gluster configuration and if the same has been done do you want to proceed? (y/n) y
    peer detach: success
  12. Ensure that after the self-heal completes, the extended attributes are set to zero on the other bricks in the replica.
    # getfattr -d -m. -e hex /rhgs/brick1
    getfattr: Removing leading '/' from absolute path names
    #file: rhgs/brick1
    security.selinux=0x756e636f6e66696e65645f753a6f626a6563745f723a66696c655f743a733000
    trusted.afr.vol-client-0=0x000000000000000000000000
    trusted.afr.vol-client-1=0x000000000000000000000000
    trusted.gfid=0x00000000000000000000000000000001
    trusted.glusterfs.dht=0x0000000100000000000000007ffffffe
    trusted.glusterfs.volume-id=0xde822e25ebd049ea83bfaa3c4be2b440
    In this example, the extended attributes trusted.afr.vol-client-0 and trusted.afr.vol-client-1 have zero values. This means that the data on the two bricks is identical. If these attributes are not zero after self-heal is completed, the data has not been synchronised correctly.
  13. Start the geo-replication session using force option:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start force

11.10.2. Replacing a Host Machine with the Same Hostname

You can replace a failed host with another node having the same FQDN (Fully Qualified Domain Name). A host in a Red Hat Gluster Storage Trusted Storage Pool has its own identity called the UUID generated by the glusterFS Management Daemon.The UUID for the host is available in /var/lib/glusterd/glusterd.info file.
In the following example, the host with the FQDN as server0.example.com was irrecoverable and must to be replaced with a host, having the same FQDN. The following steps have to be performed on the new host.
  1. Stop the geo-replication session if configured by executing the following command.
     # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop force 
  2. Stop the glusterd service on the server0.example.com.
    On RHEL 7 and RHEL 8, run
    # systemctl stop glusterd
    On RHEL 6, run
    # service glusterd stop

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  3. Retrieve the UUID of the failed host (server0.example.com) from another of the Red Hat Gluster Storage Trusted Storage Pool by executing the following command:
    # gluster peer status
    Number of Peers: 2
    
    Hostname: server1.example.com
    Uuid: 1d9677dc-6159-405e-9319-ad85ec030880
    State: Peer in Cluster (Connected)
    
    Hostname: server0.example.com
    Uuid: b5ab2ec3-5411-45fa-a30f-43bd04caf96b
    State: Peer Rejected (Connected)
    
    Note that the UUID of the failed host is b5ab2ec3-5411-45fa-a30f-43bd04caf96b
  4. Edit the glusterd.info file in the new host and include the UUID of the host you retrieved in the previous step.
    # cat /var/lib/glusterd/glusterd.info
    UUID=b5ab2ec3-5411-45fa-a30f-43bd04caf96b
    operating-version=30703

    Note

    The operating version of this node must be same as in other nodes of the trusted storage pool.
  5. Select any host (say for example, server1.example.com) in the Red Hat Gluster Storage Trusted Storage Pool and retrieve its UUID from the glusterd.info file.
    # grep -i uuid /var/lib/glusterd/glusterd.info
    UUID=8cc6377d-0153-4540-b965-a4015494461c
  6. Gather the peer information files from the host (server1.example.com) in the previous step. Execute the following command in that host (server1.example.com) of the cluster.
    # cp -a /var/lib/glusterd/peers /tmp/
  7. Remove the peer file corresponding to the failed host (server0.example.com) from the /tmp/peers directory.
    # rm /tmp/peers/b5ab2ec3-5411-45fa-a30f-43bd04caf96b
    Note that the UUID corresponds to the UUID of the failed host (server0.example.com) retrieved in Step 3.
  8. Archive all the files and copy those to the failed host(server0.example.com).
    # cd /tmp; tar -cvf peers.tar peers
  9. Copy the above created file to the new peer.
    # scp /tmp/peers.tar root@server0.example.com:/tmp
  10. Copy the extracted content to the /var/lib/glusterd/peers directory. Execute the following command in the newly added host with the same name (server0.example.com) and IP Address.
    # tar -xvf /tmp/peers.tar
    # cp peers/* /var/lib/glusterd/peers/
  11. Select any other host in the cluster other than the node (server1.example.com) selected in step 5. Copy the peer file corresponding to the UUID of the host retrieved in Step 5 to the new host (server0.example.com) by executing the following command:
    # scp /var/lib/glusterd/peers/<UUID-retrieved-from-step5> root@Example1:/var/lib/glusterd/peers/
  12. Start the glusterd service.
    # systemctl start glusterd
  13. If new brick has same hostname and same path, refer to Section 11.9.5, “Reconfiguring a Brick in a Volume”, and if it has different hostname and different brick path for replicated volumes then, refer to Section 11.9.2, “Replacing an Old Brick with a New Brick on a Replicate or Distribute-replicate Volume”.
  14. In case of disperse volumes, when a new brick has different hostname and different brick path then, refer to Section 11.9.4, “Replacing an Old Brick with a New Brick on a Dispersed or Distributed-dispersed Volume”.
  15. Perform the self-heal operation on the restored volume.
    # gluster volume heal VOLNAME
  16. You can view the gluster volume self-heal status by executing the following command:
    # gluster volume heal VOLNAME info
  17. If the geo-replication session is configured, perform the following steps:
    1. Setup the geo-replication session by generating the ssh keys:
      # gluster system:: execute gsec_create 
    2. Create geo-replication session again with force option to distribute the keys from new nodes to Slave nodes.
      # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL create push-pem force
    3. After successfully setting up the shared storage volume, when a new node is replaced in the cluster, the shared storage is not mounted automatically on this node. Neither is the /etc/fstab entry added for the shared storage on this node. To make use of shared storage on this node, execute the following commands:
      # mount -t glusterfs <local node's ip>:gluster_shared_storage /var/run/gluster/shared_storage # cp /etc/fstab /var/run/gluster/fstab.tmp # echo "<local node's ip>:/gluster_shared_storage /var/run/gluster/shared_storage/ glusterfs defaults 0 0" >> /etc/fstab 

      Note

      With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .
      For more information on setting up shared storage volume, see Section 11.12, “Setting up Shared Storage Volume”.
    4. Configure the meta-volume for geo-replication:
      # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config use_meta_volume true
    5. Start the geo-replication session using force option:
      # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start force
Replacing a host with the same Hostname in a two-node Red Hat Gluster Storage Trusted Storage Pool

If there are only 2 hosts in the Red Hat Gluster Storage Trusted Storage Pool where the host server0.example.com must be replaced, perform the following steps:

  1. Stop the geo-replication session if configured by executing the following command:
     # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop force 
  2. Stop the glusterd service on server0.example.com.
    On RHEL 7 and RHEL 8, run
    # systemctl stop glusterd
    On RHEL 6, run
    # service glusterd stop

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  3. Retrieve the UUID of the failed host (server0.example.com) from another peer in the Red Hat Gluster Storage Trusted Storage Pool by executing the following command:
    # gluster peer status
    Number of Peers: 1
    
    Hostname: server0.example.com
    Uuid: b5ab2ec3-5411-45fa-a30f-43bd04caf96b
    State: Peer Rejected (Connected)
    
    Note that the UUID of the failed host is b5ab2ec3-5411-45fa-a30f-43bd04caf96b
  4. Edit the glusterd.info file in the new host (server0.example.com) and include the UUID of the host you retrieved in the previous step.
    # cat /var/lib/glusterd/glusterd.info
    UUID=b5ab2ec3-5411-45fa-a30f-43bd04caf96b
    operating-version=30703

    Note

    The operating version of this node must be same as in other nodes of the trusted storage pool.
  5. Create the peer file in the newly created host (server0.example.com) in /var/lib/glusterd/peers/<uuid-of-other-peer> with the name of the UUID of the other host (server1.example.com).
    UUID of the host can be obtained with the following:
    # gluster system:: uuid get

    Example 11.6. Example to obtain the UUID of a host

    For example,
    # gluster system:: uuid get
    UUID: 1d9677dc-6159-405e-9319-ad85ec030880
    In this case the UUID of other peer is 1d9677dc-6159-405e-9319-ad85ec030880
  6. Create a file /var/lib/glusterd/peers/1d9677dc-6159-405e-9319-ad85ec030880 in server0.example.com, with the following command:
    # touch /var/lib/glusterd/peers/1d9677dc-6159-405e-9319-ad85ec030880
    The file you create must contain the following information:
    UUID=<uuid-of-other-node>
    state=3
    hostname=<hostname>
  7. Continue to perform steps 12 to 18 as documented in the previous procedure.

11.11. Rebalancing Volumes

If a volume has been expanded or shrunk using the add-brick or remove-brick commands, the data on the volume needs to be rebalanced among the servers.

Note

In a non-replicated volume, all bricks should be online to perform the rebalance operation using the start option. In a replicated volume, at least one of the bricks in the replica should be online.
To rebalance a volume, use the following command on any of the servers:
# gluster volume rebalance VOLNAME start
For example:
# gluster volume rebalance test-volume start
Starting rebalancing on volume test-volume has been successful
When run without the force option, the rebalance command attempts to balance the space utilized across nodes. Files whose migration would cause the target node to have less available space than the source node are skipped. This results in linkto files being retained, which may cause slower access when a large number of linkto files are present.
Red Hat strongly recommends you to disconnect all the older clients before executing the rebalance command to avoid a potential data loss scenario.

Warning

The Rebalance command can be executed with the force option even when the older clients are connected to the cluster. However, this could lead to a data loss situation.
A rebalance operation with force, balances the data based on the layout, and hence optimizes or does away with the link files, but may lead to an imbalanced storage space used across bricks. This option is to be used only when there are a large number of link files in the system.
To rebalance a volume forcefully, use the following command on any of the servers:
# gluster volume rebalance VOLNAME start force
For example:
# gluster volume rebalance test-volume start force
Starting rebalancing on volume test-volume has been successful

11.11.1. Rebalance Throttling

The rebalance process uses multiple threads to ensure good performance during migration of multiple files. During multiple file migration, there can be a severe impact on storage system performance and a throttling mechanism is provided to manage it.
By default, the rebalance throttling is started in the normal mode. Configure the throttling modes to adjust the rate at which the files must be migrated
# gluster volume set VOLNAME rebal-throttle lazy|normal|aggressive
For example:
# gluster volume set test-volume rebal-throttle lazy

11.11.2. Displaying Rebalance Progress

To display the status of a volume rebalance operation, use the following command:
# gluster volume rebalance VOLNAME status
For example:
# gluster volume rebalance test-volume status
Node          Rebalanced size   scanned failures skipped status      run time
              -files					                                       in h:m:s
------------- ---------- ------ ------- -------- ------- ----------- --------
localhost   71962      70.3GB 380852  0        0       in progress 2:02:20
server1     70489      68.8GB 502185  0        0       in progress 2:02:20
server2     70704      69.0GB 507728  0        0       in progress 2:02:20
server3     71819      70.1GB 435611  0        0       in progress 2:02:20
Estimated time left for rebalance to complete :        2:50:24
A rebalance operation starts a rebalance process on each node of the volume. Each process is responsible for rebalancing the files on its own individual node. Each row of the rebalance status output describes the progress of the operation on a single node.

Important

If there is a reboot while rebalancing the rebalance output might display an incorrect status and some files might not get rebalanced.
Workaround: After the reboot, once the previous rebalance is completed, trigger another rebalance so that the files that were not balanced during the reboot are now rebalanced correctly, and the rebalance output gives the correct status.
The following table describes the output of the rebalance status command:

Table 11.2. Rebalance Status Output Description

Property Name Description
Node The name of the node.
Rebalanced-files The number of files that were successfully migrated.
size The total size of the files that were migrated.
scanned The number of files scanned on the node. This includes the files that were migrated.
failures The number of files that could not be migrated because of errors.
skipped The number of files which were skipped because of various errors or reasons.
status The status of the rebalance operation on the node is in progress, completed, or failed.
run time in h:m:s The amount of time for which the process has been running on the node.
The estimated time left for the rebalance to complete on all nodes is also displayed. The estimated time to complete is displayed only after the rebalance operation has been running for 10 minutes. In cases where the remaining time is extremely large, the estimated time to completion is displayed as >2 months and the user is advised to check again later.
The time taken to complete a rebalance operation depends on the number of files estimated to be on the bricks and the rate at which files are being processed by the rebalance process. This value is recalculated every time the rebalance status command is executed and becomes more accurate the longer rebalance has been running, and for large data sets. The calculation assumes that a file system partition contains a single brick.
A rebalance balance operation is considered complete when the status of every node is completed. For example:
  # gluster volume rebalance test-volume status
  Node       Rebalanced  size   scanned failures skipped status     run time
              -files					                                      in h:m:s
  ---------- ---------- ----- ------- -------- ------- -----------  --------
  node2         0       0Bytes       0       0       0   completed   0:02:23
  node3       234      737.8KB    3350       0     257   completed   0:02:25
  node4         3        14.6K      71       0       6   completed   0:00:02
localhost   317	       1.1MB	  3484       0     155   completed   0:02:38
  volume rebalance: test-volume: success
With this release, details about the files that are skipped during rebalance operation can be obtained. Entries of all such files are available in the rebalance log with the message ID 109126. You can search for the message ID from the log file and get the list of all the skipped files:
For example:
# grep -i 109126 /var/log/glusterfs/test-volume-rebalance.log
[2018-03-15 09:14:30.203393] I [MSGID: 109126] [dht-rebalance.c:2715:gf_defrag_migrate_single_file] 0-test-volume-dht: File migration skipped for /linux-4.9.27/Documentation/ABI/stable/sysfs-fs-orangefs.
[2018-03-15 09:14:31.262969] I [MSGID: 109126] [dht-rebalance.c:2715:gf_defrag_migrate_single_file] 0-test-volume-dht: File migration skipped for /linux-4.9.27/Documentation/ABI/stable/sysfs-devices.
[2018-03-15 09:14:31.842631] I [MSGID: 109126] [dht-rebalance.c:2715:gf_defrag_migrate_single_file] 0-test-volume-dht: File migration skipped for /linux-4.9.27/Documentation/ABI/stable/sysfs-devices-system-cpu.
[2018-03-15 09:14:33.733728] I [MSGID: 109126] [dht-rebalance.c:2715:gf_defrag_migrate_single_file] 0-test-volume-dht: File migration skipped for /linux-4.9.27/Documentation/ABI/testing/sysfs-bus-fcoe.
[2018-03-15 09:14:35.576404] I [MSGID: 109126] [dht-rebalance.c:2715:gf_defrag_migrate_single_file] 0-test-volume-dht: File migration skipped for /linux-4.9.27/Documentation/ABI/testing/sysfs-bus-iio-frequency-ad9523.
[2018-03-15 09:14:43.378480] I [MSGID: 109126] [dht-rebalance.c:2715:gf_defrag_migrate_single_file] 0-test-volume-dht: File migration skipped for /linux-4.9.27/Documentation/DocBook/kgdb.tmpl.
To know more about the failed files, search for 'migrate-data failed' in the rebalance.log file. However, the count for rebalance failed files will not match with "migrate-data failed" in the rebalance.log because the failed count includes all possible failures and just not file migration.

11.11.3. Stopping a Rebalance Operation

To stop a rebalance operation, use the following command:
# gluster volume rebalance VOLNAME stop
For example:
# gluster volume rebalance test-volume stop
Node          Rebalanced size    scanned failures skipped status      run time
              -files					                                        in h:m:s
------------- ---------- ------- ------- -------- ------- ----------- --------
localhost     106504     104.0GB 558111  0        0       stopped     3:02:24
server1       102299      99.9GB 725239  0        0       stopped     3:02:24
server2       102264      99.9GB 737364  0        0       stopped     3:02:24
server3       106813     104.3GB 646581  0        0       stopped     3:02:24
Estimated time left for rebalance to complete :        2:06:38

11.12. Setting up Shared Storage Volume

Features like Snapshot Scheduler, NFS Ganesha and geo-replication require a shared storage to be available across all nodes of the cluster. A gluster volume named gluster_shared_storage is made available for this purpose, and is facilitated by the following volume set option.
cluster.enable-shared-storage
This option accepts the following two values:
  • enable

    When the volume set option is enabled, a gluster volume named gluster_shared_storage is created in the cluster, and is mounted at /var/run/gluster/shared_storage on all the nodes in the cluster.

    Note

    With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .

    Note

    • This option cannot be enabled if there is only one node present in the cluster, or if only one node is online in the cluster.
    • The volume created is a replica 3 volume. This depends on the number of nodes which are online in the cluster at the time of enabling this option and each of these nodes will have one brick participating in the volume. The brick path participating in the volume is /var/lib/glusterd/ss_brick.
    • The mount entry is also added to /etc/fstab as part of enable.
    • Before enabling this feature make sure that there is no volume named gluster_shared_storage in the cluster. This volume name is reserved for internal use only
    After successfully setting up the shared storage volume, when a new node is added to the cluster, the shared storage is not mounted automatically on this node. Neither is the /etc/fstab entry added for the shared storage on this node. To make use of shared storage on this node, execute the following commands:
    # mount -t glusterfs <local node's ip>:gluster_shared_storage
    /var/run/gluster/shared_storage
    # cp /etc/fstab /var/run/gluster/fstab.tmp
    # echo "<local node's ip>:/gluster_shared_storage
    /var/run/gluster/shared_storage/ glusterfs defaults 0 0" >> /etc/fstab
  • disable

    When the volume set option is disabled, the gluster_shared_storage volume is unmounted on all the nodes in the cluster, and then the volume is deleted. The mount entry from /etc/fstab as part of disable is also removed.

For example:
# gluster volume set all cluster.enable-shared-storage enable
volume set: success

Important

After creating a cluster excute the following command on all nodes present in the cluster:
systemctl enable glusterfssharedstorage.service
This is applicable for Red Hat Enterpise Linux 7 (RHEL 7) and Red Hat Enterpise Linux 8 (RHEL 8).

11.13. Stopping Volumes

To stop a volume, use the following command:
# gluster volume stop VOLNAME
For example, to stop test-volume:
# gluster volume stop test-volume
Stopping volume will make its data inaccessible. Do you want to continue? (y/n) y
Stopping volume test-volume has been successful

11.14. Deleting Volumes

Important

Volumes must be unmounted and stopped before you can delete them. Ensure that you also remove entries relating to this volume from the /etc/fstab file after the volume has been deleted.
To delete a volume, use the following command:
# gluster volume delete VOLNAME
For example, to delete test-volume:
# gluster volume delete test-volume
Deleting volume will erase all information about the volume. Do you want to continue? (y/n) y
Deleting volume test-volume has been successful

11.15. Managing Split-brain

Split-brain is a state of data inconsistency that occurs when different data sources in a cluster having different ideas about what the correct, current state of that data should be. This can happen because of servers in a network design, or a failure condition based on servers not communicating and synchronizing their data to each other.
In Red Hat Gluster Storage, split-brain is a term applicable to Red Hat Gluster Storage volumes in a replicate configuration. A file is said to be in split-brain when the copies of the same file in different bricks that constitute the replica-pair have mismatching data and/or metadata contents such that they are conflicting each other and automatic healing is not possible. In this scenario, you can decide which is the correct file (source) and which is the one that requires healing (sink) by inspecting at the mismatching files from the backend bricks.
The AFR translator in glusterFS makes use of extended attributes to keep track of the operations on a file. These attributes determine which brick is the correct source when a file requires healing. If the files are clean, the extended attributes are all zeroes indicating that no heal is necessary. When a heal is required, they are marked in such a way that there is a distinguishable source and sink and the heal can happen automatically. But, when a split-brain occurs, these extended attributes are marked in such a way that both bricks mark themselves as sources, making automatic healing impossible.
Split-brain occurs when a difference exists between multiple copies of the same file, and Red Hat Gluster Storage is unable to determine which version is correct. Applications are restricted from executing certain operations like read and write on the disputed file when split-brain happens. Attempting to access the files results in the application receiving an input/output error on the disputed file.
The three types of split-brain that occur in Red Hat Gluster Storage are:

11.15.1. Preventing Split-brain

To prevent split-brain in the trusted storage pool, you must configure server-side and client-side quorum.

11.15.1.1. Configuring Server-Side Quorum

The quorum configuration in a trusted storage pool determines the number of server failures that the trusted storage pool can sustain. If an additional failure occurs, the trusted storage pool will become unavailable. If too many server failures occur, or if there is a problem with communication between the trusted storage pool nodes, it is essential that the trusted storage pool be taken offline to prevent data loss.
After configuring the quorum ratio at the trusted storage pool level, you must enable the quorum on a particular volume by setting cluster.server-quorum-type volume option as server. For more information on this volume option, see Section 11.1, “Configuring Volume Options”.
Configuration of the quorum is necessary to prevent network partitions in the trusted storage pool. Network Partition is a scenario where, a small set of nodes might be able to communicate together across a functioning part of a network, but not be able to communicate with a different set of nodes in another part of the network. This can cause undesirable situations, such as split-brain in a distributed system. To prevent a split-brain situation, all the nodes in at least one of the partitions must stop running to avoid inconsistencies.
This quorum is on the server-side, that is, the glusterd service. Whenever the glusterd service on a machine observes that the quorum is not met, it brings down the bricks to prevent data split-brain. When the network connections are brought back up and the quorum is restored, the bricks in the volume are brought back up. When the quorum is not met for a volume, any commands that update the volume configuration or peer addition or detach are not allowed. It is to be noted that both, the glusterd service not running and the network connection between two machines being down are treated equally.
You can configure the quorum percentage ratio for a trusted storage pool. If the percentage ratio of the quorum is not met due to network outages, the bricks of the volume participating in the quorum in those nodes are taken offline. By default, the quorum is met if the percentage of active nodes is more than 50% of the total storage nodes. However, if the quorum ratio is manually configured, then the quorum is met only if the percentage of active storage nodes of the total storage nodes is greater than or equal to the set value.
To configure the quorum ratio, use the following command:
# gluster volume set all cluster.server-quorum-ratio PERCENTAGE
For example, to set the quorum to 51% of the trusted storage pool:
# gluster volume set all cluster.server-quorum-ratio 51%
In this example, the quorum ratio setting of 51% means that more than half of the nodes in the trusted storage pool must be online and have network connectivity between them at any given time. If a network disconnect happens to the storage pool, then the bricks running on those nodes are stopped to prevent further writes.
You must ensure to enable the quorum on a particular volume to participate in the server-side quorum by running the following command:
# gluster volume set VOLNAME cluster.server-quorum-type server

Important

For a two-node trusted storage pool, it is important to set the quorum ratio to be greater than 50% so that two nodes separated from each other do not both believe they have a quorum.
For a replicated volume with two nodes and one brick on each machine, if the server-side quorum is enabled and one of the nodes goes offline, the other node will also be taken offline because of the quorum configuration. As a result, the high availability provided by the replication is ineffective. To prevent this situation, a dummy node can be added to the trusted storage pool which does not contain any bricks. This ensures that even if one of the nodes which contains data goes offline, the other node will remain online. Note that if the dummy node and one of the data nodes goes offline, the brick on other node will be also be taken offline, and will result in data unavailability.

11.15.1.2. Configuring Client-Side Quorum

By default, when replication is configured, clients can modify files as long as at least one brick in the replica group is available. If network partitioning occurs, different clients are only able to connect to different bricks in a replica set, potentially allowing different clients to modify a single file simultaneously.
For example, imagine a three-way replicated volume is accessed by two clients, C1 and C2, who both want to modify the same file. If network partitioning occurs such that client C1 can only access brick B1, and client C2 can only access brick B2, then both clients are able to modify the file independently, creating split-brain conditions on the volume. The file becomes unusable, and manual intervention is required to correct the issue.
Client-side quorum allows administrators to set a minimum number of bricks that a client must be able to access in order to allow data in the volume to be modified. If client-side quorum is not met, files in the replica set are treated as read-only. This is useful when three-way replication is configured.
Client-side quorum is configured on a per-volume basis, and applies to all replica sets in a volume. If client-side quorum is not met for X of Y volume sets, only X volume sets are treated as read-only; the remaining volume sets continue to allow data modification.
Earlier, the replica subvolume turned read-only when the quorum does not met. With rhgs-3.4.3, the subvolume becomes unavailable as all the file operations fail with ENOTCONN error instead of becoming EROFS. This means the cluster.quorum-reads volume option is also not supported.

Client-Side Quorum Options

cluster.quorum-count
The minimum number of bricks that must be available in order for writes to be allowed. This is set on a per-volume basis. Valid values are between 1 and the number of bricks in a replica set. This option is used by the cluster.quorum-type option to determine write behavior.
This option is used in conjunction with cluster.quorum-type =fixed option to specify the number of bricks to be active to participate in quorum. If the quorum-type is auto then this option has no significance.
cluster.quorum-type
Determines when the client is allowed to write to a volume. Valid values are fixed and auto.
If cluster.quorum-type is fixed, writes are allowed as long as the number of bricks available in the replica set is greater than or equal to the value of the cluster.quorum-count option.
If cluster.quorum-type is auto, writes are allowed when at least 50% of the bricks in a replica set are be available. In a replica set with an even number of bricks, if exactly 50% of the bricks are available, the first brick in the replica set must be available in order for writes to continue.
In a three-way replication setup, it is recommended to set cluster.quorum-type to auto to avoid split-brains. If the quorum is not met, the replica pair becomes read-only.

Example 11.7. Client-Side Quorum

In the above scenario, when the client-side quorum is not met for replica group A, only replica group A becomes read-only. Replica groups B and C continue to allow data modifications.
Configure the client-side quorum using cluster.quorum-type and cluster.quorum-count options.

Important

When you integrate Red Hat Gluster Storage with Red Hat Enterprise Virtualization, the client-side quorum is enabled when you run gluster volume set VOLNAME group virt command. If on a two replica set up, if the first brick in the replica pair is offline, virtual machines will be paused because quorum is not met and writes are disallowed.
Consistency is achieved at the cost of fault tolerance. If fault-tolerance is preferred over consistency, disable client-side quorum with the following command:
# gluster volume reset VOLNAME quorum-type
Example - Setting up server-side and client-side quorum to avoid split-brain scenario

This example provides information on how to set server-side and client-side quorum on a Distribute Replicate volume to avoid split-brain scenario. The configuration of this example has 3 X 3 ( 9 bricks) Distribute Replicate setup.

# gluster volume info testvol
Volume Name: testvol
Type: Distributed-Replicate
Volume ID: 0df52d58-bded-4e5d-ac37-4c82f7c89cfh
Status: Created
Number of Bricks: 3 x 3 = 9
Transport-type: tcp
Bricks:
Brick1: server1:/rhgs/brick1
Brick2: server2:/rhgs/brick2
Brick3: server3:/rhgs/brick3
Brick4: server4:/rhgs/brick4
Brick5: server5:/rhgs/brick5
Brick6: server6:/rhgs/brick6
Brick7: server7:/rhgs/brick7
Brick8: server8:/rhgs/brick8
Brick9: server9:/rhgs/brick9
Setting Server-side Quorum
Enable the quorum on a particular volume to participate in the server-side quorum by running the following command:
# gluster volume set VOLNAME cluster.server-quorum-type server
Set the quorum to 51% of the trusted storage pool:
# gluster volume set all cluster.server-quorum-ratio 51%
In this example, the quorum ratio setting of 51% means that more than half of the nodes in the trusted storage pool must be online and have network connectivity between them at any given time. If a network disconnect happens to the storage pool, then the bricks running on those nodes are stopped to prevent further writes.
Setting Client-side Quorum
Set the quorum-typeoption to auto to allow writes to the file only if the percentage of active replicate bricks is more than 50% of the total number of bricks that constitute that replica.
# gluster volume set VOLNAME quorum-type auto
In this example, as there are only two bricks in the replica pair, the first brick must be up and running to allow writes.

Important

Atleast n/2 bricks need to be up for the quorum to be met. If the number of bricks (n) in a replica set is an even number, it is mandatory that the n/2 count must consist of the primary brick and it must be up and running. If n is an odd number, the n/2 count can have any brick up and running, that is, the primary brick need not be up and running to allow writes.

11.15.2. Recovering from File Split-brain

You can recover from the data and meta-data split-brain using one of the following methods:
For information on resolving entry/type-mismatch split-brain, see Chapter 23, Manually Recovering File Split-brain .

11.15.2.1.  Recovering File Split-brain from the Mount Point

Steps to recover from a split-brain from the mount point

  1. You can use a set of getfattr and setfattr commands to detect the data and meta-data split-brain status of a file and resolve split-brain from the mount point.

    Important

    This process for split-brain resolution from mount will not work on NFS mounts as it does not provide extended attributes support.
    In this example, the test-volume volume has bricks brick0, brick1, brick2 and brick3.
    # gluster volume info test-volume
    Volume Name: test-volume
    Type: Distributed-Replicate
    Status: Started
    Number of Bricks: 2 x 2 = 4
    Transport-type: tcp
    Bricks:
    Brick1: test-host:/rhgs/brick0
    Brick2: test-host:/rhgs/brick1
    Brick3: test-host:/rhgs/brick2
    Brick4: test-host:/rhgs/brick3
    Directory structure of the bricks is as follows:
    # tree -R /test/b?
    /rhgs/brick0
    ├── dir
    │   └── a
    └── file100
    
    /rhgs/brick1
    ├── dir
    │   └── a
    └── file100
    
    /rhgs/brick2
    ├── dir
    ├── file1
    ├── file2
    └── file99
    
    /rhgs/brick3
    ├── dir
    ├── file1
    ├── file2
    └── file99
    In the following output, some of the files in the volume are in split-brain.
    # gluster volume heal test-volume info split-brain
    Brick test-host:/rhgs/brick0/
    /file100
    /dir
    Number of entries in split-brain: 2
    
    Brick test-host:/rhgs/brick1/
    /file100
    /dir
    Number of entries in split-brain: 2
    
    Brick test-host:/rhgs/brick2/
    /file99
    <gfid:5399a8d1-aee9-4653-bb7f-606df02b3696>
    Number of entries in split-brain: 2
    
    Brick test-host:/rhgs/brick3/
    <gfid:05c4b283-af58-48ed-999e-4d706c7b97d5>
    <gfid:5399a8d1-aee9-4653-bb7f-606df02b3696>
    Number of entries in split-brain: 2
    To know data or meta-data split-brain status of a file:
    # getfattr -n replica.split-brain-status <path-to-file>
    The above command executed from mount provides information if a file is in data or meta-data split-brain. This command is not applicable to entry/type-mismatch split-brain.
    For example,
    • file100 is in meta-data split-brain. Executing the above mentioned command for file100 gives :
      # getfattr -n replica.split-brain-status file100
      # file: file100
      replica.split-brain-status="data-split-brain:no    metadata-split-brain:yes    Choices:test-client-0,test-client-1"
    • file1 is in data split-brain.
      # getfattr -n replica.split-brain-status file1
      # file: file1
      replica.split-brain-status="data-split-brain:yes    metadata-split-brain:no    Choices:test-client-2,test-client-3"
    • file99 is in both data and meta-data split-brain.
      # getfattr -n replica.split-brain-status file99
      # file: file99
      replica.split-brain-status="data-split-brain:yes    metadata-split-brain:yes    Choices:test-client-2,test-client-3"
    • dir is in entry/type-mismatch split-brain but as mentioned earlier, the above command is does not display if the file is in entry/type-mismatch split-brain. Hence, the command displays The file is not under data or metadata split-brain. For information on resolving entry/type-mismatch split-brain, see Chapter 23, Manually Recovering File Split-brain .
      # getfattr -n replica.split-brain-status dir
      # file: dir
      replica.split-brain-status="The file is not under data or metadata split-brain"
    • file2 is not in any kind of split-brain.
      # getfattr -n replica.split-brain-status file2
      # file: file2
      replica.split-brain-status="The file is not under data or metadata split-brain"
  2. Analyze the files in data and meta-data split-brain and resolve the issue

    When you perform operations like cat, getfattr, and more from the mount on files in split-brain, it throws an input/output error. For further analyzing such files, you can use setfattr command.

    # setfattr -n replica.split-brain-choice -v "choiceX" <path-to-file>
    Using this command, a particular brick can be chosen to access the file in split-brain.
    For example,
    file1 is in data-split-brain and when you try to read from the file, it throws input/output error.
    # cat file1
    cat: file1: Input/output error
    Split-brain choices provided for file1 were test-client-2 and test-client-3.
    Setting test-client-2 as split-brain choice for file1 serves reads from b2 for the file.
    # setfattr -n replica.split-brain-choice -v test-client-2 file1
    Now, you can perform operations on the file. For example, read operations on the file:
    # cat file1
    xyz
    Similarly, to inspect the file from other choice, replica.split-brain-choice is to be set to test-client-3.
    Trying to inspect the file from a wrong choice errors out. You can undo the split-brain-choice that has been set, the above mentioned setfattr command can be used with none as the value for extended attribute.
    For example,
    # setfattr -n replica.split-brain-choice -v none file1
    Now performing cat operation on the file will again result in input/output error, as before.
    # cat file
    cat: file1: Input/output error
    After you decide which brick to use as a source for resolving the split-brain, it must be set for the healing to be done.
    # setfattr -n replica.split-brain-heal-finalize -v <heal-choice> <path-to-file>
    Example
    # setfattr -n replica.split-brain-heal-finalize -v test-client-2 file1
    The above process can be used to resolve data and/or meta-data split-brain on all the files.
    Setting the split-brain-choice on the file
    After setting the split-brain-choice on the file, the file can be analyzed only for five minutes. If the duration of analyzing the file needs to be increased, use the following command and set the required time in timeout-in-minute argument.
    # setfattr -n replica.split-brain-choice-timeout -v <timeout-in-minutes> <mount_point/file>
    This is a global timeout and is applicable to all files as long as the mount exists. The timeout need not be set each time a file needs to be inspected but for a new mount it will have to be set again for the first time. This option becomes invalid if the operations like add-brick or remove-brick are performed.

    Note

    If fopen-keep-cache FUSE mount option is disabled, then inode must be invalidated each time before selecting a new replica.split-brain-choice to inspect a file using the following command:
    # setfattr -n inode-invalidate -v 0 <path-to-file>

11.15.2.2. Recovering File Split-brain from the gluster CLI

You can resolve the split-brain from the gluster CLI by the following ways:
  • Use bigger-file as source
  • Use the file with latest mtime as source
  • Use one replica as source for a particular file
  • Use one replica as source for all files

    Note

    The entry/type-mismatch split-brain resolution is not supported using CLI. For information on resolving entry/type-mismatch split-brain, see Chapter 23, Manually Recovering File Split-brain .
Selecting the bigger-file as source

This method is useful for per file healing and where you can decided that the file with bigger size is to be considered as source.

  1. Run the following command to obtain the list of files that are in split-brain:
    # gluster volume heal VOLNAME info split-brain
    Brick <hostname:brickpath-b1>
    <gfid:aaca219f-0e25-4576-8689-3bfd93ca70c2>
    <gfid:39f301ae-4038-48c2-a889-7dac143e82dd>
    <gfid:c3c94de2-232d-4083-b534-5da17fc476ac>
    Number of entries in split-brain: 3
    
    Brick <hostname:brickpath-b2>
    /dir/file1
    /dir
    /file4
    Number of entries in split-brain: 3
    From the command output, identify the files that are in split-brain.
    You can find the differences in the file size and md5 checksums by performing a stat and md5 checksums on the file from the bricks. The following is the stat and md5 checksum output of a file:
    On brick b1:
    # stat b1/dir/file1
      File: ‘b1/dir/file1’
      Size: 17              Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919362      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 13:55:40.149897333 +0530
    Modify: 2015-03-06 13:55:37.206880347 +0530
    Change: 2015-03-06 13:55:37.206880347 +0530
     Birth: -
    
    # md5sum b1/dir/file1
    040751929ceabf77c3c0b3b662f341a8  b1/dir/file1
    
    On brick b2:
    # stat b2/dir/file1
      File: ‘b2/dir/file1’
      Size: 13              Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919365      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 13:54:22.974451898 +0530
    Modify: 2015-03-06 13:52:22.910758923 +0530
    Change: 2015-03-06 13:52:22.910758923 +0530
     Birth: -
    
    # md5sum b2/dir/file1
    cb11635a45d45668a403145059c2a0d5  b2/dir/file1
    You can notice the differences in the file size and md5 checksums.
  2. Execute the following command along with the full file name as seen from the root of the volume (or) the gfid-string representation of the file, which is displayed in the heal info command's output.
    # gluster volume heal <VOLNAME> split-brain bigger-file <FILE>
    For example,
    # gluster volume heal test-volume split-brain bigger-file /dir/file1
    Healed /dir/file1.
After the healing is complete, the md5sum and file size on both bricks must be same. The following is a sample output of the stat and md5 checksums command after completion of healing the file.
On brick b1:
# stat b1/dir/file1
  File: ‘b1/dir/file1’
  Size: 17              Blocks: 16         IO Block: 4096   regular file
Device: fd03h/64771d    Inode: 919362      Links: 2
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2015-03-06 14:17:27.752429505 +0530
Modify: 2015-03-06 13:55:37.206880347 +0530
Change: 2015-03-06 14:17:12.880343950 +0530
 Birth: -

# md5sum b1/dir/file1
040751929ceabf77c3c0b3b662f341a8  b1/dir/file1

On brick b2:
# stat b2/dir/file1
  File: ‘b2/dir/file1’
  Size: 17              Blocks: 16         IO Block: 4096   regular file
Device: fd03h/64771d    Inode: 919365      Links: 2
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2015-03-06 14:17:23.249403600 +0530
Modify: 2015-03-06 13:55:37.206880000 +0530
Change: 2015-03-06 14:17:12.881343955 +0530
 Birth: -

# md5sum b2/dir/file1
040751929ceabf77c3c0b3b662f341a8  b2/dir/file1
Selecting the file with latest mtime as source

This method is useful for per file healing and if you want the file with latest mtime has to be considered as source.

  1. Run the following command to obtain the list of files that are in split-brain:
    # gluster volume heal VOLNAME info split-brain
    Brick <hostname:brickpath-b1>
    <gfid:aaca219f-0e25-4576-8689-3bfd93ca70c2>
    <gfid:39f301ae-4038-48c2-a889-7dac143e82dd>
    <gfid:c3c94de2-232d-4083-b534-5da17fc476ac>
    Number of entries in split-brain: 3
    
    Brick <hostname:brickpath-b2>
    /dir/file1
    /dir
    /file4
    Number of entries in split-brain: 3
    From the command output, identify the files that are in split-brain.
    You can find the differences in the file size and md5 checksums by performing a stat and md5 checksums on the file from the bricks. The following is the stat and md5 checksum output of a file:
    On brick b1:
    
     stat b1/file4
      File: ‘b1/file4’
        Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919356      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 13:53:19.417085062 +0530
    Modify: 2015-03-06 13:53:19.426085114 +0530
    Change: 2015-03-06 13:53:19.426085114 +0530
     Birth: -
    
    
    # md5sum b1/file4
    b6273b589df2dfdbd8fe35b1011e3183  b1/file4
    
    On brick b2:
    
    # stat b2/file4
      File: ‘b2/file4’
      Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919358      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 13:52:35.761833096 +0530
    Modify: 2015-03-06 13:52:35.769833142 +0530
    Change: 2015-03-06 13:52:35.769833142 +0530
     Birth: -
    
    
    # md5sum b2/file4
    0bee89b07a248e27c83fc3d5951213c1  b2/file4
    You can notice the differences in the md5 checksums, and the modify time.
  2. Execute the following command
    # gluster volume heal <VOLNAME> split-brain latest-mtime <FILE>
    In this command, FILE can be either the full file name as seen from the root of the volume or the gfid-string representation of the file.
    For example,
    # gluster volume heal test-volume split-brain latest-mtime /file4
    Healed /file4
    
    After the healing is complete, the md5 checksum, file size, and modify time on both bricks must be same. The following is a sample output of the stat and md5 checksums command after completion of healing the file. You can notice that the file has been healed using the brick having the latest mtime (brick b1, in this example) as the source.
    On brick b1:
    # stat b1/file4
      File: ‘b1/file4’
      Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919356      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 14:23:38.944609863 +0530
    Modify: 2015-03-06 13:53:19.426085114 +0530
    Change: 2015-03-06 14:27:15.058927962 +0530
     Birth: -
    
    # md5sum b1/file4
    b6273b589df2dfdbd8fe35b1011e3183  b1/file4
    
    On brick b2:
    # stat b2/file4
     File: ‘b2/file4’
       Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919358      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 14:23:38.944609000 +0530
    Modify: 2015-03-06 13:53:19.426085000 +0530
    Change: 2015-03-06 14:27:15.059927968 +0530
     Birth:
    
    # md5sum b2/file4
    b6273b589df2dfdbd8fe35b1011e3183  b2/file4
Selecting one replica as source for a particular file

This method is useful if you know which file is to be considered as source.

  1. Run the following command to obtain the list of files that are in split-brain:
    # gluster volume heal VOLNAME info split-brain
    Brick <hostname:brickpath-b1>
    <gfid:aaca219f-0e25-4576-8689-3bfd93ca70c2>
    <gfid:39f301ae-4038-48c2-a889-7dac143e82dd>
    <gfid:c3c94de2-232d-4083-b534-5da17fc476ac>
    Number of entries in split-brain: 3
    
    Brick <hostname:brickpath-b2>
    /dir/file1
    /dir
    /file4
    Number of entries in split-brain: 3
    From the command output, identify the files that are in split-brain.
    You can find the differences in the file size and md5 checksums by performing a stat and md5 checksums on the file from the bricks. The following is the stat and md5 checksum output of a file:
    On brick b1:
    
     stat b1/file4
      File: ‘b1/file4’
      Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919356      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 13:53:19.417085062 +0530
    Modify: 2015-03-06 13:53:19.426085114 +0530
    Change: 2015-03-06 13:53:19.426085114 +0530
     Birth: -
    
    # md5sum b1/file4
    b6273b589df2dfdbd8fe35b1011e3183  b1/file4
    
    On brick b2:
    
    # stat b2/file4
      File: ‘b2/file4’
      Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919358      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 13:52:35.761833096 +0530
    Modify: 2015-03-06 13:52:35.769833142 +0530
    Change: 2015-03-06 13:52:35.769833142 +0530
     Birth: -
    
    # md5sum b2/file4
    0bee89b07a248e27c83fc3d5951213c1  b2/file4
    You can notice the differences in the file size and md5 checksums.
  2. Execute the following command
    # gluster volume heal <VOLNAME> split-brain source-brick <HOSTNAME:BRICKNAME> <FILE>
    In this command, FILE present in <HOSTNAME:BRICKNAME> is taken as source for healing.
    For example,
    # gluster volume heal test-volume split-brain source-brick test-host:b1 /file4
    Healed /file4
    After the healing is complete, the md5 checksum and file size on both bricks must be same. The following is a sample output of the stat and md5 checksums command after completion of healing the file.
    On brick b1:
    # stat b1/file4
      File: ‘b1/file4’
      Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919356      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 14:23:38.944609863 +0530
    Modify: 2015-03-06 13:53:19.426085114 +0530
    Change: 2015-03-06 14:27:15.058927962 +0530
     Birth: -
    
    # md5sum b1/file4
    b6273b589df2dfdbd8fe35b1011e3183  b1/file4
    
    On brick b2:
    # stat b2/file4
     File: ‘b2/file4’
      Size: 4               Blocks: 16         IO Block: 4096   regular file
    Device: fd03h/64771d    Inode: 919358      Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2015-03-06 14:23:38.944609000 +0530
    Modify: 2015-03-06 13:53:19.426085000 +0530
    Change: 2015-03-06 14:27:15.059927968 +0530
     Birth: -
    
    # md5sum b2/file4
    b6273b589df2dfdbd8fe35b1011e3183  b2/file4
Selecting one replica as source for all files

This method is useful if you know want to use a particular brick as a source for the split-brain files in that replica pair.

  1. Run the following command to obtain the list of files that are in split-brain:
    # gluster volume heal VOLNAME info split-brain
    From the command output, identify the files that are in split-brain.
  2. Execute the following command
    # gluster volume heal <VOLNAME> split-brain source-brick <HOSTNAME:BRICKNAME>
    In this command, for all the files that are in split-brain in this replica, <HOSTNAME:BRICKNAME> is taken as source for healing.
    For example,
    # gluster volume heal test-volume split-brain source-brick test-host:b1

11.15.3. Recovering GFID Split-brain from the gluster CLI

With this release, Red Hat Gluster Storage allows you to resolve GFID split-brain from the gluster CLI.
You can use one of the following policies to resolve GFID split-brain:
  • Use bigger-file as source
  • Use the file with latest mtime as source
  • Use one replica as source for a particular file

Note

The entry/type-mismatch split-brain resolution is not supported using CLI. For information on resolving entry/type-mismatch split-brain, see Chapter 23, Manually Recovering File Split-brain .
Selecting the bigger-file as source

This method is useful for per file healing and where you can decided that the file with bigger size is to be considered as source.

  1. Run the following command to obtain the path of the file that is in split-brain:
      # gluster volume heal VOLNAME info split-brain
    From the output, identify the files for which file operations performed from the client failed with input/output error.
    For example,
    # gluster volume heal 12 info split-brain
    Brick 10.70.47.45:/bricks/brick2/b0
    /f5
    / - Is in split-brain
    
    Status: Connected
    Number of entries: 2
    
    Brick 10.70.47.144:/bricks/brick2/b1
    /f5
    / - Is in split-brain
    
    Status: Connected
    Number of entries: 2
    
    In the above command, 12 is the volume name, b0 and b1 are the bricks.
  2. Execute the below command on the brick to fetch information if a file is in GFID split-brain. The getfattr command is used to obtain and verify the AFR changelog extended attributes of the files.
        # getfattr -d -e hex -m. <path-to-file>
    For example,
    On brick /b0
    
    # getfattr -d -m . -e hex /bricks/brick2/b0/f5
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b0/f5
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.afr.12-client-1=0x000000020000000100000000
    trusted.afr.dirty=0x000000000000000000000000
    trusted.gfid=0xce0a9956928e40afb78e95f78defd64f
    trusted.gfid2path.9cde09916eabc845=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6635
    
    
    
    On brick /b1
    
    # getfattr -d -m . -e hex /bricks/brick2/b1/f5
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b1/f5
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.afr.12-client-0=0x000000020000000100000000
    trusted.afr.dirty=0x000000000000000000000000
    trusted.gfid=0x9563544118653550e888ab38c232e0c
    trusted.gfid2path.9cde09916eabc845=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6635
    
    You can notice the difference in GFID for the file f5 in both the bricks.
    You can find the differences in the file size by executing stat command on the file from the bricks. The following is the output of the file f5 in bricks b0 and b1:
    On brick /b0
    
    # stat /bricks/brick2/b0/f5
    File: ‘/bricks/brick2/b0/f5’
    Size: 15            Blocks: 8          IO Block: 4096   regular file
    Device: fd15h/64789d    Inode: 67113350    Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: system_u:object_r:glusterd_brick_t:s0
    Access: 2018-08-29 20:46:26.353751073 +0530
    Modify: 2018-08-29 20:46:26.361751203 +0530
    Change: 2018-08-29 20:47:16.363751236 +0530
    Birth: -
    
    
    
    On brick /b1
    
    # stat /bricks/brick2/b1/f5
    File: ‘/bricks/brick2/b1/f5’
    Size: 2             Blocks: 8          IO Block: 4096   regular file
    Device: fd15h/64789d    Inode: 67111750    Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: system_u:object_r:glusterd_brick_t:s0
    Access: 2018-08-29 20:44:56.153301616 +0530
    Modify: 2018-08-29 20:44:56.161301745 +0530
    Change: 2018-08-29 20:44:56.162301761 +0530
    Birth: -
    
  3. Execute the following command along with the full filename as seen from the root of the volume which is displayed in the heal info command's output:
    # gluster volume heal VOLNAME split-brain bigger-file FILE
    For example,
    # gluster volume heal12 split-brain bigger-file /f5
    GFID split-brain resolved for file /f5
    
    After the healing is complete, the file size on both bricks must be the same as that of the file which had the bigger size. The following is a sample output of the getfattrcommand after completion of healing the file.
    On brick /b0
    
    # getfattr -d -m . -e hex /bricks/brick2/b0/f5
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b0/f5
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.gfid=0xce0a9956928e40afb78e95f78defd64f
    trusted.gfid2path.9cde09916eabc845=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6635
    
    
    
    On brick /b1
    
    # getfattr -d -m . -e hex /bricks/brick2/b1/f5
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b1/f5
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.gfid=0xce0a9956928e40afb78e95f78defd64f
    trusted.gfid2path.9cde09916eabc845=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6635
    
Selecting the file with latest mtime as source

This method is useful for per file healing and if you want the file with latest mtime has to be considered as source.

  1. Run the following command to obtain the list of files that are in split-brain:
    # gluster volume heal VOLNAME info split-brain
    From the output, identify the files for which file operations performed from the client failed with input/output error.
    For example,
    # gluster volume heal 12 info split-brain
    Brick 10.70.47.45:/bricks/brick2/b0
    /f4
    / - Is in split-brain
    
    Status: Connected
    Number of entries: 2
    
    Brick 10.70.47.144:/bricks/brick2/b1
    /f4
    / - Is in split-brain
    
    Status: Connected
    Number of entries: 2
    
    In the above command, 12 is the volume name, b0 and b1 are the bricks.
  2. The below command executed from backend provides information if a file is in GFID split-brain.
    # getfattr -d -e hex -m. <path-to-file>
    For example,
    On brick /b0
    
    # getfattr -d -m . -e hex /bricks/brick2/b0/f4
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b0/f4
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.afr.12-client-1=0x000000020000000100000000
    trusted.afr.dirty=0x000000000000000000000000
    trusted.gfid=0xb66b66d07b315f3c9cffac2fb6422a28
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
    
    
    On brick /b1
    
    # getfattr -d -m . -e hex /bricks/brick2/b1/f4
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b1/f4
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.afr.12-client-0=0x000000020000000100000000
    trusted.afr.dirty=0x000000000000000000000000
    trusted.gfid=0x87242f808c6e56a007ef7d49d197acff
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
    You can notice the difference in GFID for the file f4 in both the bricks.
    You can find the difference in the modify time by executing statcommand on the file from the bricks. The following is the output of the file f4 in bricks b0 and b1:
    On brick /b0
    
    # stat /bricks/brick2/b0/f4
    File: ‘/bricks/brick2/b0/f4’
    Size: 14            Blocks: 8          IO Block: 4096   regular file
    Device: fd15h/64789d    Inode: 67113349    Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: system_u:object_r:glusterd_brick_t:s0
    Access: 2018-08-29 20:57:38.913629991 +0530
    Modify: 2018-08-29 20:57:38.921630122 +0530
    Change: 2018-08-29 20:57:38.923630154 +0530
    Birth: -
    
    
    
    On brick /b1
    
    # stat /bricks/brick2/b1/f4
    File: ‘/bricks/brick2/b1/f4’
    Size: 2             Blocks: 8          IO Block: 4096   regular file
    Device: fd15h/64789d    Inode: 67111749    Links: 2
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: system_u:object_r:glusterd_brick_t:s0
    Access: 2018-08-24 20:54:50.953217256 +0530
    Modify: 2018-08-24 20:54:50.961217385 +0530
    Change: 2018-08-24 20:54:50.962217402 +0530
    Birth: -
    
  3. Execute the following command:
    # gluster volume healVOLNAME split-brain latest-mtime FILE 
    For example,
    # gluster volume heal 12 split-brain latest-mtime /f4
    GFID split-brain resolved for file /f4
    
    After the healing is complete, the GFID of the files on both bricks must be same. The following is a sample output of the getfattr command after completion of healing the file. You can notice that the file has been healed using the brick having the latest mtime as the source.
    On brick /b0
    
    # getfattr -d -m . -e hex /bricks/brick2/b0/f4
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b0/f4
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.gfid=0xb66b66d07b315f3c9cffac2fb6422a28
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
    
    
    On brick /b1
    
    # getfattr -d -m . -e hex /bricks/brick2/b1/f4
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b1/f4
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.gfid=0xb66b66d07b315f3c9cffac2fb6422a28
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
Selecting one replica as source for a particular file

This method is useful if you know which file is to be considered as source.

  1. Run the following command to obtain the list of files that are in split-brain:
    # gluster volume heal VOLNAME info split-brain
    From the output, identify the files for which file operations performed from the client failed with input/output error.
    For example,
    # gluster volume heal 12 info split-brain
    Brick 10.70.47.45:/bricks/brick2/b0
    /f3
    / - Is in split-brain
    
    Status: Connected
    Number of entries: 2
    
    Brick 10.70.47.144:/bricks/brick2/b1
    /f3
    / - Is in split-brain
    
    Status: Connected
    Number of entries: 2
    
    In the above command, 12 is the volume name, b0 and b1 are the bricks.

    Note

    With one replica as source option, there is no way to resolve all the GFID split-brain in one shot by not specifying any file-path in the CLI as done for data/metadata split-brain resolutions.
    For each file in GFID split-brain, you have to run the heal command separately.
  2. The below command executed from backend provides information if a file is in GFID split-brain.
     # getfattr -d -e hex -m. <path-to-file>
    For example,
    # getfattr -d -m . -e hex /bricks/brick2/b0/f3
    On brick /b0
    
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b0/f3
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.afr.12-client-1=0x000000020000000100000000
    trusted.afr.dirty=0x000000000000000000000000
    trusted.gfid=0x9d542fb1b3b15837a2f7f9dcdf5d6ee8
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
    
    On brick /b1
    
    # getfattr -d -m . -e hex /bricks/brick2/b1/f3
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b0/f3
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.afr.12-client-1=0x000000020000000100000000
    trusted.afr.dirty=0x000000000000000000000000
    trusted.gfid=0xc90d9b0f65f6530b95b9f3f8334033df
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
    You can notice the difference in GFID for the file f3 in both the bricks.
  3. Execute the following command:
    # gluster volume heal VOLNAME split-brain source-brick HOSTNAME : export-directory-absolute-path FILE
    In this command, FILE present in HOSTNAME : export-directory-absolute-path is taken as source for healing.
    For example,
    # gluster volume heal 12 split-brain source-brick 10.70.47.144:/bricks/brick2/b1 /f3
    GFID split-brain resolved for file /f3
    
    After the healing is complete, the GFID of the file on both the bricks should be same as that of the file which had bigger size. The following is a sample output of the getfattr command after the file is healed.
    On brick /b0
    
    # getfattr -d -m . -e hex /bricks/brick2/b0/f3
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b0/f3
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.gfid=0x90d9b0f65f6530b95b9f3f8334033df
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
    
    
    On brick /b1
    
    # getfattr -d -m . -e hex /bricks/brick2/b1/f3
    getfattr: Removing leading '/' from absolute path names
    # file: bricks/brick2/b1/f3
    security.selinux=0x73797374656d5f753a6f626a6563745f723a676c7573746572645f627269636b5f743a733000
    trusted.gfid=0x90d9b0f65f6530b95b9f3f8334033df
    trusted.gfid2path.364f55367c7bd6f4=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f6634
    
    

    Note

    You can not use the GFID of the file as an argument with any of the CLI options to resolve GFID split-brain. It should be the absolute path as seen from the mount point to the file considered as source.
    With source-brick option there is no way to resolve all the GFID split-brain in one shot by not specifying any file-path in the CLI as done while resolving data or metadata split-brain. For each file in GFID split-brain, run the CLI with the policy you want to use.
    Resolving directory GFID split-brain using CLI with the "source-brick" option in a "distributed-replicated" volume needs to be done on all the volumes explicitly. Since directories get created on all the subvolumes, using one particular brick as source for directory GFID split-brain, heal the directories for that subvolume. In this case, other subvolumes must be healed using the brick which has same GFID as that of the previous brick which was used as source for healing other subvolume. For information on resolving entry/type-mismatch split-brain, see Chapter 23, Manually Recovering File Split-brain .

11.15.4. Triggering Self-Healing on Replicated Volumes

For replicated volumes, when a brick goes offline and comes back online, self-healing is required to re-sync all the replicas. There is a self-heal daemon which runs in the background, and automatically initiates self-healing every 10 minutes on any files which require healing.
Multithreaded Self-heal

Self-heal daemon has the capability to handle multiple heals in parallel and is supported on Replicate and Distribute-replicate volumes. However, increasing the number of heals has impact on I/O performance so the following options have been provided. The cluster.shd-max-threads volume option controls the number of entries that can be self healed in parallel on each replica by self-heal daemon using. Using cluster.shd-wait-qlength volume option, you can configure the number of entries that must be kept in the queue for self-heal daemon threads to take up as soon as any of the threads are free to heal.

For more information on cluster.shd-max-threads and cluster.shd-wait-qlength volume set options, see Section 11.1, “Configuring Volume Options”.
There are various commands that can be used to check the healing status of volumes and files, or to manually initiate healing:
  • To view the list of files that need healing:
    # gluster volume heal VOLNAME info
    For example, to view the list of files on test-volume that need healing:
    # gluster volume heal test-volume info
    Brick server1:/gfs/test-volume_0
    Number of entries: 0
    
    Brick server2:/gfs/test-volume_1
    /95.txt
    /32.txt
    /66.txt
    /35.txt
    /18.txt
    /26.txt - Possibly undergoing heal
    /47.txt
    /55.txt
    /85.txt - Possibly undergoing heal
    ...
    Number of entries: 101
  • To trigger self-healing only on the files which require healing:
    # gluster volume heal VOLNAME
    For example, to trigger self-healing on files which require healing on test-volume:
    # gluster volume heal test-volume
    Heal operation on volume test-volume has been successful
  • To trigger self-healing on all the files on a volume:
    # gluster volume heal VOLNAME full
    For example, to trigger self-heal on all the files on test-volume:
    # gluster volume heal test-volume full
    Heal operation on volume test-volume has been successful
  • To view the list of files on a volume that are in a split-brain state:
    # gluster volume heal VOLNAME info split-brain
    For example, to view the list of files on test-volume that are in a split-brain state:
    # gluster volume heal test-volume info split-brain
    Brick server1:/gfs/test-volume_2
    Number of entries: 12
    at                   path on brick
    ----------------------------------
    2012-06-13 04:02:05  /dir/file.83
    2012-06-13 04:02:05  /dir/file.28
    2012-06-13 04:02:05  /dir/file.69
    Brick server2:/gfs/test-volume_2
    Number of entries: 12
    at                   path on brick
    ----------------------------------
    2012-06-13 04:02:05  /dir/file.83
    2012-06-13 04:02:05  /dir/file.28
    2012-06-13 04:02:05  /dir/file.69
    ...

11.17. Consistent time attributes within Replica and Disperse subvolumes

Traditionally, gluster has been using time attributes (ctime, atime, mtime) of files or directories from bricks. The problem with this approach is that it is not consistent across replicas and bricks, which are hosted by different nodes. Applications which depend on such timestamp attributes break as time attributes are not necessarily returned from the same brick of a replica set always.
One way to solve this issue would have been to allow gluster serve the stat structures from the same brick from a replica set and max-time in DHT.However, this still does not avoid the problem completely as there is no way to change ctime at the moment using the system call (lutimes() only allows mtime and atime). That would mean consistent ctime can not be maintained across replica bricks after self-heal, internal xattr updates and rebalance.
Hence, the solution is to store time attributes (ctime, mtime and atime) as an xattr(extended attribute) of the file. The xattr is updated based on the file operations. If a filesystem file operation changes only the mtime and ctime, gluster updates only these attributes in xattr for that file, which is maintained consistently on all backend bricks of a replica set.

11.17.1. Pre-requisites

Time must be synchronized between all client nodes. Red Hat recommends setting up a network time protocol service to keep time synchronized between all client nodes, and avoid inconsistent time attributes. See Network Time Protocol Setup

11.17.2. Enabling and disabling the Consistent Time Feature

The consistent time feature is disabled by default.
To enable the ctime feature for a specified volume, execute the following command:
# gluster volume set VOLNAME ctime on
To disable the ctime feature for a specified volume, execute the following command:
# gluster volume set VOLNAME ctime off

11.17.3. Advantages of Consistent Time Feature

Several applications like tar and elastic search give “file changed as we read it” and “Underlying file changed by an external force” warnings whenever it detects ctime differences if stat is served from different bricks. With consistent time feature enabled, these applications no longer throw the warnings as time attributes are served from extended attributes which are consistent across replica bricks.

11.17.4. Extended Attribute Format

The extended attribute used to store the time attributes is as below.
glusterfs.mdata = “<version – 8bits> <flags – 64bits> <ctime sec – 64bits> <ctime nsec – 64bits> <mtime sec - 64 bits> <mtime nsec-64 bits> <atime sec - 64 bits> <atime nsec - 64 bits>”
Example:
trusted.glusterfs.mdata=0x010000000000000000000000005cefab7b000000002bcb2587000000005cefab7b000000002bcb2587000000005cefab7b000000002b73964d

11.17.5. Upgrade

The older files (created before upgrade, where ctime feature is either not available or enabled) would not have “trusted.glusterfs.mdata” (stores consistent time attributes on all replica set) xattr created. The xattr gets created on first lookup on the file after upgrade or post enablement of this feature. Note that the xattr creation has to be driven from client and not from server to get consistent time attributes.

11.17.6. Limitations

  1. The access time (atime) updates are not supported. The support can be enabled by setting the “ctime.noatime” option to “off”. But enabling it would cause significant performance drop. The replicated and dispersed volume reads data from one subvolume resulting in the xattr update on that subvolume and triggering self heal for other subvolumes of replica set for each atime update.
  2. Mounting gluster volume with time attribute options (noatime, realatime) is not supported with this feature.
  3. This feature does not guarantee consistent time for directories if the hashed sub-volume for the directory is down.
  4. Directory listing may report inconsistent time information, hence this feature is not supported for workloads relying too much on directory listing or metadata.

Chapter 12. Managing Red Hat Gluster Storage Logs

The log management framework generates log messages for each of the administrative functionalities and the components to increase the user-serviceability aspect of Red Hat Gluster Storage Server. Logs are generated to track the event changes in the system. The feature makes the retrieval, rollover, and archival of log files easier and helps in troubleshooting errors that are user-resolvable. The Red Hat Gluster Storage Component logs are rotated on a weekly basis. Administrators can rotate a log file in a volume, as needed. When a log file is rotated, the contents of the current log file are moved to log-file-name.epoch-time-stamp.The components for which the log messages are generated with message-ids are glusterFS Management Service, Distributed Hash Table (DHT), and Automatic File Replication (AFR).

12.1. Log Rotation

Log files are rotated on a weekly basis and the log files are zipped in the gzip format on a fortnightly basis. When the content of the log file is rotated, the current log file is moved to log-file- name.epoch-time-stamp. The archival of the log files is defined in the configuration file. As a policy, log file content worth 52 weeks is retained in the Red Hat Gluster Storage Server.

12.2. Red Hat Gluster Storage Component Logs and Location

The table lists the component, services, and functionality based logs in the Red Hat Gluster Storage Server. As per the File System Hierarchy Standards (FHS) all the log files are placed in the /var/log directory.

Table 12.1. 

Component/Service Name Location of the Log File Remarks
glusterd /var/log/glusterfs/glusterd.log One glusterd log file per server. This log file also contains the snapshot and user logs.
gluster commands /var/log/glusterfs/cmd_history.log Gluster commands executed on a node in a Red Hat Gluster Storage Trusted Storage Pool is logged in this file.
bricks /var/log/glusterfs/bricks/<path extraction of brick path>.log One log file per brick on the server
rebalance /var/log/glusterfs/VOLNAME-rebalance.log One log file per volume on the server
self heal deamon /var/log/glusterfs/glustershd.log One log file per server
quota (Deprecated)
  • /var/log/glusterfs/quotad.log Log of the quota daemons running on each node.
  • /var/log/glusterfs/quota-crawl.log Whenever quota is enabled, a file system crawl is performed and the corresponding log is stored in this file
  • /var/log/glusterfs/quota-mount-VOLNAME.log An auxiliary FUSE client is mounted in <gluster-run-dir>/VOLNAME of the glusterFS and the corresponding client logs found in this file.
One log file per server (and per volume from quota-mount.
Gluster NFS (Deprecated) /var/log/glusterfs/nfs.log One log file per server
SAMBA Gluster /var/log/samba/glusterfs-VOLNAME-<ClientIP>.log If the client mounts this on a glusterFS server node, the actual log file or the mount point may not be found. In such a case, the mount outputs of all the glusterFS type mount operations need to be considered.
NFS - Ganesha/var/log/ganesha/ganesha.log, /var/log/ganesha/ganesha-gfapi.logOne log file per server
FUSE Mount /var/log/ glusterfs/<mountpoint path extraction>.log  
Geo-replication /var/log/glusterfs/geo-replication/<master> /var/log/glusterfs/geo-replication-slaves  
gluster volume heal VOLNAME info command /var/log/glusterfs/glfsheal-VOLNAME.log One log file per server on which the command is executed.
SwiftKrbAuth (Deprecated) /var/log/httpd/error_log  
Command Line Interface logs /var/log/glusterfs/cli.log This file captures log entries for every command that is executed on the Command Line Interface(CLI).

12.3. Configuring the Log Format

You can configure the Red Hat Gluster Storage Server to generate log messages either with message IDs or without them.
To know more about these options, see topic Configuring Volume Options in the Red Hat Gluster Storage Administration Guide.
To configure the log-format for bricks of a volume:
# gluster volume set VOLNAME diagnostics.brick-log-format <value>

Example 12.1. Generate log files with with-msg-id:

# gluster volume set testvol diagnostics.brick-log-format with-msg-id

Example 12.2. Generate log files with no-msg-id:

# gluster volume set testvol diagnostics.brick-log-format no-msg-id
To configure the log-format for clients of a volume:
gluster volume set VOLNAME diagnostics.client-log-format <value>

Example 12.3. Generate log files with with-msg-id:

# gluster volume set testvol diagnostics.client-log-format with-msg-id

Example 12.4. Generate log files with no-msg-id:

# gluster volume set testvol diagnostics.client-log-format no-msg-id
To configure the log format for glusterd:
# glusterd --log-format=<value>

Example 12.5. Generate log files with with-msg-id:

# glusterd --log-format=with-msg-id

Example 12.6. Generate log files with no-msg-id:

# glusterd --log-format=no-msg-id

12.4. Configuring the Log Level

Every log message has a log level associated with it. The levels, in descending order, are CRITICAL, ERROR, WARNING, INFO, DEBUG, and TRACE. Red Hat Gluster Storage can be configured to generate log messages only for certain log levels. Only those messages that have log levels above or equal to the configured log level are logged.
For example, if the log level is set to INFO, only CRITICAL, ERROR, WARNING, and INFO messages are logged.
The components can be configured to log at one of the following levels:
  • CRITICAL
  • ERROR
  • WARNING
  • INFO
  • DEBUG
  • TRACE

Important

Setting the log level to TRACE or DEBUG generates a very large number of log messages and can lead to disks running out of space very quickly.
To configure the log level on bricks
# gluster volume set VOLNAME diagnostics.brick-log-level <value>

Example 12.7. Set the log level to warning on a brick

# gluster volume set testvol diagnostics.brick-log-level WARNING
To configure the syslog level on bricks
# gluster volume set VOLNAME diagnostics.brick-sys-log-level <value>

Example 12.8. Set the syslog level to warning on a brick

# gluster volume set testvol diagnostics.brick-sys-log-level WARNING
To configure the log level on clients
# gluster volume set VOLNAME diagnostics.client-log-level <value>

Example 12.9. Set the log level to error on a client

# gluster volume set testvol diagnostics.client-log-level ERROR
To configure the syslog level on clients
# gluster volume set VOLNAME diagnostics.client-sys-log-level <value>

Example 12.10. Set the syslog level to error on a client

# gluster volume set testvol diagnostics.client-sys-log-level ERROR
To configure the log level for glusterd persistently
Edit the /etc/sysconfig/glusterd file, and set the value of the LOG_LEVEL parameter to the log level that you want glusterd to use.
## Set custom log file and log level (below are defaults)
#LOG_FILE='/var/log/glusterfs/glusterd.log'
LOG_LEVEL='VALUE'
This change does not take effect until glusterd is started or restarted with the service or systemctl command.

Example 12.11. Set the log level to WARNING on glusterd

Run the following commands to set the log level to WARNING:
  1. Edit the glusterd service file:
    On Red Hat Enterprise 7(RHEL 7) and RHEL 8, the glusterd service file is available at /usr/lib/systemd/system/glusterd.service
    On RHEL 6, the glusterd service file is available at /etc/sysconfig/glusterd

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  2. Change the LOG_LEVEL variable to the required debug level.
    ## Set custom log file and log level (below are defaults)
                     #LOG_FILE='/var/log/glusterfs/glusterd.log'
                     LOG_LEVEL='WARNING'
  3. Reload the daemon:
    On RHEL 7 and RHEL 8, run
    systemctl daemon-reload
    On RHEL 6, run
    service glusterd reload

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  4. Restart the glusterd service.
    On RHEL 7 and RHEL 8, run
    systemctl restart glusterd
    On RHEL 6, run
    service glusterd restart

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide

Example 12.12. Run volume status with a log level of ERROR

# gluster --log-level=ERROR volume status

12.5. Suppressing Repetitive Log Messages

Repetitive log messages in the Red Hat Gluster Storage Server can be configured by setting a log-flush-timeout period and by defining a log-buf-size buffer size options with the gluster volume set command.
Suppressing Repetitive Log Messages with a Timeout Period

To set the timeout period on the bricks:
# gluster volume set VOLNAME diagnostics.brick-log-flush-timeout <value in seconds>

Example 12.13. Set a timeout period on the bricks

# gluster volume set testvol diagnostics.brick-log-flush-timeout 200sec
volume set: success
To set the timeout period on the clients:
# gluster volume set VOLNAME diagnostics.client-log-flush-timeout <value in seconds>

Example 12.14. Set a timeout period on the clients

# gluster volume set testvol diagnostics.client-log-flush-timeout 180sec
volume set: success
To set the timeout period on glusterd:
# glusterd --log-flush-timeout=<value in seconds>

Example 12.15. Set a timeout period on the glusterd

# glusterd --log-flush-timeout=60sec
Suppressing Repetitive Log Messages by defining a Buffer Size

The maximum number of unique log messages that can be suppressed until the timeout or buffer overflow, whichever occurs first on the bricks.

To set the buffer size on the bricks:
# gluster volume set VOLNAME diagnostics.brick-log-buf-size <value>

Example 12.16. Set a buffer size on the bricks

# gluster volume set testvol diagnostics.brick-log-buf-size 10
volume set: success
To set the buffer size on the clients:
# gluster volume set VOLNAME diagnostics.client-log-buf-size <value>

Example 12.17. Set a buffer size on the clients

# gluster volume set testvol diagnostics.client-log-buf-size 15
volume set: success
To set the log buffer size on glusterd:
# glusterd --log-buf-size=<value>

Example 12.18. Set a log buffer size on the glusterd

# glusterd --log-buf-size=10

Note

To disable suppression of repetitive log messages, set the log-buf-size to zero.

12.6. Geo-replication Logs

The following log files are used for a geo-replication session:
  • Master-log-file - log file for the process that monitors the master volume.
  • Slave-log-file - log file for process that initiates changes on a slave.
  • Master-gluster-log-file - log file for the maintenance mount point that the geo-replication module uses to monitor the master volume.
  • Slave-gluster-log-file - If the slave is a Red Hat Gluster Storage Volume, this log file is the slave's counterpart of Master-gluster-log-file.

12.6.1. Viewing the Geo-replication Master Log Files

To view the Master-log-file for geo-replication, use the following command:
# gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config log-file
For example:
# gluster volume geo-replication Volume1 example.com::slave-vol config log-file

12.6.2. Viewing the Geo-replication Slave Log Files

To view the log file for geo-replication on a slave, use the following procedure. glusterd must be running on slave machine.
  1. On the master, run the following command to display the session-owner details:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config session-owner
    For example:
    # gluster volume geo-replication Volume1 example.com::slave-vol config session-owner 5f6e5200-756f-11e0-a1f0-0800200c9a66
  2. On the slave, run the following command with the session-owner value from the previous step:
    # gluster volume geo-replication SLAVE_VOL config log-file /var/log/gluster/SESSION_OWNER:remote-mirror.log 
    For example:
    # gluster volume geo-replication slave-vol config log-file /var/log/gluster/5f6e5200-756f-11e0-a1f0-0800200c9a66:remote-mirror.log

Chapter 13. Managing Red Hat Gluster Storage Volume Life-Cycle Extensions

Red Hat Gluster Storage allows automation of operations by user-written scripts. For every operation, you can execute a pre and a post script.
Pre Scripts: These scripts are run before the occurrence of the event. You can write a script to automate activities like managing system-wide services. For example, you can write a script to stop exporting the SMB share corresponding to the volume before you stop the volume.
Post Scripts: These scripts are run after execution of the event. For example, you can write a script to export the SMB share corresponding to the volume after you start the volume.
You can run scripts for the following events:
  • Creating a volume
  • Starting a volume
  • Adding a brick
  • Removing a brick
  • Tuning volume options
  • Stopping a volume
  • Deleting a volume
Naming Convention
While creating the file names of your scripts, you must follow the naming convention followed in your underlying file system like XFS.

Note

To enable the script, the name of the script must start with an S . Scripts run in lexicographic order of their names.

13.1. Location of Scripts

This section provides information on the folders where the scripts must be placed. When you create a trusted storage pool, the following directories are created:
  • /var/lib/glusterd/hooks/1/create/
  • /var/lib/glusterd/hooks/1/delete/
  • /var/lib/glusterd/hooks/1/start/
  • /var/lib/glusterd/hooks/1/stop/
  • /var/lib/glusterd/hooks/1/set/
  • /var/lib/glusterd/hooks/1/add-brick/
  • /var/lib/glusterd/hooks/1/remove-brick/
After creating a script, you must ensure to save the script in its respective folder on all the nodes of the trusted storage pool. The location of the script dictates whether the script must be executed before or after an event. Scripts are provided with the command line argument --volname=VOLNAME to specify the volume. Command-specific additional arguments are provided for the following volume operations:
  • Start volume
    • --first=yes, if the volume is the first to be started
    • --first=no, for otherwise
  • Stop volume
    • --last=yes, if the volume is to be stopped last.
    • --last=no, for otherwise
  • Set volume
    • -o key=value
      For every key, value is specified in volume set command.

13.2. Prepackaged Scripts

Red Hat provides scripts to export Samba (SMB) share when you start a volume and to remove the share when you stop the volume. These scripts are available at: /var/lib/glusterd/hooks/1/start/post and /var/lib/glusterd/hooks/1/stop/pre. By default, the scripts are enabled.
When you start a volume using the following command:
# gluster volume start VOLNAME
The S30samba-start.sh script performs the following:
  1. Adds Samba share configuration details of the volume to the smb.conf file
  2. Mounts the volume through FUSE and adds an entry in /etc/fstab for the same.
  3. Restarts Samba to run with updated configuration
When you stop the volume using the following command:
# gluster volume stop VOLNAME
The S30samba-stop.sh script performs the following:
  1. Removes the Samba share details of the volume from the smb.conf file
  2. Unmounts the FUSE mount point and removes the corresponding entry in /etc/fstab
  3. Restarts Samba to run with updated configuration

Chapter 14. Detecting BitRot

BitRot detection is a technique used in Red Hat Gluster Storage to identify when silent corruption of data has occurred. BitRot also helps to identify when a brick's data has been manipulated directly, without using FUSE, NFS or any other access protocols. BitRot detection is particularly useful when using JBOD, since JBOD does not provide other methods of determining when data on a disk has become corrupt.
The gluster volume bitrot command scans all the bricks in a volume for BitRot issues in a process known as scrubbing. The process calculates the checksum for each file or object, and compares that checksum against the actual data of the file. When BitRot is detected in a file, that file is marked as corrupted, and the detected errors are logged in the following files:
  • /var/log/glusterfs/bitd.log
  • /var/log/glusterfs/scrub.log

14.1. Enabling and Disabling the BitRot daemon

The BitRot daemon is disabled by default. In order to use or configure the daemon, you first need to enable it.
gluster volume bitrot VOLNAME enable
Enable the BitRot daemon for the specified volume.
gluster volume bitrot VOLNAME disable
Disable the BitRot daemon for the specified volume.

14.2. Modifying BitRot Detection Behavior

Once the daemon is enabled, you can pause and resume the detection process, check its status, and modify how often or how quickly it runs.
gluster volume bitrot VOLNAME scrub ondemand
Starts the scrubbing process and the scrubber will start crawling the file system immediately. Ensure to keep the scrubber in 'Active (Idle)' state, where the scrubber is waiting for it's next frequency cycle to start scrubbing, for on demand scrubbing to be successful. On demand scrubbing does not work when the scrubber is in 'Paused' state or already running.
gluster volume bitrot VOLNAME scrub pause
Pauses the scrubbing process on the specified volume. Note that this does not stop the BitRot daemon; it stops the process that cycles through the volume checking files.
gluster volume bitrot VOLNAME scrub resume
Resumes the scrubbing process on the specified volume. Note that this does not start the BitRot daemon; it restarts the process that cycles through the volume checking files.
gluster volume bitrot VOLNAME scrub status
This command prints a summary of scrub status on the specified volume, including various configuration details and the location of the bitrot and scrubber error logs for this volume. It also prints details each node scanned for errors, along with identifiers for any corrupted objects located.
gluster volume bitrot VOLNAME scrub-throttle rate
Because the BitRot daemon scrubs the entire file system, scrubbing can have a severe performance impact. This command changes the rate at which files and objects are verified. Valid rates are lazy, normal, and aggressive. By default, the scrubber process is started in lazy mode.
gluster volume bitrot VOLNAME scrub-frequency frequency
This command changes how often the scrub operation runs when the BitRot daemon is enabled. Valid options are daily, weekly, biweekly, and monthly.By default, the scrubber process is set to run biweekly.

14.3. Restoring a bad file

When bad files are revealed by the scrubber, you can perform the following process to heal the file by recovering a copy from a replicate volume.

Important

The following procedure is easier if GFID-to-path translation is enabled.
Mount all volumes using the -oaux-gfid-mount mount option, and enable GFID-to-path translation on each volume by running the following command.
# gluster volume set VOLNAME build-pgfid on
Files created before this option was enabled must be looked up with the find command.

Procedure 14.1. Restoring a bad file from a replicate volume

  1. Note the identifiers of bad files

    Check the output of the scrub status command to determine the identifiers of corrupted files.
    # gluster volume bitrot VOLNAME scrub status
    Volume name: VOLNAME
    ...
    Node name: NODENAME
    ...
    Error count: 3
    Corrupted objects:
    5f61ade8-49fb-4c37-af84-c95041ff4bf5
    e8561c6b-f881-499b-808b-7fa2bce190f7
    eff2433f-eae9-48ba-bdef-839603c9434c
  2. Determine the path of each corrupted object

    For files created after GFID-to-path translation was enabled, use the getfattr command to determine the path of the corrupted files.
    # getfattr -n glusterfs.ancestry.path -e text
    /mnt/VOLNAME/.gfid/GFID
    ...
    glusterfs.ancestry.path="/path/to/corrupted_file"
    For files created before GFID-to-path translation was enabled, use the find command to determine the path of the corrupted file and the index file that match the identifying GFID.
    # find /rhgs/brick*/.glusterfs -name GFID
    /rhgs/brick1/.glusterfs/path/to/GFID
    # find /rhgs -samefile /rhgs/brick1/.glusterfs/path/to/GFID
    /rhgs/brick1/.glusterfs/path/to/GFID
    /rhgs/brick1/path/to/corrupted_file
  3. Delete the corrupted files

    Delete the corrupted files from the path output by the getfattr or find command.
  4. Delete the GFID file

    Delete the GFID file from the /rhgs/brickN/.glusterfs directory.
  5. Restore the file

    Follow these steps to safely restore corrupt files.
    1. Disable metadata caching

      If the metadata cache is enabled, disable it by running the following command:
      # gluster volume set VOLNAME stat-prefetch off
    2. Create a recovery mount point

      Create a mount point to use for the recovery process. For example, /mnt/recovery.
      # mkdir /mnt/recovery
    3. Mount the volume with timeouts disabled

      # mount -t glusterfs -o attribute-timeout=0,entry-timeout=0 hostname:volume-path /mnt/recovery
    4. Heal files and hard links

      Access files and hard links to heal them. For example, run the stat command on the files and hard links you need to heal.
      $ stat /mnt/recovery/corrupt-file
      If you do not have client self-heal enabled, you must manually heal the volume with the following command.
      # gluster volume heal VOLNAME
    5. Unmount and optionally remove the recovery mount point

      # umount /mnt/recovery
      # rmdir /mnt/recovery
    6. Optional: Re-enable metadata caching

      If the metadata cache was enabled previously, re-enable it by running the following command:
      # gluster volume set VOLNAME stat-prefetch on
The next time that the bitrot scrubber runs, this GFID is no longer listed (unless it has become corrupted again).

Chapter 15. Incremental Backup Assistance using Glusterfind

Glusterfind is a utility that provides the list of files that are modified between the previous backup session and the current period. The commands can be executed at regular intervals to retrieve the list. Multiple sessions for the same volume can be present for different use cases. The changes that are recorded are, new file/directories, data/metadata modifications, rename, and deletes.

15.1. Glusterfind Configuration Options

The following is the list configuration options available in Glusterfind:
  • Glusterfind Create
  • Glusterfind Pre
  • Glusterfind Post
  • Glusterfind Query
  • Glusterfind List
  • Glusterfind Delete

Note

All the glusterfind configuration commands such as, glusterfind pre, glusterfind post, glusterfind list, and glusterfind delete for a session have to be executed only on the node on which session is created.
Glusterfind Create

To create a session for a particular instance in the volume, execute the following command:

# glusterfind create [-h] [--debug] [--force] <SessionName> <volname> [--reset-session-time]
where,
--force: is executed when a new node/brick is added to the volume .
--reset-session-time: forces reset of the session time. The next incremental run will start from this time.
--help OR -h: Used to display help for the command.
SessionName: Unique name of a session.
volname: Name of the volume for which the create command is executed.
For example:
# glusterfind create sess_vol1 vol1
Session sess_vol1 created with volume vol1
Glusterfind Pre

Ensure that all nodes are online before glusterfind Pre operation. To retrieve the list of modified files and directories and store it in the outfile, execute the following command:

# glusterfind pre [-h] [--debug] [--no-encode] [--full] [--disable-partial] [--output-prefix OUTPUT_PREFIX] [--regenerate-outfile] [-N] [--tag-for-full-find TAG_FOR_FULL_FIND] [--type {f,d,both}] [--field-separator FIELD_SEPARATOR] <session> <volname> <outfile>
where,
--help OR -h: Displays help for the command
--debug: Enables the debug mode
--no-encode: The file paths are encoded by default in the output file. This option disables encoding of file paths.
--full: Performs a full search.
--disable-partial: Disables the partial-find feature that is enabled by default.
--output-prefix OUTPUT_PREFIX: Prefix to the path/name that is specified in the outfile.
--regenerate-outfile: Regenerates a new outfile and discards the outfile generated from the last pre command.
-N OR --only-namespace-changes: List only namespace changes
--tag-for-full-find TAG_FOR_FULL_FIND: Tag prefix for file names emitted during a full find operation. Default value is NEW
--type {f,d,both}: type: f, f-files only ; d, d-directories only ; by default = both
--field-separator: Specifies the character/s that glusterfind output uses to separate fields. By default this is a single space, but if your file names contain spaces, you may want to change the delimiter so you can parse the output of glusterfind automatically.
session: Unique name of a session.
volname: Name of the volume for which the pre command is executed.
outfile: Incremental list of modified files.
For example:
# glusterfind pre sess_vol1 vol1 /tmp/outfile.txt
Generated output file /tmp/outfile.txt

Note

The output format is <TYPE> <PATH1> <PATH2>. Possible type values are, NEW, MODIFY, DELETE and RENAME. PATH2 is applicable only if type is RENAME. For example:
NEW file1
NEW dir1%2Ffile2
MODIFY dir3%2Fdir4%2Ftest3
RENAME test1 dir1%2F%2Ftest1new
DELETE test2
The example output with --no-encode option
NEW file1
NEW dir1/file2
MODIFY dir3/dir4/test3
RENAME test1 dir1/test1new
DELETE test2
Glusterfind Post

The following command is run to update the session time:

# glusterfind post [-h] [--debug] <SessionName> <volname>
where,
SessionName: Unique name of a session.
volname: Name of the volume for which the post command is executed.
For example:
# glusterfind post sess_vol1 vol1
Session sess_vol1 with volume vol1 updated
Glusterfind List

To list all the active sessions and the corresponding volumes present in the cluster, execute the following command:

# glusterfind list [-h] [--session SESSION] [--volume VOLUME] [--debug]
where,
--session SESSION: Displays the information related to that session
--volume VOLUME: Displays all the active sessions corresponding to that volume
--help OR -h: Displays help for the command
For example:
# glusterfind list
SESSION VOLUME SESSION TIME
--------------------------------------------------
sess_vol1 vol1 2015-06-22 22:22:53
Glusterfind Query

The glusterfind query subcommand provides a list of changed files based on a specified time stamp. These commands do not check any change log information. Use the glusterfind query subcommand when your backup software maintains its own checkpoints and time stamps outside glusterfind. The glusterfind query subcommand can be used as follows:

# glusterfind query [-h] [--since-time SINCE_TIME] [--end-time END_TIME] [--no-encode] [--full] [--debug] [--disable-partial] [--output-prefix OUTPUT_PREFIX] [-N] [--tag-for-full-find TAG_FOR_FULL_FIND] [--type {f,d,both}] [--field-separator FIELD_SEPARATOR] volname outfile
where,
--help OR -h: Displays help for the command
--since-time SINCE_TIME: Start time stamp expected in seconds, since the Linux epoch date (1970-01-01 00:00:00 UTC). Current Linux epoch time can be determined by executing echo $(date +'%s') command.
--end-time END_TIME: End time stamp expected in seconds, since the Linux epoch date (1970-01-01 00:00:00 UTC). Current Linux epoch time can be determined by executing echo $(date +'%s') command.
--no-encode: The file paths are encoded by default in the output file. This option disables encoding of file paths.
--full: Performs a full search. This cannot be used with --since-time and --end-time.
--debug: Enables the debug mode.
--disable-partial: Disables the partial-find feature that is enabled by default.
--output-prefix OUTPUT_PREFIX: Prefix to the path/name that is specified in the outfile.
-N OR --only-namespace-changes: List only namespace changes
--tag-for-full-find TAG_FOR_FULL_FIND: Tag prefix for file names emitted during a full find operation. Default value is NEW
--type {f,d,both}: type: f, f-files only ; d, d-directories only ; by default = both
--field-separator: Specifies the character/s that glusterfind output uses to separate fields. By default this is a single space, but if your file names contain spaces, you may want to change the delimiter so you can parse the output of glusterfind automatically.
volname: Name of the volume for which the pre command is executed.
outfile: Incremental list of modified files.
For example:
To retrieve files changed between two timestamps, run the following command:
# glusterfind query volname --since-time timestamp1 --end-time timestamp2 output_file.txt
Time stamps are expected in seconds since the Linux epoch date (1970-01-01 00:00:00 UTC). Current Linux epoch time can be output by running echo $(date +'%s') on the command line.
You can retrieve all files in the volume by running the following command:
# glusterfind query volname --full output_file.txt
When running a full find operation, you can also retrieve a subset of files according to a tag. For example, to find all new files on a volume, run the following command:
# glusterfind query volname --full --tag-for-full-find NEW output_file.txt
By default, the output of glusterfind uses a single space to separate fields. If your file names contain spaces, you may want to change the delimiter in order to parse the output of glusterfind automatically. You can set the delimiter to one or more characters by using the --field-separator option. The following command sets the field separator to ==.
# gluster query volname --full output_file.txt --field-separator "=="
Glusterfind Delete

To clear out all the session information associated with that particular session, execute the following command:

Ensure, no further backups are expected to be taken in a particular session.
# glusterfind delete [-h] [--debug] <SessionName> <volname>
where,
SessionName: Unique name of a session.
volname: Name of the volume for which the delete command is executed.
For example:
# glusterfind delete sess_vol1 vol1
Session sess_vol1 with volume vol1 deleted

15.1.1. Adding or Replacing a Brick from an Existing Glusterfind Session

When a new brick is added or an existing brick is replaced, execute the glusterfind create command with force for the existing session to work. For example:
# glusterfind create existing-session volname --force

Chapter 16. Managing Tiering (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
Tiering refers to automatic classification and movement of data based on the user I/O access. The tiering feature continuously monitors the workload, identifies hotspots by measuring and analysing the statistics of the activity, and moves frequently accessed data to the highest performance hot tier (such as solid state drives (SSDs)), and inactive data to the lower performing cold tier (such as spinning disks) all without I/O interruption. With tiering, data promotion and automatic rebalancing improve access time for popular files, while demoting infrequently accessed files to the cold tier regulates the hot tier's capacity.

Important

Data is moved, not copied, from one tier to another. When a file is moved to one tier, a copy is not kept on the other tier.
Tiering monitors and identifies the activity level of the data and automatically moves the active and inactive data to the most appropriate storage tier. Moving data between tiers of hot and cold storage is a computationally expensive task. To address this, Red Hat Gluster Storage supports automated promotion and demotion of data within a volume in the background so as to minimize impact on foreground I/O. Data becomes hot or cold based on the rate at which it is accessed. If access to a file increases, it moves to the hot tier or retains its place in the hot tier. If the file is not accessed for a while, it moves to the cold tier, or retains it place in the cold tier. Hence, the data movement can happen in either direction which is based totally on the access frequency.
Different sub-volume types act as hot and cold tiers and data is automatically assigned or reassigned a “temperature” based on the frequency of access. Red Hat Gluster Storage allows attaching fast performing disks as hot tier, uses the existing volume as cold tier, and these hot tier and cold tier forms a single tiered volume. For example, the existing volume may be distributed dispersed on HDDs and the hot tier could be distributed-replicated on SSDs.
Hot Tier

The hot tier is the tiering volume created using better performing subvolumes, an example of which could be SSDs. Frequently accessed data is placed in the highest performance and most expensive hot tier. Hot tier volume could be a distributed volume or distributed-replicated volume.

Warning

Distributed volumes can suffer significant data loss during a disk or server failure because directory contents are spread randomly across the bricks in the volume. Red Hat recommends creating distributed-replicated tier volume.
Cold Tier

The cold tier is the existing Red Hat Gluster Storage volume created using slower storage such as Spinning disks. Inactive or infrequently accessed data is placed in the lowest-cost cold tier.

Data Migration

Tiering automatically migrates files between hot tier and cold tier to improve the storage performance and resource use.

16.1. Tiering Architecture (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
Tiering provides better I/O performance as a subset of the data is stored in the hot tier. Tiering involves creating a pool of relatively fast/expensive storage devices (example, solid state drives) configured to act as a hot tier, and an existing volume which are relatively slower/cheaper devices configured to act as a cold tier. The tiering translator handles where to place the files and when to migrate files from the cold tier to the hot tier and vice versa.
The following diagrams illustrates how tiering works when attached to a distributed-dispersed volume. Here, the existing distributed-dispersed volume would become a cold-tier and the new fast/expensive storage device would act as a hot tier. Frequently accessed files will be migrated from cold tier to the hot tier for better performance.
Tiering Architecture

Figure 16.1. Tiering Architecture

16.2. Key Benefits of Tiering (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
The following are the key benefits of data tiering:
  • Automatic classification and movement of files based on the access patterns
  • Faster response time and reduced latency
  • Better I/O performance
  • Improved data-storage efficiency
  • Reduced deployment and operating costs

16.3. Tiering Limitations (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
The following limitations apply to the use Tiering feature:
  • Native client support for tiering is limited to Red Hat Enterprise Linux version 6.7, 6.8 and 7.x clients. Tiered volumes cannot be mounted by Red Hat Enterprise Linux 5.x clients.
  • Tiering works only with cache friendly workloads. Attaching a tier volume to a cache unfriendly workload will lead to slow performance. In a cache friendly workload, most of the reads and writes are accessing a subset of the total amount of data. And, this subset fits on the hot tier. This subset should change only infrequently.
  • Tiering feature is supported only on Red Hat Enterprise Linux 7 based Red Hat Gluster Storage. Tiering feature is not supported on Red Hat Enterprise Linux 6 based Red Hat Gluster Storage.
  • Only Fuse and gluster-nfs access is supported. Server Message Block (SMB) and nfs-ganesha access to tiered volume is not supported.
  • Creating snapshot of a tiered volume is supported. Snapshot clones are not supported with the tiered volumes.
  • When you run tier detach commit or tier detach force, ongoing I/O operations may fail with a Transport endpoint is not connected error.
  • Files with hardlinks and softlinks are not migrated.
  • Files on which POSIX locks has been taken are not migrated until all locks are released.
  • Add brick, remove brick, and rebalance operations are not supported on the tiered volume. For information on expanding a tiered volume, see Section 11.7.1, “Expanding a Tiered Volume” and for information on shrinking a tiered volume, see Section 11.8.2, “Shrinking a Tiered Volume ”

16.4. Attaching a Tier to a Volume (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
By default, tiering is not enabled on gluster volumes. An existing volume can be modified via a CLI command to have a hot tier. You must enable a volume by performing an attach tier operation. The attach command will declare an existing volume as cold tier and creates a new hot tier volume which is appended to it. Together, the combination is a single tiered volume.
It is highly recommended to provision your storage liberally and generously before attaching a tier. You create a normal volume and then attach bricks to it, which are the hot tier:
  1. Attach the tier to the volume by executing the following command:
    # gluster volume tier VOLNAME attach [replica COUNT] NEW-BRICK...
    For example,
    # gluster volume tier test-volume attach replica 3 server1:/rhgs/brick5/b1 server2:/rhgs/brick6/b2
    server1:/rhgs/brick7/b3 server2:/rhgs/brick8/b4
  2. Run gluster volume info command to optionally display the volume information.
    The command output displays information similar to the following:
    # gluster volume info test-volume
    Volume Name: test-volume
    Type: Tier
    Status: Started
    Number of Bricks: 8
    Transport-type: tcp
    Hot Tier :
    Hot Tier Type : Distributed-Replicate
    Number of Bricks: 2 x 2 = 4
    Brick1: server1:/rhgs/brick5/b1
    Brick2: server2:/rhgs/brick6/b2
    Brick3: server1:/rhgs/brick7/b3
    Brick4: server2:/rhgs/brick8/b4
    Cold Tier:
    Cold Tier Type : Distributed-Replicate
    Number of Bricks: 2 x 2 = 4
    Brick5: server1:/rhgs/brick1/b5
    Brick6: server2:/rhgs/brick2/b6
    Brick7: server1:/rhgs/brick3/b7
    Brick8: server2:/rhgs/brick4/b8
    Options Reconfigured:
    cluster.watermark-low: 70
    cluster.watermark-hi: 90
    cluster.tier-demote-frequency: 45
    cluster.tier-mode: cache
    features.ctr-enabled: on
    performance.readdir-ahead: on
The tier start command is triggered automatically after the tier has been attached. In some cases, if the tier process has not started you must start it manually using the gluster volume tier VOLNAME start force command.

16.4.1. Attaching a Tier to a Geo-replicated Volume (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
You can attach a tier volume to the master volume of the geo-replication session for better performance.

Important

A crash has been observed in the Slave mounts when performance.quick-read option is enabled and geo-replicated from a tiered master volume. If the master volume is a tiered volume, you must disable the performance.quick-read option in the Slave Volume using the following command:
# gluster volume set Slavevol performance.quick-read off
  1. Stop geo-replication between the master and slave, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop
    For example:
    # gluster volume geo-replication Volume1 example.com::slave-vol stop
  2. Attach the tier to the volume using the following command:
    # gluster volume tier VOLNAME attach [replica COUNT] NEW-BRICK...
    For example, to create a distributed-replicated tier volume with replica count two:
    # gluster volume tier test-volume attach replica 3 server1:/rhgs/brick1/b1 server2:/rhgs/brick2/b2
    server1:/rhgs/brick3/b3 server2:/rhgs/brick4/b4
  3. Restart the geo-replication sessions, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start
    For example
    # gluster volume geo-replication Volume1 example.com::slave-vol start
  4. Verify whether geo-replication session has started with tier's bricks, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status
    For example,
    # gluster volume geo-replication Volume1 example.com::slave-vol status

16.5. Configuring a Tiering Volume (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
Tiering volume has several configuration options. You may set tier volume configuration options with the following usage:
# gluster volume set VOLNAME key value

16.5.1. Configuring Watermarks (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
When the tier volume is configured to use the cache mode, the configured watermark values and the percentage of the hot tier that is full determine whether a file will be promoted or demoted. The cluster.watermark-low and cluster.watermark-hi volume options set the lower and upper watermark values respectively for a tier volume.
The promotion and demotion of files is determined by how full the hot tier is. Data accumulates on the hot tier until it reaches the low watermark, even if it is not accessed for a period of time. This prevents files from being demoted unnecessarily when there is plenty on free space on the hot tier. When the hot tier is fuller than the lower watermark but less than the high watermark, data is randomly promoted and demoted where the likelihood of promotion decreases as the tier becomes fuller; the opposite holds for demotion. If the hot tier is fuller than the high watermark, promotions stop and demotions happen more frequently in order to free up space.
The following diagram illustrates how cache mode works and the example values you can set.
Tiering Watermarks

Figure 16.2. Tiering Watermarks

To set the percentage for promotion and demotion of files, run the following commands:
# gluster volume set VOLNAME cluster.watermark-hi value
# gluster volume set VOLNAME cluster.watermark-low value

16.5.2. Configuring Promote and Demote Frequency (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
You can configure how frequently the files are to be checked for promotion and demotion of files. The check is based on whether the file was accessed or not in the last n seconds. If the promote/demote frequency is not set, then the default value for promote frequency is 120 seconds and demote frequency is 3600 seconds.
To set the frequency for the promotion and demotion of files, run the following command:
# gluster volume set VOLNAME cluster.tier-demote-frequency value_in_seconds
# gluster volume set VOLNAME cluster.tier-promote-frequency value_in_seconds

16.5.3. Configuring Read and Write Frequency (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
You can configure the number of reads and writes in a promotion/demotion cycle, that would mark a file HOT for promotion. Any file that has read or write hits less than this value will be considered as COLD and will be demoted. If the read/write access count is not set, then the default count is set to 0.
Set the read and write frequency threshold by executing the following command:
# gluster volume set VOLNAME cluster.write-freq-threshold value

Note

The value of 0 indicates that the threshold value is not considered. Any value in the range of 1-1000 denotes the number of times the contents of file must be modified to consider for promotion or demotion...
# gluster volume set VOLNAME cluster.read-freq-threshold value

Note

The value of 0 indicates that the threshold value is not considered. Any value in the range of 1-1000 denotes the number of times the contents of file contents have been accessed to consider for promotion or demotion.

16.5.4. Configuring Target Data Size (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
The maximum amount of data that may be migrated in any direction in one promotion/demotion cycle from each node can be configured using the following command:
# gluster volume set VOLNAME cluster.tier-max-mb value_in_mb
If the cluster.tier-max-mb count is not set, then the default data size is set to 4000 MB.

16.5.5. Configuring the File Count per Cycle (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
The maximum number of files that may be migrated in any direction in one promotion/demotion cycle from each node can be configured using the following command:
# gluster volume set VOLNAME cluster.tier-max-files count
If the cluster.tier-max-files count is not set, then the default count is set to 10000.

16.6. Displaying Tiering Status Information (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
The status command displays the tiering volume information.
# gluster volume tier VOLNAME status
For example,
# gluster volume tier test-volume status
Node                 Promoted files       Demoted files        Status
---------            ---------            ---------            ---------
localhost            1                    5                    in progress
server1              0                    2                    in progress
Tiering Migration Functionality: test-volume: success

16.7. Detaching a Tier from a Volume (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
To detach a tier, perform the following steps:
  1. Start the detach tier by executing the following command:
    # gluster volume tier VOLNAME detach start
    For example,
    # gluster volume tier test-volume detach start
  2. Monitor the status of detach tier until the status displays the status as complete.
    # gluster volume tier VOLNAME detach status
    For example,
    # gluster volume tier test-volume detach status
    Node Rebalanced-files          size       scanned      failures       skipped               status       run time in secs
    --------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
    localhost           0        0Bytes             0             0             0            completed               0.00
    server1             0        0Bytes             0             0             0            completed               1.00
    server2             0        0Bytes             0             0             0            completed               0.00
    server1             0        0Bytes             0             0             0            completed
    server2             0        0Bytes             0             0             0            completed

    Note

    It is possible that some files are not migrated to the cold tier on a detach operation for various reasons like POSIX locks being held on them. Check for files on the hot tier bricks and you can either manually move the files, or turn off applications (which would presumably unlock the files) and stop/start detach tier, to retry.
  3. When the tier is detached successfully as shown in the previous status command, run the following command to commit the tier detach:
    # gluster volume tier VOLNAME detach commit
    For example,
    # gluster volume tier test-volume detach commit
    Removing tier can result in data loss. Do you want to Continue? (y/n)
    y
    volume detach-tier commit: success
    Check the detached bricks to ensure all files are migrated.
    If files with data are found on the brick path, copy them via a gluster mount point before re-purposing the removed brick.

Note

When you run tier detach commit or tier detach force, ongoing I/O operations may fail with a Transport endpoint is not connected error.
After the detach tier commit is completed, you can verify that the volume is no longer a tier volume by running gluster volume info command.

16.7.1. Detaching a Tier of a Geo-replicated Volume (Deprecated)

Warning

Tiering is considered deprecated as of Red Hat Gluster Storage 3.5. Red Hat no longer recommends its use, and does not support tiering in new deployments and existing deployments that upgrade to Red Hat Gluster Storage 3.5.3.
  1. Start the detach tier by executing the following command:
    # gluster volume tier VOLNAME detach start
    For example,
    # gluster volume tier test-volume detach start
  2. Monitor the status of detach tier until the status displays the status as complete.
    # gluster volume tier VOLNAME detach status
    For example,
    # gluster volume tier test-volume detach status
    Node Rebalanced-files          size       scanned      failures       skipped               status       run time in secs
    --------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
    localhost           0        0Bytes             0             0             0            completed               0.00
    server1             0        0Bytes             0             0             0            completed               1.00
    server2             0        0Bytes             0             0             0            completed               0.00
    server1             0        0Bytes             0             0             0            completed
    server2             0        0Bytes             0             0             0            completed

    Note

    There could be some number of files that were not moved. Such files may have been locked by the user, and that prevented them from moving to the cold tier on the detach operation. You must check for such files. If you find any such files, you can either manually move the files, or turn off applications (which would presumably unlock the files) and stop/start detach tier, to retry.
  3. Set a checkpoint on a geo-replication session to ensure that all the data in that cold-tier is synced to the slave. For more information on geo-replication checkpoints, see Section 10.4.4.1, “Geo-replication Checkpoints”.
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL config checkpoint now
    For example,
    # gluster volume geo-replication Volume1 example.com::slave-vol config checkpoint now
  4. Use the following command to verify the checkpoint completion for the geo-replication session
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL status detail
  5. Stop geo-replication between the master and slave, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL stop
    For example:
    # gluster volume geo-replication Volume1 example.com::slave-vol stop
  6. Commit the detach tier operation using the following command:
    # gluster volume tier VOLNAME detach commit
    For example,
    # gluster volume tier test-volume detach commit
    Removing tier can result in data loss. Do you want to Continue? (y/n)
    y
    volume detach-tier commit: success
    Check the detached bricks to ensure all files are migrated.
    If files with data are found on the brick path, copy them via a gluster mount point before re-purposing the removed brick.
    After the detach tier commit is completed, you can verify that the volume is no longer a tier volume by running gluster volume info command.
  7. Restart the geo-replication sessions, using the following command:
    # gluster volume geo-replication MASTER_VOL SLAVE_HOST::SLAVE_VOL start
    For example,
    # gluster volume geo-replication Volume1 example.com::slave-vol start

Part V. Monitor and Tune

Chapter 17. Monitoring Red Hat Gluster Storage Gluster Workload

Monitoring storage volumes is helpful when conducting a capacity planning or performance tuning activity on a Red Hat Gluster Storage volume. You can monitor the Red Hat Gluster Storage volumes with different parameters and use those system outputs to identify and troubleshoot issues.
You can use the volume top and volume profile commands to view vital performance information and identify bottlenecks on each brick of a volume.
You can also perform a statedump of the brick processes and NFS server process of a volume, and also view volume status and volume information.

Note

If you restart the server process, the existing profile and top information will be reset.

17.1. Profiling volumes

17.1.1. Server-side volume profiling using volume profile

The volume profile command provides an interface to get the per-brick or NFS server I/O information for each file operation of a volume. This information helps in identifying the bottlenecks in the storage system.
This section describes how to use the volume profile command.

17.1.1.1. Start Profiling

To view the file operation information of each brick, start the profiling command:
# gluster volume profile VOLNAME start
For example, to start profiling on test-volume:
# gluster volume profile test-volume start
Starting volume profile on test has been successful

Important

Running profile command can affect system performance while the profile information is being collected. Red Hat recommends that profiling should only be used for debugging.
When profiling is started on the volume, the following additional options are displayed when using the volume info command:
diagnostics.count-fop-hits: on
diagnostics.latency-measurement: on

17.1.1.2. Displaying the I/O Information

To view the I/O information of the bricks on a volume, use the following command:
# gluster volume profile VOLNAME info
For example, to view the I/O information of test-volume:
# gluster v profile glustervol info
Brick: rhsqaci-vm33.lab.eng.blr.redhat.com:/bricks/brick0/1
-----------------------------------------------------------
Cumulative Stats:
 %-latency   Avg-latency   Min-Latency   Max-Latency   No. of calls         Fop
 ---------   -----------   -----------   -----------   ------------        ----
      0.00       0.00 us       0.00 us       0.00 us             11     RELEASE
      0.00       0.00 us       0.00 us       0.00 us            238  RELEASEDIR
      0.35     380.05 us     380.05 us     380.05 us              1    SETXATTR
      0.40     107.73 us       5.50 us     413.31 us              4     OPENDIR
      0.62     167.65 us      91.33 us     339.28 us              4      STATFS
      0.86     187.42 us      28.50 us     534.96 us              5    GETXATTR
      2.16     106.54 us      32.16 us     383.58 us             22     ENTRYLK
      2.17     106.97 us      39.01 us     251.65 us             22       FLUSH
      2.92     263.57 us     189.06 us     495.05 us             12     SETATTR
      3.22     124.60 us      43.08 us     311.69 us             28     INODELK
      3.41     616.76 us     319.27 us    1028.72 us              6     READDIR
     10.11     997.03 us     413.73 us    3507.02 us             11      CREATE
     73.79     256.58 us      50.02 us     924.61 us            312      LOOKUP

    Duration: 46537 seconds
   Data Read: 0 bytes
Data Written: 0 bytes

Interval 1 Stats:
 %-latency   Avg-latency   Min-Latency   Max-Latency   No. of calls         Fop
 ---------   -----------   -----------   -----------   ------------        ----
      0.00       0.00 us       0.00 us       0.00 us             11     RELEASE
      0.00       0.00 us       0.00 us       0.00 us              4  RELEASEDIR
      0.35     380.05 us     380.05 us     380.05 us              1    SETXATTR
      0.40     107.73 us       5.50 us     413.31 us              4     OPENDIR
      0.62     167.65 us      91.33 us     339.28 us              4      STATFS
      0.86     187.42 us      28.50 us     534.96 us              5    GETXATTR
      2.16     106.54 us      32.16 us     383.58 us             22     ENTRYLK
      2.17     106.97 us      39.01 us     251.65 us             22       FLUSH
      2.92     263.57 us     189.06 us     495.05 us             12     SETATTR
      3.22     124.60 us      43.08 us     311.69 us             28     INODELK
      3.41     616.76 us     319.27 us    1028.72 us              6     READDIR
     10.11     997.03 us     413.73 us    3507.02 us             11      CREATE
     73.79     256.58 us      50.02 us     924.61 us            312      LOOKUP

    Duration: 347 seconds
   Data Read: 0 bytes
Data Written: 0 bytes

Brick: rhsqaci-vm33.lab.eng.blr.redhat.com:/bricks/brick1/1
-----------------------------------------------------------
Cumulative Stats:
 %-latency   Avg-latency   Min-Latency   Max-Latency   No. of calls         Fop
 ---------   -----------   -----------   -----------   ------------        ----
      0.00       0.00 us       0.00 us       0.00 us             12     RELEASE
      0.00       0.00 us       0.00 us       0.00 us            238  RELEASEDIR
      0.14     146.24 us     146.24 us     146.24 us              1        OPEN
      0.26     266.64 us     266.64 us     266.64 us              1    SETXATTR
      0.26      67.88 us       2.50 us     243.52 us              4     OPENDIR
      0.42     108.83 us      81.87 us     139.11 us              4      STATFS
      0.98     201.26 us      82.36 us     306.38 us              5    GETXATTR
      2.49     116.34 us      23.53 us     304.10 us             22     ENTRYLK
      2.75     236.13 us     124.73 us     358.80 us             12     SETATTR
      3.12     114.82 us      44.34 us     550.01 us             28     INODELK
      3.17     142.00 us      23.16 us     388.56 us             23       FLUSH
      4.37     748.73 us     324.70 us    1115.96 us              6     READDIR
      6.57     614.44 us     364.94 us     807.17 us             11      CREATE
     75.46     248.88 us      66.43 us     599.31 us            312      LOOKUP

    Duration: 46537 seconds
   Data Read: 0 bytes
Data Written: 0 bytes
To view the I/O information of the NFS server on a specified volume, use the following command:
# gluster volume profile VOLNAME info nfs
For example, to view the I/O information of the NFS server on test-volume:
# gluster volume profile test-volume info nfs
NFS Server : localhost
----------------------
Cumulative Stats:
Block Size:              32768b+               65536b+
No. of Reads:                    0                     0
No. of Writes:                 1000                  1000
%-latency   Avg-latency   Min-Latency   Max-Latency   No. of calls         Fop
---------   -----------   -----------   -----------   ------------        ----
0.01     410.33 us     194.00 us     641.00 us              3      STATFS
0.60     465.44 us     346.00 us     867.00 us            147       FSTAT
1.63     187.21 us      67.00 us    6081.00 us           1000     SETATTR
1.94     221.40 us      58.00 us   55399.00 us           1002      ACCESS
2.55     301.39 us      52.00 us   75922.00 us            968        STAT
2.85     326.18 us      88.00 us   66184.00 us           1000    TRUNCATE
4.47     511.89 us      60.00 us  101282.00 us           1000       FLUSH
5.02    3907.40 us    1723.00 us   19508.00 us            147    READDIRP
25.42    2876.37 us     101.00 us  843209.00 us           1012      LOOKUP
55.52    3179.16 us     124.00 us  121158.00 us           2000       WRITE

Duration: 7074 seconds
Data Read: 0 bytes
Data Written: 102400000 bytes

Interval 1 Stats:
Block Size:              32768b+               65536b+
No. of Reads:                    0                     0
No. of Writes:                 1000                  1000
%-latency   Avg-latency   Min-Latency   Max-Latency   No. of calls         Fop
---------   -----------   -----------   -----------   ------------        ----
0.01     410.33 us     194.00 us     641.00 us              3      STATFS
0.60     465.44 us     346.00 us     867.00 us            147       FSTAT
1.63     187.21 us      67.00 us    6081.00 us           1000     SETATTR
1.94     221.40 us      58.00 us   55399.00 us           1002      ACCESS
2.55     301.39 us      52.00 us   75922.00 us            968        STAT
2.85     326.18 us      88.00 us   66184.00 us           1000    TRUNCATE
4.47     511.89 us      60.00 us  101282.00 us           1000       FLUSH
5.02    3907.40 us    1723.00 us   19508.00 us            147    READDIRP
25.41    2878.07 us     101.00 us  843209.00 us           1011      LOOKUP
55.53    3179.16 us     124.00 us  121158.00 us           2000       WRITE

Duration: 330 seconds
Data Read: 0 bytes
Data Written: 102400000 bytes

17.1.1.3. Stop Profiling

To stop profiling on a volume, use the following command:
# gluster volume profile VOLNAME stop
For example, to stop profiling on test-volume:
# gluster volume profile test-volume stop
Stopping volume profile on test has been successful

17.1.2. Client-side volume profiling (FUSE only)

Red Hat Gluster Storage lets you profile how your mount point is being accessed, so that you can investigate latency issues even when you cannot instrument the application accessing your storage.
The io-stats translator records statistics of all file system activity on a Red Hat Gluster Storage volume that travels through a FUSE mount point. It collects information on files opened from the FUSE mount path, the read and write throughput for these files, the number of blocks read and written, and the latency observed for different file operations.
Run the following command to output all recorded statistics for the specified mount point to the specified output file.
# setfattr -n trusted.io-stats-dump -v output_file_id mount_point
This generates a number of files in the /var/run/gluster directory. The output_file_id is not the whole file name, but is used as part of the name of the generated files.

17.2. Running the Volume Top Command

The volume top command allows you to view the glusterFS bricks’ performance metrics, including read, write, file open calls, file read calls, file write calls, directory open calls, and directory real calls. The volume top command displays up to 100 results.
This section describes how to use the volume top command.

17.2.1. Viewing Open File Descriptor Count and Maximum File Descriptor Count

You can view the current open file descriptor count and the list of files that are currently being accessed on the brick with the volume top command. The volume top command also displays the maximum open file descriptor count of files that are currently open, and the maximum number of files opened at any given point of time since the servers are up and running. If the brick name is not specified, then the open file descriptor metrics of all the bricks belonging to the volume displays.
To view the open file descriptor count and the maximum file descriptor count, use the following command:
# gluster volume top VOLNAME open [nfs | brick BRICK-NAME] [list-cnt cnt]
For example, to view the open file descriptor count and the maximum file descriptor count on brick server:/export on test-volume, and list the top 10 open calls:
# gluster volume top test open brick server:/bricks/brick1/test list-cnt 10
Brick: server/bricks/brick1/test
Current open fds: 2, Max open fds: 4, Max openfd time: 2020-10-09 05:57:20.171038
Count	 filename
 =======================
2		/file222
1		/file1

17.2.2. Viewing Highest File Read Calls

You can view a list of files with the highest file read calls on each brick with the volume top command. If the brick name is not specified, a list of 100 files are displayed by default.
To view the highest read() calls, use the following command:
# gluster volume top VOLNAME read [nfs | brick BRICK-NAME] [list-cnt cnt]
For example, to view the highest read calls on brick server:/export of test-volume:
# gluster volume top testvol_distributed-dispersed read brick `hostname`:/bricks/brick1/testvol_distributed-dispersed_brick1/ list-cnt 10
Brick: server/bricks/brick1/testvol_distributed-dispersed_brick1
Count           filename
=======================
9               /user11/dir1/dir4/testfile2.txt
9               /user11/dir1/dir1/testfile0.txt
9               /user11/dir0/dir4/testfile4.txt
9               /user11/dir0/dir3/testfile4.txt
9               /user11/dir0/dir1/testfile0.txt
9               /user11/testfile4.txt
9               /user11/testfile3.txt
5               /user11/dir2/dir1/testfile4.txt
5               /user11/dir2/dir1/testfile0.txt
5               /user11/dir2/testfile2.txt

17.2.3. Viewing Highest File Write Calls

You can view a list of files with the highest file write calls on each brick with the volume top command. If the brick name is not specified, a list of 100 files displays by default.
To view the highest write() calls, use the following command:
# gluster volume top VOLNAME write [nfs | brick BRICK-NAME] [list-cnt cnt]
For example, to view the highest write calls on brick server:/export of test-volume:
# gluster volume top testvol_distributed-dispersed write brick `hostname`:/bricks/brick1/testvol_distributed-dispersed_brick1/ list-cnt 10
Brick: server/bricks/brick1/testvol_distributed-dispersed_brick1
Count           filename
=======================
8               /user12/dir4/dir4/testfile3.txt
8               /user12/dir4/dir3/testfile3.txt
8               /user2/dir4/dir3/testfile4.txt
8               /user3/dir4/dir4/testfile1.txt
8               /user12/dir4/dir2/testfile3.txt
8               /user2/dir4/dir1/testfile0.txt
8               /user11/dir4/dir3/testfile4.txt
8               /user3/dir4/dir2/testfile2.txt
8               /user12/dir4/dir0/testfile0.txt
8               /user11/dir4/dir3/testfile3.txt

17.2.4. Viewing Highest Open Calls on a Directory

You can view a list of files with the highest open calls on the directories of each brick with the volume top command. If the brick name is not specified, the metrics of all bricks belonging to that volume displays.
To view the highest open() calls on each directory, use the following command:
# gluster volume top VOLNAME opendir [brick BRICK-NAME] [list-cnt cnt]
For example, to view the highest open calls on brick server:/export/ of test-volume:
# gluster volume top testvol_distributed-dispersed opendir brick `hostname`:/bricks/brick1/testvol_distributed-dispersed_brick1/ list-cnt 10
Brick: server/bricks/brick1/testvol_distributed-dispersed_brick1
Count           filename
=======================
3               /user2/dir3/dir2
3               /user2/dir3/dir1
3               /user2/dir3/dir0
3               /user2/dir3
3               /user2/dir2/dir4
3               /user2/dir2/dir3
3               /user2/dir2/dir2
3               /user2/dir2/dir1
3               /user2/dir2/dir0
3               /user2/dir2

17.2.5. Viewing Highest Read Calls on a Directory

You can view a list of files with the highest directory read calls on each brick with the volume top command. If the brick name is not specified, the metrics of all bricks belonging to that volume displays.
To view the highest directory read() calls on each brick, use the following command:
# gluster volume top VOLNAME readdir [nfs | brick BRICK-NAME] [list-cnt cnt]
For example, to view the highest directory read calls on brick server:/export/ of test-volume:
# gluster volume top testvol_distributed-dispersed readdir brick `hostname`:/bricks/brick1/testvol_distributed-dispersed_brick1/ list-cnt 10
Brick: server/bricks/brick1/testvol_distributed-dispersed_brick1
Count           filename
=======================
4               /user6/dir2/dir3
4               /user6/dir1/dir4
4               /user6/dir1/dir2
4               /user6/dir1
4               /user6/dir0
4               /user13/dir1/dir1
4               /user3/dir4/dir4
4               /user3/dir3/dir4
4               /user3/dir3/dir3
4               /user3/dir3/dir1

17.2.6. Viewing Read Performance

You can view the read throughput of files on each brick with the volume top command. If the brick name is not specified, the metrics of all the bricks belonging to that volume is displayed. The output is the read throughput.
This command initiates a read() call for the specified count and block size and measures the corresponding throughput directly on the back-end export, bypassing glusterFS processes.
To view the read performance on each brick, use the command, specifying options as needed:
# gluster volume top VOLNAME read-perf [bs blk-size count count] [nfs | brick BRICK-NAME] [list-cnt cnt]
For example, to view the read performance on brick server:/export/ of test-volume, specifying a 256 block size, and list the top 10 results:
# gluster volume top testvol_distributed-dispersed read-perf bs 256 count 1 brick `hostname`:/bricks/brick1/testvol_distributed-dispersed_brick1/ list-cnt 10
Brick: server/bricks/brick1/testvol_distributed-dispersed_brick1
Throughput 10.67 MBps time 0.0000 secs
MBps Filename                                        Time
==== ========                                        ====
   0 /user2/dir3/dir2/testfile3.txt                  2021-02-01 15:47:35.391234
   0 /user2/dir3/dir2/testfile0.txt                  2021-02-01 15:47:35.371018
   0 /user2/dir3/dir1/testfile4.txt                  2021-02-01 15:47:33.375333
   0 /user2/dir3/dir1/testfile0.txt                  2021-02-01 15:47:31.859194
   0 /user2/dir3/dir0/testfile2.txt                  2021-02-01 15:47:31.749105
   0 /user2/dir3/dir0/testfile1.txt                  2021-02-01 15:47:31.728151
   0 /user2/dir3/testfile4.txt                       2021-02-01 15:47:31.296924
   0 /user2/dir3/testfile3.txt                       2021-02-01 15:47:30.988683
   0 /user2/dir3/testfile0.txt                       2021-02-01 15:47:30.557743
   0 /user2/dir2/dir4/testfile4.txt                  2021-02-01 15:47:30.464017

17.2.7. Viewing Write Performance

You can view the write throughput of files on each brick or NFS server with the volume top command. If brick name is not specified, then the metrics of all the bricks belonging to that volume will be displayed. The output will be the write throughput.
This command initiates a write operation for the specified count and block size and measures the corresponding throughput directly on back-end export, bypassing glusterFS processes.
To view the write performance on each brick, use the following command, specifying options as needed:
# gluster volume top VOLNAME write-perf [bs blk-size count count] [nfs | brick BRICK-NAME] [list-cnt cnt]
For example, to view the write performance on brick server:/export/ of test-volume, specifying a 256 block size, and list the top 10 results:
# gluster volume top testvol_distributed-dispersed write-perf bs 256 count 1 brick `hostname`:/bricks/brick1/testvol_distributed-dispersed_brick1/ list-cnt 10
Brick: server/bricks/brick1/testvol_distributed-dispersed_brick1
Throughput 3.88 MBps time 0.0001 secs
MBps Filename                                        Time
==== ========                                        ====
   0 /user12/dir4/dir4/testfile4.txt                 2021-02-01 13:30:32.225628
   0 /user12/dir4/dir4/testfile3.txt                 2021-02-01 13:30:31.771095
   0 /user12/dir4/dir4/testfile0.txt                 2021-02-01 13:30:29.655447
   0 /user12/dir4/dir3/testfile4.txt                 2021-02-01 13:30:29.62920
   0 /user12/dir4/dir3/testfile3.txt                 2021-02-01 13:30:28.995407
   0 /user2/dir4/dir4/testfile2.txt                  2021-02-01 13:30:28.489318
   0 /user2/dir4/dir4/testfile1.txt                  2021-02-01 13:30:27.956523
   0 /user2/dir4/dir3/testfile4.txt                  2021-02-01 13:30:27.34337
   0 /user12/dir4/dir3/testfile0.txt                 2021-02-01 13:30:26.699984
   0 /user3/dir4/dir4/testfile2.txt                  2021-02-01 13:30:26.602165

17.3. Listing Volumes

You can list all volumes in the trusted storage pool using the following command:
# gluster volume list
For example, to list all volumes in the trusted storage pool:
# gluster volume list
test-volume
volume1
volume2
volume3

17.4. Displaying Volume Information

You can display information about a specific volume, or all volumes, as needed, using the following command:
# gluster volume info VOLNAME
For example, to display information about test-volume:
# gluster volume info test-volume
Volume Name: test-volume
Type: Distribute
Status: Created
Number of Bricks: 4
Bricks:
Brick1: server1:/rhgs/brick1
Brick2: server2:/rhgs/brick2
Brick3: server3:/rhgs/brick3
Brick4: server4:/rhgs/brick4

17.5. Obtaining Node Information

A Red Hat Gluster Storage trusted storage pool consists of nodes, volumes, and bricks. The get-state command outputs information about a node to a specified file.
Using the command line interface, external applications can invoke the command on all nodes of the trusted storage pool, and parse and collate the data obtained from all these nodes to get an easy-to-use and complete picture of the state of the trusted storage pool in a machine parseable format.
Executing the get-state Command

The get-state command outputs information about a node to a specified file and can be invoked in different ways. The table below shows the options that can be used with the get-state command.

#  gluster get-state [odir path_to_output_dir] [file filename] [detail|volumeoptions]
Usage:  get-state [options]

Table 17.1. get-state Command Options

Command Description
gluster get-stateglusterd state information is saved in the /var/run/gluster/glusterd_state_timestamp file.
gluster get-state file filenameglusterd state information is saved in the /var/run/gluster/ directory with the filename as specified in the command.
gluster get-state odir directory file filenameglusterd state information is saved in the directory and in the file name as specified in the command.
gluster get-state detailglusterd state information is saved in the /var/run/gluster/glusterd_state_timestamp file, and all clients connected per brick are included in the output.
gluster get-state volumeoptionsglusterd state information is saved in the /var/run/gluster/glusterd_state_timestamp file, and all values for all the volume options are included in the output.
Interpreting the Output with Examples

Invocation of the get-state command saves the information that reflects the node level status of the trusted storage pool as maintained in glusterd (no other daemons are supported as of now) to a file specified in the command. By default, the output will be dumped to /var/run/gluster/glusterd_state_timestamp file .

Invocation of the get-state command provides the following information:

Table 17.2. Output Description

Section Description
Global Displays the UUID and the op-version of the glusterd.
Global options Displays cluster specific options that have been set explicitly through the volume set command.
PeersDisplays the peer node information including its hostname and connection status.
VolumesDisplays the list of volumes created on this node along with the detailed information on each volume.
ServicesDisplays the list of the services configured on this node along with its status.
MiscDisplays miscellaneous information about the node. For example, configured ports.
Example Output for gluster get-state:
# gluster get-state
glusterd state dumped to /var/run/gluster/glusterd_state_timestamp
View the file using the cat state_dump_file_path command:
[Global]
MYUUID: 5392df4c-aeb9-4e8c-9001-58e984897bf6
op-version: 70200

[Global options]

[Peers]
Peer1.primary_hostname: output omitted
Peer1.uuid: 19700669-dff6-4d9f-bf73-ca370c7dc462
Peer1.state: Peer in Cluster
Peer1.connected: Connected
Peer1.othernames:
Peer2.primary_hostname: output omitted
Peer2.uuid: 179d4a5d-0539-4c4e-91a4-2e5bebad25a9
Peer2.state: Peer in Cluster
Peer2.connected: Connected
Peer2.othernames:
Peer3.primary_hostname: output omitted
Peer3.uuid: 80c715a0-5b67-4e7d-8e6e-0449955d1f66
Peer3.state: Peer in Cluster
Peer3.connected: Connected
Peer3.othernames:
Peer4.primary_hostname: output omitted
Peer4.uuid: bed027c6-596f-43a1-b250-11e252a1c524
Peer4.state: Peer in Cluster
Peer4.connected: Connected
Peer4.othernames:
Peer5.primary_hostname: output omitted
Peer5.uuid: d7084399-d47c-4f36-991b-9bd2e9e52dd4
Peer5.state: Peer in Cluster
Peer5.connected: Connected
Peer5.othernames:

[Volumes]
Volume1.name: ecv6012
Volume1.id: e33fbc3e-9240-4024-975d-5f3ed8ce2540
Volume1.type: Distributed-Disperse
Volume1.transport_type: tcp
Volume1.status: Started
Volume1.profile_enabled: 0
Volume1.brickcount: 18
Volume1.Brick1.path: output omitted:/gluster/brick1/ecv6012
Volume1.Brick1.hostname: output omitted
Volume1.Brick2.path: output omitted:/gluster/brick1/ecv6012
Volume1.Brick2.hostname: output omitted
Volume1.Brick3.path: output omitted:/gluster/brick1/ecv6012
Volume1.Brick3.hostname: output omitted
Volume1.Brick3.port: 49152
Volume1.Brick3.rdma_port: 0
Volume1.Brick3.port_registered: 1
Volume1.Brick3.status: Started
Volume1.Brick3.spacefree: 423360098304Bytes
Volume1.Brick3.spacetotal: 427132190720Bytes
Volume1.Brick4.path: output omitted:/gluster/brick1/ecv6012
Volume1.Brick4.hostname: output omitted
Volume1.Brick5.path: output omitted:/gluster/brick1/ecv6012
Volume1.Brick5.hostname: output omitted
Volume1.Brick6.path: output omitted:/gluster/brick1/ecv6012
Volume1.Brick6.hostname: output omitted
Volume1.Brick7.path: output omitted:/gluster/brick2/ecv6012
Volume1.Brick7.hostname: output omitted
Volume1.Brick8.path: output omitted:/gluster/brick2/ecv6012
Volume1.Brick8.hostname: output omitted
Volume1.Brick9.path: output omitted:/gluster/brick2/ecv6012
Volume1.Brick9.hostname: output omitted
Volume1.Brick9.port: 49153
Volume1.Brick9.rdma_port: 0
Volume1.Brick9.port_registered: 1
Volume1.Brick9.status: Started
Volume1.Brick9.spacefree: 423832850432Bytes
Volume1.Brick9.spacetotal: 427132190720Bytes
Volume1.Brick10.path: output omitted:/gluster/brick2/ecv6012
Volume1.Brick10.hostname: output omitted
Volume1.Brick11.path: output omitted:/gluster/brick2/ecv6012
Volume1.Brick11.hostname: output omitted
Volume1.Brick12.path: output omitted:/gluster/brick2/ecv6012
Volume1.Brick12.hostname: output omitted
Volume1.Brick13.path: output omitted:/gluster/brick3/ecv6012
Volume1.Brick13.hostname: output omitted
Volume1.Brick14.path: output omitted:/gluster/brick3/ecv6012
Volume1.Brick14.hostname: output omitted
Volume1.Brick15.path: output omitted:/gluster/brick3/ecv6012
Volume1.Brick15.hostname: output omitted
Volume1.Brick15.port: 49154
Volume1.Brick15.rdma_port: 0
Volume1.Brick15.port_registered: 1
Volume1.Brick15.status: Started
Volume1.Brick15.spacefree: 423877419008Bytes
Volume1.Brick15.spacetotal: 427132190720Bytes
Volume1.Brick16.path: output omitted:/gluster/brick3/ecv6012
Volume1.Brick16.hostname: output omitted
Volume1.Brick17.path: output omitted:/gluster/brick3/ecv6012
Volume1.Brick17.hostname: output omitted
Volume1.Brick18.path: output omitted:/gluster/brick3/ecv6012
Volume1.Brick18.hostname: output omitted
Volume1.snap_count: 0
Volume1.stripe_count: 1
Volume1.replica_count: 1
Volume1.subvol_count: 3
Volume1.arbiter_count: 0
Volume1.disperse_count: 6
Volume1.redundancy_count: 2
Volume1.quorum_status: not_applicable
Volume1.snapd_svc.online_status: Offline
Volume1.snapd_svc.inited: true
Volume1.rebalance.id: 00000000-0000-0000-0000-000000000000
Volume1.rebalance.status: not_started
Volume1.rebalance.failures: 0
Volume1.rebalance.skipped: 0
Volume1.rebalance.lookedup: 0
Volume1.rebalance.files: 0
Volume1.rebalance.data: 0Bytes
Volume1.time_left: 0
Volume1.gsync_count: 0
Volume1.options.server.event-threads: 8
Volume1.options.client.event-threads: 8
Volume1.options.disperse.shd-max-threads: 24
Volume1.options.transport.address-family: inet
Volume1.options.storage.fips-mode-rchecksum: on
Volume1.options.nfs.disable: on


[Services]
svc1.name: glustershd
svc1.online_status: Online

svc2.name: nfs
svc2.online_status: Offline

svc3.name: bitd
svc3.online_status: Offline

svc4.name: scrub
svc4.online_status: Offline

svc5.name: quotad
svc5.online_status: Offline


[Misc]
Base port: 49152
Last allocated port: 49154
Invocation of the gluster get-state volumeoptions lists all volume options irrespective of whether the volume option has been explicitly set or not.
Example Output for gluster get-state volumeoptions:
# gluster get-state volumeoptions
glusterd state dumped to /var/run/gluster/glusterd_state_timestamp
View the file using the cat state_dump_file_path command:
    [Volume Options]
    Volume1.name: ecv6012
    Volume1.options.count: 374
    Volume1.options.value374: (null)
    Volume1.options.key374: features.cloudsync-product-id
    Volume1.options.value373: (null)
    Volume1.options.key373: features.cloudsync-store-id
    Volume1.options.value372: off
    Volume1.options.key372: features.cloudsync-remote-read
    Volume1.options.value371: off
    Volume1.options.key371: features.enforce-mandatory-lock
    Volume1.options.value370: (null)
    Volume1.options.key370: features.cloudsync-storetype
    Volume1.options.value369: on
    Volume1.options.key369: ctime.noatime
    Volume1.options.value368: off
    Volume1.options.key368: features.ctime
    Volume1.options.value367: off
    Volume1.options.key367: features.cloudsync
    Volume1.options.value366: off
    Volume1.options.key366: features.sdfs
    Volume1.options.value365: on
    Volume1.options.key365: disperse.parallel-writes
    Volume1.options.value364:
    Volume1.options.key364: delay-gen.enable
    Volume1.options.value363: 100000
    Volume1.options.key363: delay-gen.delay-duration
    Volume1.options.value362: 10%
    Volume1.options.key362: delay-gen.delay-percentage
    Volume1.options.value361: off
    Volume1.options.key361: debug.delay-gen
    Volume1.options.value360: INFO
    Volume1.options.key360: cluster.daemon-log-level
    Volume1.options.value359: off
    Volume1.options.key359: features.selinux
    Volume1.options.value358: 2
    Volume1.options.key358: cluster.halo-min-replicas
    Volume1.options.value357: 99999
    Volume1.options.key357: cluster.halo-max-replicas
    Volume1.options.value356: 5
    Volume1.options.key356: cluster.halo-max-latency
    Volume1.options.value355: 5
    Volume1.options.key355: cluster.halo-nfsd-max-latency
    Volume1.options.value354: 99999
    Volume1.options.key354: cluster.halo-shd-max-latency
    Volume1.options.value353: False
    Volume1.options.key353: cluster.halo-enabled
    Volume1.options.value352: 4
    Volume1.options.key352: disperse.stripe-cache
    Volume1.options.value351: on
    Volume1.options.key351: disperse.optimistic-change-log
    Volume1.options.value350: 250
    Volume1.options.key350: cluster.max-bricks-per-process
    Volume1.options.value349: 100
    Volume1.options.key349: glusterd.vol_count_per_thread
    Volume1.options.value348: disable
    Volume1.options.key348: cluster.brick-multiplex
    Volume1.options.value347: 60
    Volume1.options.key347: performance.nl-cache-timeout
    Volume1.options.value346: 10MB
    Volume1.options.key346: performance.nl-cache-limit
    Volume1.options.value345: false
    Volume1.options.key345: performance.nl-cache-positive-entry
    Volume1.options.value344: 10MB
    Volume1.options.key344: performance.rda-cache-limit
    Volume1.options.value343: 128KB
    Volume1.options.key343: performance.rda-high-wmark
    Volume1.options.value342: 4096
    Volume1.options.key342: performance.rda-low-wmark
    Volume1.options.value341: 131072
    Volume1.options.key341: performance.rda-request-size
    Volume1.options.value340: off
    Volume1.options.key340: performance.parallel-readdir
    Volume1.options.value339: off
    Volume1.options.key339: cluster.use-compound-fops
    Volume1.options.value338: 1
    Volume1.options.key338: disperse.self-heal-window-size
    Volume1.options.value337: auto
    Volume1.options.key337: disperse.cpu-extensions
    Volume1.options.value336: 1024
    Volume1.options.key336: disperse.shd-wait-qlength
    Volume1.options.value335: 1
    Volume1.options.key335: disperse.shd-max-threads
    Volume1.options.value334: 5
    Volume1.options.key334: features.locks-notify-contention-delay
    Volume1.options.value333: yes
    Volume1.options.key333: features.locks-notify-contention
    Volume1.options.value332: false
    Volume1.options.key332: features.locks-monkey-unlocking
    Volume1.options.value331: 0
    Volume1.options.key331: features.locks-revocation-max-blocked
    Volume1.options.value330: false
    Volume1.options.key330: features.locks-revocation-clear-all
    Volume1.options.value329: 0
    Volume1.options.key329: features.locks-revocation-secs
    Volume1.options.value328: on
    Volume1.options.key328: cluster.granular-entry-heal
    Volume1.options.value327: full
    Volume1.options.key327: cluster.locking-scheme
    Volume1.options.value326: 1024
    Volume1.options.key326: cluster.shd-wait-qlength
    Volume1.options.value325: 1
    Volume1.options.key325: cluster.shd-max-threads
    Volume1.options.value324: gfid-hash
    Volume1.options.key324: disperse.read-policy
    Volume1.options.value323: on
    Volume1.options.key323: dht.force-readdirp
    Volume1.options.value322: 600
    Volume1.options.key322: cluster.heal-timeout
    Volume1.options.value321: 128
    Volume1.options.key321: disperse.heal-wait-qlength
    Volume1.options.value320: 8
    Volume1.options.key320: disperse.background-heals
    Volume1.options.value319: 60
    Volume1.options.key319: features.lease-lock-recall-timeout
    Volume1.options.value318: off
    Volume1.options.key318: features.leases
    Volume1.options.value317: off
    Volume1.options.key317: ganesha.enable
    Volume1.options.value316: 60
    Volume1.options.key316: features.cache-invalidation-timeout
    Volume1.options.value315: off
    Volume1.options.key315: features.cache-invalidation
    Volume1.options.value314: 120
    Volume1.options.key314: features.expiry-time
    Volume1.options.value313: false
    Volume1.options.key313: features.scrub
    Volume1.options.value312: biweekly
    Volume1.options.key312: features.scrub-freq
    Volume1.options.value311: lazy
    Volume1.options.key311: features.scrub-throttle
    Volume1.options.value310: 100
    Volume1.options.key310: features.shard-deletion-rate
    Volume1.options.value309: 16384
    Volume1.options.key309: features.shard-lru-limit
    Volume1.options.value308: 64MB
    Volume1.options.key308: features.shard-block-size
    Volume1.options.value307: off
    Volume1.options.key307: features.shard
    Volume1.options.value306: (null)
    Volume1.options.key306: client.bind-insecure
    Volume1.options.value305: no
    Volume1.options.key305: cluster.quorum-reads
    Volume1.options.value304: enable
    Volume1.options.key304: cluster.disperse-self-heal-daemon
    Volume1.options.value303: off
    Volume1.options.key303: locks.mandatory-locking
    Volume1.options.value302: off
    Volume1.options.key302: locks.trace
    Volume1.options.value301: 25000
    Volume1.options.key301: features.ctr-sql-db-wal-autocheckpoint
    Volume1.options.value300: 12500
    Volume1.options.key300: features.ctr-sql-db-cachesize
    Volume1.options.value299: 300
    Volume1.options.key299: features.ctr_lookupheal_inode_timeout
    Volume1.options.value298: 300
    Volume1.options.key298: features.ctr_lookupheal_link_timeout
    Volume1.options.value297: off
    Volume1.options.key297: features.ctr_link_consistency
    Volume1.options.value296: off
    Volume1.options.key296: features.ctr-record-metadata-heat
    Volume1.options.value295: off
    Volume1.options.key295: features.record-counters
    Volume1.options.value294: off
    Volume1.options.key294: features.ctr-enabled
    Volume1.options.value293: 604800
    Volume1.options.key293: cluster.tier-cold-compact-frequency
    Volume1.options.value292: 604800
    Volume1.options.key292: cluster.tier-hot-compact-frequency
    Volume1.options.value291: on
    Volume1.options.key291: cluster.tier-compact
    Volume1.options.value290: 100
    Volume1.options.key290: cluster.tier-query-limit
    Volume1.options.value289: 10000
    Volume1.options.key289: cluster.tier-max-files
    Volume1.options.value288: 4000
    Volume1.options.key288: cluster.tier-max-mb
    Volume1.options.value287: 0
    Volume1.options.key287: cluster.tier-max-promote-file-size
    Volume1.options.value286: cache
    Volume1.options.key286: cluster.tier-mode
    Volume1.options.value285: 75
    Volume1.options.key285: cluster.watermark-low
    Volume1.options.value284: 90
    Volume1.options.key284: cluster.watermark-hi
    Volume1.options.value283: 3600
    Volume1.options.key283: cluster.tier-demote-frequency
    Volume1.options.value282: 120
    Volume1.options.key282: cluster.tier-promote-frequency
    Volume1.options.value281: off
    Volume1.options.key281: cluster.tier-pause
    Volume1.options.value280: 0
    Volume1.options.key280: cluster.read-freq-threshold
    Volume1.options.value279: 0
    Volume1.options.key279: cluster.write-freq-threshold
    Volume1.options.value278: disable
    Volume1.options.key278: cluster.enable-shared-storage
    Volume1.options.value277: off
    Volume1.options.key277: features.trash-internal-op
    Volume1.options.value276: 5MB
    Volume1.options.key276: features.trash-max-filesize
    Volume1.options.value275: (null)
    Volume1.options.key275: features.trash-eliminate-path
    Volume1.options.value274: .trashcan
    Volume1.options.key274: features.trash-dir
    Volume1.options.value273: off
    Volume1.options.key273: features.trash
    Volume1.options.value272: 120
    Volume1.options.key272: features.barrier-timeout
    Volume1.options.value271: disable
    Volume1.options.key271: features.barrier
    Volume1.options.value270: off
    Volume1.options.key270: changelog.capture-del-path
    Volume1.options.value269: 120
    Volume1.options.key269: changelog.changelog-barrier-timeout
    Volume1.options.value268: 5
    Volume1.options.key268: changelog.fsync-interval
    Volume1.options.value267: 15
    Volume1.options.key267: changelog.rollover-time
    Volume1.options.value266: ascii
    Volume1.options.key266: changelog.encoding
    Volume1.options.value265: {{ brick.path }}/.glusterfs/changelogs
    Volume1.options.key265: changelog.changelog-dir
    Volume1.options.value264: off
    Volume1.options.key264: changelog.changelog
    Volume1.options.value263: 51
    Volume1.options.key263: cluster.server-quorum-ratio
    Volume1.options.value262: off
    Volume1.options.key262: cluster.server-quorum-type
    Volume1.options.value261: off
    Volume1.options.key261: config.gfproxyd
    Volume1.options.value260: off
    Volume1.options.key260: features.ctime
    Volume1.options.value259: 100
    Volume1.options.key259: storage.max-hardlinks
    Volume1.options.value258: 0777
    Volume1.options.key258: storage.create-directory-mask
    Volume1.options.value257: 0777
    Volume1.options.key257: storage.create-mask
    Volume1.options.value256: 0000
    Volume1.options.key256: storage.force-directory-mode
    Volume1.options.value255: 0000
    Volume1.options.key255: storage.force-create-mode
    Volume1.options.value254: on
    Volume1.options.key254: storage.fips-mode-rchecksum
    Volume1.options.value253: 20
    Volume1.options.key253: storage.health-check-timeout
    Volume1.options.value252: 1
    Volume1.options.key252: storage.reserve
    Volume1.options.value251: :
    Volume1.options.key251: storage.gfid2path-separator
    Volume1.options.value250: on
    Volume1.options.key250: storage.gfid2path
    Volume1.options.value249: off
    Volume1.options.key249: storage.build-pgfid
    Volume1.options.value248: 30
    Volume1.options.key248: storage.health-check-interval
    Volume1.options.value247: off
    Volume1.options.key247: storage.node-uuid-pathinfo
    Volume1.options.value246: -1
    Volume1.options.key246: storage.owner-gid
    Volume1.options.value245: -1
    Volume1.options.key245: storage.owner-uid
    Volume1.options.value244: 0
    Volume1.options.key244: storage.batch-fsync-delay-usec
    Volume1.options.value243: reverse-fsync
    Volume1.options.key243: storage.batch-fsync-mode
    Volume1.options.value242: off
    Volume1.options.key242: storage.linux-aio
    Volume1.options.value241: 180
    Volume1.options.key241: features.auto-commit-period
    Volume1.options.value240: relax
    Volume1.options.key240: features.retention-mode
    Volume1.options.value239: 120
    Volume1.options.key239: features.default-retention-period
    Volume1.options.value238: on
    Volume1.options.key238: features.worm-files-deletable
    Volume1.options.value237: off
    Volume1.options.key237: features.worm-file-level
    Volume1.options.value236: off
    Volume1.options.key236: features.worm
    Volume1.options.value235: off
    Volume1.options.key235: features.read-only
    Volume1.options.value234: (null)
    Volume1.options.key234: nfs.auth-cache-ttl-sec
    Volume1.options.value233: (null)
    Volume1.options.key233: nfs.auth-refresh-interval-sec
    Volume1.options.value232: (null)
    Volume1.options.key232: nfs.exports-auth-enable
    Volume1.options.value231: 2
    Volume1.options.key231: nfs.event-threads
    Volume1.options.value230: on
    Volume1.options.key230: nfs.rdirplus
    Volume1.options.value229: (1 * 1048576ULL)
    Volume1.options.key229: nfs.readdir-size
    Volume1.options.value228: (1 * 1048576ULL)
    Volume1.options.key228: nfs.write-size
    Volume1.options.value227: (1 * 1048576ULL)
    Volume1.options.key227: nfs.read-size
    Volume1.options.value226: 0x20000
    Volume1.options.key226: nfs.drc-size
    Volume1.options.value225: off
    Volume1.options.key225: nfs.drc
    Volume1.options.value224: off
    Volume1.options.key224: nfs.server-aux-gids
    Volume1.options.value223: /sbin/rpc.statd
    Volume1.options.key223: nfs.rpc-statd
    Volume1.options.value222: /var/lib/glusterd/nfs/rmtab
    Volume1.options.key222: nfs.mount-rmtab
    Volume1.options.value221: off
    Volume1.options.key221: nfs.mount-udp
    Volume1.options.value220: on
    Volume1.options.key220: nfs.acl
    Volume1.options.value219: on
    Volume1.options.key219: nfs.nlm
    Volume1.options.value218: on
    Volume1.options.key218: nfs.disable
    Volume1.options.value217:
    Volume1.options.key217: nfs.export-dir
    Volume1.options.value216: read-write
    Volume1.options.key216: nfs.volume-access
    Volume1.options.value215: off
    Volume1.options.key215: nfs.trusted-write
    Volume1.options.value214: off
    Volume1.options.key214: nfs.trusted-sync
    Volume1.options.value213: off
    Volume1.options.key213: nfs.ports-insecure
    Volume1.options.value212: none
    Volume1.options.key212: nfs.rpc-auth-reject
    Volume1.options.value211: all
    Volume1.options.key211: nfs.rpc-auth-allow
    Volume1.options.value210: on
    Volume1.options.key210: nfs.rpc-auth-null
    Volume1.options.value209: on
    Volume1.options.key209: nfs.rpc-auth-unix
    Volume1.options.value208: 2049
    Volume1.options.key208: nfs.port
    Volume1.options.value207: 16
    Volume1.options.key207: nfs.outstanding-rpc-limit
    Volume1.options.value206: on
    Volume1.options.key206: nfs.register-with-portmap
    Volume1.options.value205: off
    Volume1.options.key205: nfs.dynamic-volumes
    Volume1.options.value204: off
    Volume1.options.key204: nfs.addr-namelookup
    Volume1.options.value203: on
    Volume1.options.key203: nfs.export-volumes
    Volume1.options.value202: on
    Volume1.options.key202: nfs.export-dirs
    Volume1.options.value201: 15
    Volume1.options.key201: nfs.mem-factor
    Volume1.options.value200: no
    Volume1.options.key200: nfs.enable-ino32
    Volume1.options.value199: (null)
    Volume1.options.key199: debug.error-fops
    Volume1.options.value198: off
    Volume1.options.key198: debug.random-failure
    Volume1.options.value197: (null)
    Volume1.options.key197: debug.error-number
    Volume1.options.value196: (null)
    Volume1.options.key196: debug.error-failure
    Volume1.options.value195: off
    Volume1.options.key195: debug.error-gen
    Volume1.options.value194: (null)
    Volume1.options.key194: debug.include-ops
    Volume1.options.value193: (null)
    Volume1.options.key193: debug.exclude-ops
    Volume1.options.value192: no
    Volume1.options.key192: debug.log-file
    Volume1.options.value191: no
    Volume1.options.key191: debug.log-history
    Volume1.options.value190: off
    Volume1.options.key190: debug.trace
    Volume1.options.value189: disable
    Volume1.options.key189: features.bitrot
    Volume1.options.value188: off
    Volume1.options.key188: features.inode-quota
    Volume1.options.value187: off
    Volume1.options.key187: features.quota
    Volume1.options.value186: off
    Volume1.options.key186: geo-replication.ignore-pid-check
    Volume1.options.value185: off
    Volume1.options.key185: geo-replication.ignore-pid-check
    Volume1.options.value184: off
    Volume1.options.key184: geo-replication.indexing
    Volume1.options.value183: off
    Volume1.options.key183: geo-replication.indexing
    Volume1.options.value182: off
    Volume1.options.key182: features.quota-deem-statfs
    Volume1.options.value181: 86400
    Volume1.options.key181: features.alert-time
    Volume1.options.value180: 5
    Volume1.options.key180: features.hard-timeout
    Volume1.options.value179: 60
    Volume1.options.key179: features.soft-timeout
    Volume1.options.value178: 80%
    Volume1.options.key178: features.default-soft-limit
    Volume1.options.value171: off
    Volume1.options.key171: features.tag-namespaces
    Volume1.options.value170: off
    Volume1.options.key170: features.show-snapshot-directory
    Volume1.options.value169: .snaps
    Volume1.options.key169: features.snapshot-directory
    Volume1.options.value168: off
    Volume1.options.key168: features.uss
    Volume1.options.value167: true
    Volume1.options.key167: performance.global-cache-invalidation
    Volume1.options.value166: false
    Volume1.options.key166: performance.cache-invalidation
    Volume1.options.value165: true
    Volume1.options.key165: performance.force-readdirp
    Volume1.options.value164: off
    Volume1.options.key164: performance.nfs.io-threads
    Volume1.options.value163: off
    Volume1.options.key163: performance.nfs.stat-prefetch
    Volume1.options.value162: off
    Volume1.options.key162: performance.nfs.quick-read
    Volume1.options.value161: off
    Volume1.options.key161: performance.nfs.io-cache
    Volume1.options.value160: off
    Volume1.options.key160: performance.nfs.read-ahead
    Volume1.options.value159: on
    Volume1.options.key159: performance.nfs.write-behind
    Volume1.options.value158: off
    Volume1.options.key158: performance.client-io-threads
    Volume1.options.value157: on
    Volume1.options.key157: performance.stat-prefetch
    Volume1.options.value156: off
    Volume1.options.key156: performance.nl-cache
    Volume1.options.value155: on
    Volume1.options.key155: performance.quick-read
    Volume1.options.value154: on
    Volume1.options.key154: performance.open-behind
    Volume1.options.value153: on
    Volume1.options.key153: performance.io-cache
    Volume1.options.value152: off
    Volume1.options.key152: performance.readdir-ahead
    Volume1.options.value151: on
    Volume1.options.key151: performance.read-ahead
    Volume1.options.value150: on
    Volume1.options.key150: performance.write-behind
    Volume1.options.value149: inet
    Volume1.options.key149: transport.address-family
    Volume1.options.value148: 1024
    Volume1.options.key148: transport.listen-backlog
    Volume1.options.value147: 9
    Volume1.options.key147: server.keepalive-count
    Volume1.options.value146: 2
    Volume1.options.key146: server.keepalive-interval
    Volume1.options.value145: 20
    Volume1.options.key145: server.keepalive-time
    Volume1.options.value144: 42
    Volume1.options.key144: server.tcp-user-timeout
    Volume1.options.value143: 2
    Volume1.options.key143: server.event-threads
    Volume1.options.value142: (null)
    Volume1.options.key142: server.own-thread
    Volume1.options.value141: 300
    Volume1.options.key141: server.gid-timeout
    Volume1.options.value140: on
    Volume1.options.key140: client.send-gids
    Volume1.options.value139: on
    Volume1.options.key139: server.dynamic-auth
    Volume1.options.value138: off
    Volume1.options.key138: server.manage-gids
    Volume1.options.value137: *
    Volume1.options.key137: auth.ssl-allow
    Volume1.options.value136: off
    Volume1.options.key136: server.ssl
    Volume1.options.value135: 64
    Volume1.options.key135: server.outstanding-rpc-limit
    Volume1.options.value134: /var/run/gluster
    Volume1.options.key134: server.statedump-path
    Volume1.options.value133: 65534
    Volume1.options.key133: server.anongid
    Volume1.options.value132: 65534
    Volume1.options.key132: server.anonuid
    Volume1.options.value131: off
    Volume1.options.key131: server.all-squash
    Volume1.options.value130: off
    Volume1.options.key130: server.root-squash
    Volume1.options.value129: on
    Volume1.options.key129: server.allow-insecure
    Volume1.options.value128: 1
    Volume1.options.key128: transport.keepalive
    Volume1.options.value127: (null)
    Volume1.options.key127: auth.reject
    Volume1.options.value126: *
    Volume1.options.key126: auth.allow
    Volume1.options.value125: 16384
    Volume1.options.key125: network.inode-lru-limit
    Volume1.options.value124: (null)
    Volume1.options.key124: network.tcp-window-size
    Volume1.options.value123: 9
    Volume1.options.key123: client.keepalive-count
    Volume1.options.value122: 2
    Volume1.options.key122: client.keepalive-interval
    Volume1.options.value121: 20
    Volume1.options.key121: client.keepalive-time
    Volume1.options.value120: 0
    Volume1.options.key120: client.tcp-user-timeout
    Volume1.options.value119: 2
    Volume1.options.key119: client.event-threads
    Volume1.options.value118: disable
    Volume1.options.key118: network.remote-dio
    Volume1.options.value117: off
    Volume1.options.key117: client.ssl
    Volume1.options.value116: (null)
    Volume1.options.key116: network.tcp-window-size
    Volume1.options.value115: 42
    Volume1.options.key115: network.ping-timeout
    Volume1.options.value114: 1800
    Volume1.options.key114: network.frame-timeout
    Volume1.options.value113: off
    Volume1.options.key113: features.encryption
    Volume1.options.value112: false
    Volume1.options.key112: performance.nl-cache-pass-through
    Volume1.options.value111:
    Volume1.options.key111: performance.xattr-cache-list
    Volume1.options.value110: off
    Volume1.options.key110: performance.md-cache-statfs
    Volume1.options.value109: true
    Volume1.options.key109: performance.cache-ima-xattrs
    Volume1.options.value108: true
    Volume1.options.key108: performance.cache-capability-xattrs
    Volume1.options.value107: false
    Volume1.options.key107: performance.cache-samba-metadata
    Volume1.options.value106: true
    Volume1.options.key106: performance.cache-swift-metadata
    Volume1.options.value105: 1
    Volume1.options.key105: performance.md-cache-timeout
    Volume1.options.value104: false
    Volume1.options.key104: performance.md-cache-pass-through
    Volume1.options.value103: false
    Volume1.options.key103: performance.readdir-ahead-pass-through
    Volume1.options.value102: false
    Volume1.options.key102: performance.read-ahead-pass-through
    Volume1.options.value101: 4
    Volume1.options.key101: performance.read-ahead-page-count
    Volume1.options.value100: false
    Volume1.options.key100: performance.open-behind-pass-through
    Volume1.options.value99: yes
    Volume1.options.key99: performance.read-after-open
    Volume1.options.value98: yes
    Volume1.options.key98: performance.lazy-open
    Volume1.options.value97: on
    Volume1.options.key97: performance.nfs.write-behind-trickling-writes
    Volume1.options.value96: 128KB
    Volume1.options.key96: performance.aggregate-size
    Volume1.options.value95: on
    Volume1.options.key95: performance.write-behind-trickling-writes
    Volume1.options.value94: off
    Volume1.options.key94: performance.nfs.strict-write-ordering
    Volume1.options.value93: off
    Volume1.options.key93: performance.strict-write-ordering
    Volume1.options.value92: off
    Volume1.options.key92: performance.nfs.strict-o-direct
    Volume1.options.value91: off
    Volume1.options.key91: performance.strict-o-direct
    Volume1.options.value90: 1MB
    Volume1.options.key90: performance.nfs.write-behind-window-size
    Volume1.options.value89: off
    Volume1.options.key89: performance.resync-failed-syncs-after-fsync
    Volume1.options.value88: 1MB
    Volume1.options.key88: performance.write-behind-window-size
    Volume1.options.value87: on
    Volume1.options.key87: performance.nfs.flush-behind
    Volume1.options.value86: on
    Volume1.options.key86: performance.flush-behind
    Volume1.options.value85: false
    Volume1.options.key85: performance.ctime-invalidation
    Volume1.options.value84: false
    Volume1.options.key84: performance.quick-read-cache-invalidation
    Volume1.options.value83: 1
    Volume1.options.key83: performance.qr-cache-timeout
    Volume1.options.value82: 128MB
    Volume1.options.key82: performance.cache-size
    Volume1.options.value81: false
    Volume1.options.key81: performance.io-cache-pass-through
    Volume1.options.value80: false
    Volume1.options.key80: performance.iot-pass-through
    Volume1.options.value79: off
    Volume1.options.key79: performance.iot-cleanup-disconnected-reqs
    Volume1.options.value78: (null)
    Volume1.options.key78: performance.iot-watchdog-secs
    Volume1.options.value77: on
    Volume1.options.key77: performance.enable-least-priority
    Volume1.options.value76: 1
    Volume1.options.key76: performance.least-prio-threads
    Volume1.options.value75: 16
    Volume1.options.key75: performance.low-prio-threads
    Volume1.options.value74: 16
    Volume1.options.key74: performance.normal-prio-threads
    Volume1.options.value73: 16
    Volume1.options.key73: performance.high-prio-threads
    Volume1.options.value72: 16
    Volume1.options.key72: performance.io-thread-count
    Volume1.options.value71: 32MB
    Volume1.options.key71: performance.cache-size
    Volume1.options.value70:
    Volume1.options.key70: performance.cache-priority
    Volume1.options.value69: 1
    Volume1.options.key69: performance.cache-refresh-timeout
    Volume1.options.value68: 0
    Volume1.options.key68: performance.cache-min-file-size
    Volume1.options.value67: 0
    Volume1.options.key67: performance.cache-max-file-size
    Volume1.options.value66: 86400
    Volume1.options.key66: diagnostics.stats-dnscache-ttl-sec
    Volume1.options.value65: 65535
    Volume1.options.key65: diagnostics.fop-sample-buf-size
    Volume1.options.value64: json
    Volume1.options.key64: diagnostics.stats-dump-format
    Volume1.options.value63: 0
    Volume1.options.key63: diagnostics.fop-sample-interval
    Volume1.options.value62: 0
    Volume1.options.key62: diagnostics.stats-dump-interval
    Volume1.options.value61: 120
    Volume1.options.key61: diagnostics.client-log-flush-timeout
    Volume1.options.value60: 120
    Volume1.options.key60: diagnostics.brick-log-flush-timeout
    Volume1.options.value59: 5
    Volume1.options.key59: diagnostics.client-log-buf-size
    Volume1.options.value58: 5
    Volume1.options.key58: diagnostics.brick-log-buf-size
    Volume1.options.value57: (null)
    Volume1.options.key57: diagnostics.client-log-format
    Volume1.options.value56: (null)
    Volume1.options.key56: diagnostics.brick-log-format
    Volume1.options.value55: (null)
    Volume1.options.key55: diagnostics.client-logger
    Volume1.options.value54: (null)
    Volume1.options.key54: diagnostics.brick-logger
    Volume1.options.value53: CRITICAL
    Volume1.options.key53: diagnostics.client-sys-log-level
    Volume1.options.value52: CRITICAL
    Volume1.options.key52: diagnostics.brick-sys-log-level
    Volume1.options.value51: INFO
    Volume1.options.key51: diagnostics.client-log-level
    Volume1.options.value50: INFO
    Volume1.options.key50: diagnostics.brick-log-level
    Volume1.options.value49: off
    Volume1.options.key49: diagnostics.count-fop-hits
    Volume1.options.value48: off
    Volume1.options.key48: diagnostics.dump-fd-stats
    Volume1.options.value47: off
    Volume1.options.key47: diagnostics.latency-measurement
    Volume1.options.value46: yes
    Volume1.options.key46: cluster.full-lock
    Volume1.options.value45: none
    Volume1.options.key45: cluster.favorite-child-policy
    Volume1.options.value44: 128
    Volume1.options.key44: cluster.heal-wait-queue-length
    Volume1.options.value43: no
    Volume1.options.key43: cluster.consistent-metadata
    Volume1.options.value42: on
    Volume1.options.key42: cluster.ensure-durability
    Volume1.options.value41: 1
    Volume1.options.key41: cluster.post-op-delay-secs
    Volume1.options.value40: 1KB
    Volume1.options.key40: cluster.self-heal-readdir-size
    Volume1.options.value39: true
    Volume1.options.key39: cluster.choose-local
    Volume1.options.value38: (null)
    Volume1.options.key38: cluster.quorum-count
    Volume1.options.value37: auto
    Volume1.options.key37: cluster.quorum-type
    Volume1.options.value36: 1
    Volume1.options.key36: disperse.other-eager-lock-timeout
    Volume1.options.value35: 1
    Volume1.options.key35: disperse.eager-lock-timeout
    Volume1.options.value34: on
    Volume1.options.key34: disperse.other-eager-lock
    Volume1.options.value33: on
    Volume1.options.key33: disperse.eager-lock
    Volume1.options.value32: on
    Volume1.options.key32: cluster.eager-lock
    Volume1.options.value31: (null)
    Volume1.options.key31: cluster.data-self-heal-algorithm
    Volume1.options.value30: on
    Volume1.options.key30: cluster.metadata-change-log
    Volume1.options.value29: on
    Volume1.options.key29: cluster.data-change-log
    Volume1.options.value28: 1
    Volume1.options.key28: cluster.self-heal-window-size
    Volume1.options.value27: 600
    Volume1.options.key27: cluster.heal-timeout
    Volume1.options.value26: on
    Volume1.options.key26: cluster.self-heal-daemon
    Volume1.options.value25: off
    Volume1.options.key25: cluster.entry-self-heal
    Volume1.options.value24: off
    Volume1.options.key24: cluster.data-self-heal
    Volume1.options.value23: off
    Volume1.options.key23: cluster.metadata-self-heal
    Volume1.options.value22: 8
    Volume1.options.key22: cluster.background-self-heal-count
    Volume1.options.value21: 1
    Volume1.options.key21: cluster.read-hash-mode
    Volume1.options.value20: -1
    Volume1.options.key20: cluster.read-subvolume-index
    Volume1.options.value19: (null)
    Volume1.options.key19: cluster.read-subvolume
    Volume1.options.value18: on
    Volume1.options.key18: cluster.entry-change-log
    Volume1.options.value17: (null)
    Volume1.options.key17: cluster.switch-pattern
    Volume1.options.value16: on
    Volume1.options.key16: cluster.weighted-rebalance
    Volume1.options.value15: (null)
    Volume1.options.key15: cluster.local-volume-name
    Volume1.options.value14: off
    Volume1.options.key14: cluster.force-migration
    Volume1.options.value13: off
    Volume1.options.key13: cluster.lock-migration
    Volume1.options.value12: normal
    Volume1.options.key12: cluster.rebal-throttle
    Volume1.options.value11: off
    Volume1.options.key11: cluster.randomize-hash-range-by-gfid
    Volume1.options.value10: trusted.glusterfs.dht
    Volume1.options.key10: cluster.dht-xattr-name
    Volume1.options.value9: (null)
    Volume1.options.key9: cluster.extra-hash-regex
    Volume1.options.value8: (null)
    Volume1.options.key8: cluster.rsync-hash-regex
    Volume1.options.value7: off
    Volume1.options.key7: cluster.readdir-optimize
    Volume1.options.value6: (null)
    Volume1.options.key6: cluster.subvols-per-directory
    Volume1.options.value5: off
    Volume1.options.key5: cluster.rebalance-stats
    Volume1.options.value4: 5%
    Volume1.options.key4: cluster.min-free-inodes
    Volume1.options.value3: 10%
    Volume1.options.key3: cluster.min-free-disk
    Volume1.options.value2: on
    Volume1.options.key2: cluster.lookup-optimize
    Volume1.options.value1: on
    Volume1.options.key1: cluster.lookup-unhashed

17.6. Retrieving Current Volume Option Settings

Red Hat Gluster Storage allows storage administrators to retrieve the value of a specific volume option. You can also retrieve all the values of the volume options and all global options associated to a gluster volume. To retrieve the value of volume options, use the gluster volume get command. If a volume option is reconfigured for a volume, then the same value is displayed. If the volume option is not reconfigured, the default value is displayed.
The syntax is # gluster volume get <VOLNAME|all> <key|all>

17.6.1. Retrieving Value of a Specific Volume Option

To fetch the value of a specific volume option, execute the following command:
# gluster volume get <VOLNAME> <key>
Where,
VOLNAME: The volume name
key: The value of the volume option
For example:
# gluster volume get test-vol nfs.disable
 Option Value
 ------ -----
 nfs.disable on

17.6.2. Retrieving all Options of a Volume

To fetch the values of all the volume options, execute the following command:
# gluster volume get <VOLNAME> all
Where,
VOLNAME: The volume name
For example:
# gluster volume get test-vol all
 Option Value
 ------ -----
 cluster.lookup-unhashed on
 cluster.lookup-optimize on
 cluster.min-free-disk 10%
 cluster.min-free-inodes 5%
 cluster.rebalance-stats off
 cluster.subvols-per-directory (null)
 ....

17.6.3. Retrieving all Global Options

To fetch the values of all global options, execute the following command:
# gluster volume get all all
For example:
# gluster volume get all all

Option                                  Value
------                                  -----
cluster.server-quorum-ratio             51
cluster.enable-shared-storage           disable
cluster.op-version                      70200
cluster.max-op-version                  70200
cluster.brick-multiplex                 disable
cluster.max-bricks-per-process          250
cluster.daemon-log-level                INFO

17.7. Viewing complete volume state with statedump

The statedump subcommand writes out details of the current state of a specified process, including internal variables and other information that is useful for troubleshooting.
The command is used as follows:
# gluster volume statedump VOLNAME [[nfs|quotad] [all|mem|iobuf|callpool|priv|fd|inode|history] | [client hostname:pid]]

17.7.1. Gathering information from the server

You can output all available state information, or limit statedump output to specific details, by using the statedump command with one of the following parameters.
all
Dumps all available state information.
mem
Dumps the memory usage and memory pool details of the bricks.
iobuf
Dumps iobuf details of the bricks.
priv
Dumps private information of loaded translators.
callpool
Dumps the pending calls of the volume.
fd
Dumps the open file descriptor tables of the volume.
inode
Dumps the inode tables of the volume.
history
Dumps the event history of the volume
For example, to write out all available information about the data volume, run the following command on the server:
# gluster volume statedump data all
If you only want to see details about the event history, run the following:
# gluster volume statedump data history
The nfs parameter is required to gather details about volumes shared via NFS. It can be combined with any of the above parameters to filter output.
# gluster volume statedump VOLNAME nfs all
The quotad parameter is required to gather details about the quota daemon. The following command writes out the state of the quota daemon across all nodes.
# gluster volume statedump VOLNAME quotad
If you need to see the state of a different process, such as the self-heal daemon, you can do so by running the following command using the process identifier of that process.
# kill -SIGUSR1 pid

17.7.2. Gathering information from the client

The statedump subcommand writes out details of the current state of a specified process, including internal variables and other information that is useful for troubleshooting.
To generate a statedump for client-side processes, using libgfapi, run the following command on a gluster node that is connected to the libgfapi application.
# gluster volume statedump VOLNAME client hostname:pid

Important

If you are using either NFS Ganesha or Samba service and you need to see the state of its clients, ensure that you use localhost instead of hostname. For example:
# gluster volume statedump VOLNAME client localhost:pid
If you need to get the state of glusterfs fuse mount process, you can do so by running the following command using the process identifier of that process.
# kill -SIGUSR1 pid

Important

If you have a gfapi based application and you need to see the state of its clients, ensure that the user running the gfapi application is a member of the gluster group. For example, if your gfapi application is run by user qemu, ensure that qemu is added to the gluster group by running the following command:
# usermod -a -G gluster qemu

17.7.3. Controlling statedump output location

Information is saved to the /var/run/gluster directory by default. Output files are named according to the following conventions:
  • For brick processes, brick_path.brick_pid.dump
  • For volume processes and kill command results, glusterdump-glusterd_pid.dump.timestamp
To change where the output files of a particular volume are saved, use the server.statedump-path parameter, like so:
# gluster volume set VOLNAME server.statedump-path PATH

17.8. Displaying Volume Status

You can display the status information about a specific volume, brick, or all volumes, as needed. Status information can be used to understand the current status of the brick, NFS processes, self-heal daemon and overall file system. Status information can also be used to monitor and debug the volume information. You can view status of the volume along with the details:
  • detail - Displays additional information about the bricks.
  • clients - Displays the list of clients connected to the volume.
  • mem - Displays the memory usage and memory pool details of the bricks.
  • inode - Displays the inode tables of the volume.
  • fd - Displays the open file descriptor tables of the volume.
  • callpool - Displays the pending calls of the volume.
Setting Timeout Period

When you try to obtain information of a specific volume, the command may get timed out from the CLI if the originator glusterd takes longer than 120 seconds, the default time out, to aggregate the results from all the other glusterds and report back to CLI.

You can use the --timeout option to ensure that the commands do not get timed out by 120 seconds.
For example,
# gluster volume status --timeout=500  VOLNAME  inode
It is recommended to use --timeout option when obtaining information about the inodes or clients or details as they frequently get timed out.
Display information about a specific volume using the following command:
# gluster volume status --timeout=value_in_seconds [all|VOLNAME [nfs | shd | BRICKNAME]] [detail |clients | mem | inode | fd |callpool]
For example, to display information about test-volume:
# gluster volume status test-volume
Status of volume: test-volume
Gluster process                        Port    Online   Pid
------------------------------------------------------------
Brick Server1:/rhgs/brick0/rep1        24010   Y       18474
Brick Server1:/rhgs/brick0/rep2        24011   Y       18479
NFS Server on localhost                38467   Y       18486
Self-heal Daemon on localhost          N/A     Y       18491
The self-heal daemon status will be displayed only for replicated volumes.
Display information about all volumes using the command:
# gluster volume status all
# gluster volume status all
Status of volume: test
Gluster process                       Port    Online   Pid
-----------------------------------------------------------
Brick Server1:/rhgs/brick0/test       24009   Y       29197
NFS Server on localhost               38467   Y       18486

Status of volume: test-volume
Gluster process                       Port    Online   Pid
------------------------------------------------------------
Brick Server1:/rhgs/brick0/rep1       24010   Y       18474
Brick Server1:/rhgs/brick0/rep2       24011   Y       18479
NFS Server on localhost               38467   Y       18486
Self-heal Daemon on localhost         N/A     Y       18491
Display additional information about the bricks using the command:
# gluster volume status VOLNAME detail
For example, to display additional information about the bricks of test-volume:
# gluster volume status test-volume detail
Status of volume: test-vol
------------------------------------------------------------------------------
Brick                : Brick Server1:/rhgs/test
Port                 : 24012
Online               : Y
Pid                  : 18649
File System          : xfs
Device               : /dev/sda1
Mount Options        : rw,relatime,user_xattr,acl,commit=600,barrier=1,data=ordered
Inode Size           : 256
Disk Space Free      : 22.1GB
Total Disk Space     : 46.5GB
Inode Count          : 3055616
Free Inodes          : 2577164
Detailed information is not available for NFS and the self-heal daemon.
Display the list of clients accessing the volumes using the command:
# gluster volume status VOLNAME clients
For example, to display the list of clients connected to test-volume:
# gluster volume status test-volume clients
Brick : Server1:/rhgs/brick0/1
Clients connected : 2
Hostname          Bytes Read   BytesWritten     OpVersion
--------          ---------    ------------     ---------
127.0.0.1:1013    776          676                 70200
127.0.0.1:1012    50440        51200               70200
Client information is not available for the self-heal daemon.
Display the memory usage and memory pool details of the bricks on a volume using the command:
# gluster volume status VOLNAME mem
For example, to display the memory usage and memory pool details for the bricks on test-volume:
# gluster volume status glustervol mem
Memory status for volume : glustervol
----------------------------------------------
Brick : rhsqaci-vm33.lab.eng.blr.redhat.com:/bricks/brick0/1
Mallinfo
--------
Arena    : 11509760
Ordblks  : 278
Smblks   : 16
Hblks    : 17
Hblkhd   : 17350656
Usmblks  : 0
Fsmblks  : 1376
Uordblks : 3850640
Fordblks : 7659120
Keepcost : 121632

----------------------------------------------
Brick : rhsqaci-vm44.lab.eng.blr.redhat.com:/bricks/brick0/1
Mallinfo
--------
Arena    : 11595776
Ordblks  : 329
Smblks   : 44
Hblks    : 17
Hblkhd   : 17350656
Usmblks  : 0
Fsmblks  : 4240
Uordblks : 3888928
Fordblks : 7706848
Keepcost : 121632

----------------------------------------------
Brick : rhsqaci-vm32.lab.eng.blr.redhat.com:/bricks/brick0/1
Mallinfo
--------
Arena    : 9695232
Ordblks  : 306
Smblks   : 67
Hblks    : 17
Hblkhd   : 17350656
Usmblks  : 0
Fsmblks  : 5616
Uordblks : 3890736
Fordblks : 5804496
Keepcost : 121632
Display the inode tables of the volume using the command:
# gluster volume status VOLNAME inode
For example, to display the inode tables of test-volume:
# gluster volume status test inode
inode tables for volume test
----------------------------------------------
Brick : rhsqaci-vm35.lab.eng.blr.redhat.com:/bricks/brick1/test
Connection 1:
LRU limit     : 16384
Active Inodes : 1000
LRU Inodes    : 1
Purge Inodes  : 0
Display the open file descriptor tables of the volume using the command:
# gluster volume status VOLNAME fd
For example, to display the open file descriptor tables of test-volume:
# gluster volume status test-volume fd

FD tables for volume test-volume
----------------------------------------------
Brick : Server1:/rhgs/brick0/1
Connection 1:
RefCount = 0  MaxFDs = 128  FirstFree = 4
FD Entry            PID                 RefCount            Flags
--------            ---                 --------            -----
0                   26311               1                   2
1                   26310               3                   2
2                   26310               1                   2
3                   26311               3                   2

Connection 2:
RefCount = 0  MaxFDs = 128  FirstFree = 0
No open fds

Connection 3:
RefCount = 0  MaxFDs = 128  FirstFree = 0
No open fds
FD information is not available for NFS and the self-heal daemon.
Display the pending calls of the volume using the command:
# gluster volume status VOLNAME callpool
Note, each call has a call stack containing call frames.
For example, to display the pending calls of test-volume:
# gluster volume status test-volume callpool

Pending calls for volume test-volume
----------------------------------------------
Brick : Server1:/rhgs/brick0/1
Pending calls: 2
Call Stack1
 UID    : 0
 GID    : 0
 PID    : 26338
 Unique : 192138
 Frames : 7
 Frame 1
  Ref Count   = 1
  Translator  = test-volume-server
  Completed   = No
 Frame 2
  Ref Count   = 0
  Translator  = test-volume-posix
  Completed   = No
  Parent      = test-volume-access-control
  Wind From   = default_fsync
  Wind To     = FIRST_CHILD(this)->fops->fsync
 Frame 3
  Ref Count   = 1
  Translator  = test-volume-access-control
  Completed   = No
  Parent      = repl-locks
  Wind From   = default_fsync
  Wind To     = FIRST_CHILD(this)->fops->fsync
 Frame 4
  Ref Count   = 1
  Translator  = test-volume-locks
  Completed   = No
  Parent      = test-volume-io-threads
  Wind From   = iot_fsync_wrapper
  Wind To     = FIRST_CHILD (this)->fops->fsync
 Frame 5
  Ref Count   = 1
  Translator  = test-volume-io-threads
  Completed   = No
  Parent      = test-volume-marker
  Wind From   = default_fsync
  Wind To     = FIRST_CHILD(this)->fops->fsync
 Frame 6
  Ref Count   = 1
  Translator  = test-volume-marker
  Completed   = No
  Parent      = /export/1
  Wind From   = io_stats_fsync
  Wind To     = FIRST_CHILD(this)->fops->fsync
 Frame 7
  Ref Count   = 1
  Translator  = /export/1
  Completed   = No
  Parent      = test-volume-server
  Wind From   = server_fsync_resume
  Wind To     = bound_xl->fops->fsync

17.9. Troubleshooting issues in the Red Hat Gluster Storage Trusted Storage Pool

17.9.1. Troubleshooting a network issue in the Red Hat Gluster Storage Trusted Storage Pool

When enabling the network components to communicate with Jumbo frames in a Red Hat Gluster Storage Trusted Storage Pool, ensure that all the network components such as switches, Red Hat Gluster Storage nodes etc are configured properly. Verify the network configuration by running the ping from one Red Hat Gluster Storage node to another.
If the nodes in the Red Hat Gluster Storage Trusted Storage Pool or any other network components are not configured to fully support Jumbo frames, the ping command times out and displays the following error:
# ping -s 1600 '-Mdo'IP_ADDRESS
local error: Message too long, mtu=1500

Chapter 18. Managing Resource Usage

When Red Hat Gluster Storage is deployed on the same machine as other resource intensive software and services, it can be useful to limit the resources that glusterd attempts to use in order to avoid resource contention between processes.
Resource management works differently on Red Hat Enterprise Linux 6. See the Red Hat Enterprise Linux 6 Resource Management Guide for details: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/ch-Using_Control_Groups.html

Important

Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide

Procedure 18.1. Controlling CPU Usage for a Gluster Daemon

The control-cpu-load script provides a utility to control CPU utilization for any Gluster daemon by using the cgroup framework to configure CPU quota for a process.
  1. Navigate to the scripts folder by using the following command:
    # cd /usr/share/glusterfs/scripts
  2. Determine the PID of the required gluster daemon by using the following command:
    # ps -aef | grep daemon_name
    The output will be in the following format:
    root      1565...output omitted...grep --color=auto daemon_name
    In this output, 1565 represents the PID of the daemon service. PIDs are unlikely to be the same on different systems, or for different instances of the daemon, so ensure that you check for the relevant PID every time you perform this process.
  3. Execute the control-cpu-load script by using the following command:
    # sh control-cpu-load.sh
  4. When the system prompts you with the following input, type the PID of the daemon acquired from the previous step and press Enter:
    [root@XX-XX scripts]# sh control-cpu-load.sh
    Enter gluster daemon pid for which you want to control CPU.
    1565
  5. When the system prompts you with the following input, type y and press Enter:
    If you want to continue the script to attach 1565 with new cgroup_gluster_1565 cgroup Press (y/n)?
  6. When the system prompts the following notification, enter the required quota value to be assigned to the daemon and press Enter:
    Creating child cgroup directory 'cgroup_gluster_1565 cgroup' for daemon_name.service.
    Enter quota value in range [10,100]:
    25
    
    In this example, quota value for the daemon service is set to 25.
    The system displays the following message once the quota value has been successfully set:
    Entered quota value is 25
    Setting 25000 to cpu.cfs_quota_us for gluster_cgroup.
    Tasks are attached successfully specific to 1565 to cgroup_gluster_1565.

Important

Perform this procedure every time the daemon is restarted and has a new daemon PID.

Procedure 18.2. Controlling memory usage for a Gluster daemon

The control-mem script provides a utility to control memory utilization for any Gluster daemon by using the cgroup framework to configure memory limit for a process.
  1. Navigate to the scripts folder by using the following command:
    # cd /usr/share/glusterfs/scripts
  2. Determine the PID of the required gluster daemon by using the following command:
    # ps -aef | grep daemon_name
    The output will be in the following format:
    root      1565     1  0 Feb05 ?        00:09:17 /usr/sbin/glusterfs -s localhost --volfile-id gluster/daemon_name -p /var/run/gluster/daemon_name/daemon_name.pid -l /var/log/glusterfs/daemon_name.log -S /var/run/gluster/ed49b959a0dc9b2185913084e3b2b339.socket --xlator-option *replicate*.node-uuid=13dbfa1e-ebbf-4cee-a1ac-ca6763903c55
      root     16766 14420  0 19:00 pts/0    00:00:00 grep --color=auto daemon_name
    In this output, 1565 represents the PID of the daemon service.
  3. Execute the control-mem script by using the following command:
    # sh control-mem.sh
  4. When the system prompts for the following input, type the PID of the daemon acquired from the previous step and press Enter:
    [root@XX-XX scripts]# sh control-mem.sh
    Enter gluster daemon pid for which you want to control CPU.
    1565
    In this example, 1565 represents the PID of the daemon service. The PID of the daemon services can vary from system to system.
  5. When the system prompts for the following input, type y and press Enter:
    If you want to continue the script to attach daeomon with new cgroup. Press (y/n)?
    The system prompts the following notification:
    Creating child cgroup directory 'cgroup_gluster_1565 cgroup' for daemon_name.service.
  6. When the system prompts for the following input, enter the required memory value to be assigned to the daemon and press Enter:
    Enter Memory value in Mega bytes [100,8000000000000]:
    In this example, the memory value is set to 5000. The system prompts the following message once the memory value has been successfully set:
    Entered memory limit value is 5000.
    Setting 5242880000 to memory.limit_in_bytes for /sys/fs/cgroup/memory/system.slice/daemon_name.service/cgroup_gluster_1565.
    Tasks are attached successfully specific to 1565 to cgroup_gluster_1565.

Important

Perform this procedure every time the daemon is restarted and has a new daemon PID.

Chapter 19. Tuning for Performance

This chapter provides information on configuring Red Hat Gluster Storage and explains clear and simple activities that can improve system performance.

19.1. Disk Configuration

Red Hat Gluster Storage supports JBOD (Just a Bunch of Disks) and hardware RAID storage.

19.1.1. Hardware RAID

The RAID levels that are most commonly recommended are RAID 6 and RAID 10. RAID 6 provides better space efficiency, good read performance and good performance for sequential writes to large files.
When configured across 12 disks, RAID 6 can provide ~40% more storage space in comparison to RAID 10, which has a 50% reduction in capacity. However, RAID 6 performance for small file writes and random writes tends to be lower than RAID 10. If the workload is strictly small files, then RAID 10 is the optimal configuration.
An important parameter in hardware RAID configuration is the stripe unit size. With thin provisioned disks, the choice of RAID stripe unit size is closely related to the choice of thin-provisioning chunk size.
For RAID 10, a stripe unit size of 256 KiB is recommended.
For RAID 6, the stripe unit size must be chosen such that the full stripe size (stripe unit * number of data disks) is between 1 MiB and 2 MiB, preferably in the lower end of the range. Hardware RAID controllers usually allow stripe unit sizes that are a power of 2. For RAID 6 with 12 disks (10 data disks), the recommended stripe unit size is 128KiB.

19.1.2. JBOD

In the JBOD configuration, physical disks are not aggregated into RAID devices, but are visible as separate disks to the operating system. This simplifies system configuration by not requiring a hardware RAID controller.
If disks on the system are connected through a hardware RAID controller, refer to the RAID controller documentation on how to create a JBOD configuration; typically, JBOD is realized by exposing raw drives to the operating system using a pass-through mode.
In the JBOD configuration, a single physical disk serves as storage for a Red Hat Gluster Storage brick.
JBOD configurations support up to 36 disks per node with dispersed volumes and three-way replication.

19.2. Brick Configuration

Format bricks using the following configurations to enhance performance:

Procedure 19.1. Brick Configuration

  1. LVM layer

    The steps for creating a brick from a physical device is listed below. An outline of steps for creating multiple bricks on a physical device is listed as Example - Creating multiple bricks on a physical device below.
    • Creating the Physical Volume
      The pvcreate command is used to create the physical volume. The Logical Volume Manager can use a portion of the physical volume for storing its metadata while the rest is used as the data portion.Align the I/O at the Logical Volume Manager (LVM) layer using --dataalignment option while creating the physical volume.
      The command is used in the following format:
      # pvcreate --dataalignment alignment_value disk
      For JBOD, use an alignment value of 256K.
      In case of hardware RAID, the alignment_value should be obtained by multiplying the RAID stripe unit size with the number of data disks. If 12 disks are used in a RAID 6 configuration, the number of data disks is 10; on the other hand, if 12 disks are used in a RAID 10 configuration, the number of data disks is 6.
      For example, the following command is appropriate for 12 disks in a RAID 6 configuration with a stripe unit size of 128 KiB:
      # pvcreate --dataalignment 1280k disk
      The following command is appropriate for 12 disks in a RAID 10 configuration with a stripe unit size of 256 KiB:
      # pvcreate --dataalignment 1536k disk
      To view the previously configured physical volume settings for --dataalignment, run the following command:
      # pvs -o +pe_start /dev/sdb
        PV         VG   Fmt  Attr PSize PFree 1st PE
        /dev/sdb        lvm2 a--  9.09t 9.09t   1.25m
    • Creating the Volume Group
      The volume group is created using the vgcreate command.
      For hardware RAID, in order to ensure that logical volumes created in the volume group are aligned with the underlying RAID geometry, it is important to use the -- physicalextentsize option. Execute the vgcreate command in the following format:
      # vgcreate --physicalextentsize extent_size VOLGROUP physical_volume
      The extent_size should be obtained by multiplying the RAID stripe unit size with the number of data disks. If 12 disks are used in a RAID 6 configuration, the number of data disks is 10; on the other hand, if 12 disks are used in a RAID 10 configuration, the number of data disks is 6.
      For example, run the following command for RAID-6 storage with a stripe unit size of 128 KB, and 12 disks (10 data disks):
      # vgcreate --physicalextentsize 1280k VOLGROUP physical_volume
      In the case of JBOD, use the vgcreate command in the following format:
      # vgcreate VOLGROUP physical_volume
    • Creating the Thin Pool
      A thin pool provides a common pool of storage for thin logical volumes (LVs) and their snapshot volumes, if any.
      Execute the following commands to create a thin pool of a specific size:
      # lvcreate --thin VOLGROUP/POOLNAME --size POOLSIZE --chunksize CHUNKSIZE --poolmetadatasize METASIZE --zero n
      You can also create a thin pool of the maximum possible size for your device by executing the following command:
      # lvcreate --thin VOLGROUP/POOLNAME --extents 100%FREE --chunksize CHUNKSIZE --poolmetadatasize METASIZE --zero n

      Recommended parameter values for thin pool creation

      poolmetadatasize
      Internally, a thin pool contains a separate metadata device that is used to track the (dynamically) allocated regions of the thin LVs and snapshots. The poolmetadatasize option in the above command refers to the size of the pool metadata device.
      The maximum possible size for a metadata LV is 16 GiB. Red Hat Gluster Storage recommends creating the metadata device of the maximum supported size. You can allocate less than the maximum if space is a concern, but in this case you should allocate a minimum of 0.5% of the pool size.

      Warning

      If your metadata pool runs out of space, you cannot create data. This includes the data required to increase the size of the metadata pool or to migrate data away from a volume that has run out of metadata space. Monitor your metadata pool using the lvs -o+metadata_percent command and ensure that it does not run out of space.
      chunksize
      An important parameter to be specified while creating a thin pool is the chunk size,which is the unit of allocation. For good performance, the chunk size for the thin pool and the parameters of the underlying hardware RAID storage should be chosen so that they work well together.
      For JBOD, use a thin pool chunk size of 256 KiB.
      For RAID 6 storage, the striping parameters should be chosen so that the full stripe size (stripe_unit size * number of data disks) is between 1 MiB and 2 MiB, preferably in the low end of the range. The thin pool chunk size should be chosen to match the RAID 6 full stripe size. Matching the chunk size to the full stripe size aligns thin pool allocations with RAID 6 stripes, which can lead to better performance. Limiting the chunk size to below 2 MiB helps reduce performance problems due to excessive copy-on-write when snapshots are used.
      For example, for RAID 6 with 12 disks (10 data disks), stripe unit size should be chosen as 128 KiB. This leads to a full stripe size of 1280 KiB (1.25 MiB). The thin pool should then be created with the chunk size of 1280 KiB.
      For RAID 10 storage, the preferred stripe unit size is 256 KiB. This can also serve as the thin pool chunk size. Note that RAID 10 is recommended when the workload has a large proportion of small file writes or random writes. In this case, a small thin pool chunk size is more appropriate, as it reduces copy-on-write overhead with snapshots.
      If the addressable storage on the device is smaller than the device itself, you need to adjust the recommended chunk size. Calculate the adjustment factor using the following formula:
      adjustment_factor = device_size_in_tb / (preferred_chunk_size_in_kb * 4 / 64 )
      Round the adjustment factor up. Then calculate the new chunk size using the following:
      chunk_size = preferred_chunk_size * rounded_adjustment_factor
      block zeroing
      By default, the newly provisioned chunks in a thin pool are zeroed to prevent data leaking between different block devices. In the case of Red Hat Gluster Storage, where data is accessed via a file system, this option can be turned off for better performance with the --zero n option. Note that n does not need to be replaced.
      The following example shows how to create the thin pool:
      # lvcreate --thin VOLGROUP/thin_pool --size 2T --chunksize 1280k --poolmetadatasize 16G --zero n
      You can also use --extents 100%FREE to ensure the thin pool takes up all available space once the metadata pool is created.
      # lvcreate --thin VOLGROUP/thin_pool --extents 100%FREE --chunksize 1280k --poolmetadatasize 16G --zero n
      The following example shows how to create a 2 TB thin pool:
      # lvcreate --thin VOLGROUP/thin_pool --size 2T --chunksize 1280k --poolmetadatasize 16G --zero n
      The following example creates a thin pool that takes up all remaining space once the metadata pool has been created.
      # lvcreate --thin VOLGROUP/thin_pool --extents 100%FREE --chunksize 1280k --poolmetadatasize 16G --zero n
    • Creating a Thin Logical Volume
      After the thin pool has been created as mentioned above, a thinly provisioned logical volume can be created in the thin pool to serve as storage for a brick of a Red Hat Gluster Storage volume.
      # lvcreate --thin --name LV_name --virtualsize LV_size VOLGROUP/thin_pool
    • Example - Creating multiple bricks on a physical device
      The steps above (LVM Layer) cover the case where a single brick is being created on a physical device. This example shows how to adapt these steps when multiple bricks need to be created on a physical device.

      Note

      In this following steps, we are assuming the following:
      • Two bricks must be created on the same physical device
      • One brick must be of size 4 TiB and the other is 2 TiB
      • The device is /dev/sdb, and is a RAID-6 device with 12 disks
      • The 12-disk RAID-6 device has been created according to the recommendations in this chapter, that is, with a stripe unit size of 128 KiB
      1. Create a single physical volume using pvcreate
        # pvcreate --dataalignment 1280k /dev/sdb
      2. Create a single volume group on the device
        # vgcreate --physicalextentsize 1280k vg1 /dev/sdb
      3. Create a separate thin pool for each brick using the following commands:
        # lvcreate --thin vg1/thin_pool_1 --size 4T --chunksize 1280K --poolmetadatasize 16G --zero n
        # lvcreate --thin vg1/thin_pool_2 --size 2T --chunksize 1280K --poolmetadatasize 16G --zero n
        In the examples above, the size of each thin pool is chosen to be the same as the size of the brick that will be created in it. With thin provisioning, there are many possible ways of managing space, and these options are not discussed in this chapter.
      4. Create a thin logical volume for each brick
        # lvcreate --thin --name lv1 --virtualsize 4T vg1/thin_pool_1
        # lvcreate --thin --name lv2 --virtualsize 2T vg1/thin_pool_2
      5. Follow the XFS Recommendations (next step) in this chapter for creating and mounting filesystems for each of the thin logical volumes
        # mkfs.xfs options /dev/vg1/lv1
        # mkfs.xfs options /dev/vg1/lv2
        # mount options /dev/vg1/lv1 mount_point_1
        # mount options /dev/vg1/lv2 mount_point_2
  2. XFS Recommendataions

    • XFS Inode Size
      As Red Hat Gluster Storage makes extensive use of extended attributes, an XFS inode size of 512 bytes works better with Red Hat Gluster Storage than the default XFS inode size of 256 bytes. So, inode size for XFS must be set to 512 bytes while formatting the Red Hat Gluster Storage bricks. To set the inode size, you have to use -i size option with the mkfs.xfs command as shown in the following Logical Block Size for the Directory section.
    • XFS RAID Alignment
      When creating an XFS file system, you can explicitly specify the striping parameters of the underlying storage in the following format:
      # mkfs.xfs other_options -d su=stripe_unit_size,sw=stripe_width_in_number_of_disks device
      For RAID 6, ensure that I/O is aligned at the file system layer by providing the striping parameters. For RAID 6 storage with 12 disks, if the recommendations above have been followed, the values must be as following:
      # mkfs.xfs other_options -d su=128k,sw=10 device
      For RAID 10 and JBOD, the -d su=<>,sw=<> option can be omitted. By default, XFS will use the thin-p chunk size and other parameters to make layout decisions.
    • Logical Block Size for the Directory
      An XFS file system allows to select a logical block size for the file system directory that is greater than the logical block size of the file system. Increasing the logical block size for the directories from the default 4 K, decreases the directory I/O, which in turn improves the performance of directory operations. To set the block size, you need to use -n size option with the mkfs.xfs command as shown in the following example output.
      Following is the example output of RAID 6 configuration along with inode and block size options:
      # mkfs.xfs -f -i size=512 -n size=8192 -d su=128k,sw=10 logical volume
      meta-data=/dev/mapper/gluster-brick1 isize=512    agcount=32, agsize=37748736 blks
               =    sectsz=512   attr=2, projid32bit=0
      data     =     bsize=4096   blocks=1207959552, imaxpct=5
               =    sunit=32     swidth=320 blks
      naming   = version 2   bsize=8192   ascii-ci=0
      log      =internal log   bsize=4096   blocks=521728, version=2
               =    sectsz=512   sunit=32 blks, lazy-count=1
      realtime =none    extsz=4096   blocks=0, rtextents=0
    • Allocation Strategy
      inode32 and inode64 are two most common allocation strategies for XFS. With inode32 allocation strategy, XFS places all the inodes in the first 1 TiB of disk. With larger disk, all the inodes would be stuck in first 1 TiB. inode32 allocation strategy is used by default.
      With inode64 mount option inodes would be replaced near to the data which would be minimize the disk seeks.
      To set the allocation strategy to inode64 when file system is being mounted, you need to use -o inode64 option with the mount command as shown in the following Access Time section.
    • Access Time
      If the application does not require to update the access time on files, than file system must always be mounted with noatime mount option. For example:
      # mount -t xfs -o inode64,noatime <logical volume> <mount point>
      This optimization improves performance of small-file reads by avoiding updates to the XFS inodes when files are read.
      /etc/fstab entry for option E + F
       <logical volume> <mount point>xfs     inode64,noatime   0 0
    • Allocation groups
      Each XFS file system is partitioned into regions called allocation groups. Allocation groups are similar to the block groups in ext3, but allocation groups are much larger than block groups and are used for scalability and parallelism rather than disk locality. The default allocation for an allocation group is 1 TiB.
      Allocation group count must be large enough to sustain the concurrent allocation workload. In most of the cases allocation group count chosen by mkfs.xfs command would give the optimal performance. Do not change the allocation group count chosen by mkfs.xfs, while formatting the file system.
    • Percentage of space allocation to inodes
      If the workload is very small files (average file size is less than 10 KB ), then it is recommended to set maxpct value to 10, while formatting the file system. Also, maxpct value can be set upto 100 if needed for arbiter brick.
  3. Performance tuning option in Red Hat Gluster Storage

    A tuned profile is designed to improve performance for a specific use case by tuning system parameters appropriately. Red Hat Gluster Storage includes tuned profiles tailored for its workloads. These profiles are available in both Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux 7.

    Table 19.1. Recommended Profiles for Different Workloads

    WorkloadProfile Name
    Large-file, sequential I/O workloads rhgs-sequential-io
    Small-file workloads rhgs-random-io
    Random I/O workloads rhgs-random-io
    Earlier versions of Red Hat Gluster Storage on Red Hat Enterprise Linux 6 recommended tuned profiles rhs-high-throughput and rhs-virtualization. These profiles are still available on Red Hat Enterprise Linux 6. However, switching to the new profiles is recommended.

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
    To apply tunings contained in the tuned profile, run the following command after creating a Red Hat Gluster Storage volume.
    # tuned-adm profile profile-name
    For example:
    # tuned-adm profile rhgs-sequential-io
  4. Writeback Caching

    For small-file and random write performance, we strongly recommend writeback cache, that is, non-volatile random-access memory (NVRAM) in your storage controller. For example, normal Dell and HP storage controllers have it. Ensure that NVRAM is enabled, that is, the battery is working. Refer your hardware documentation for details on enabling NVRAM.
    Do not enable writeback caching in the disk drives, this is a policy where the disk drive considers the write is complete before the write actually made it to the magnetic media (platter). As a result, the disk write cache might lose its data during a power failure or even loss of metadata leading to file system corruption.

19.2.1. Many Bricks per Node

By default, for every brick configured on a Red Hat Gluster Storage server node, one process is created and one port is consumed. If you have a large number of bricks configured on a single server, enabling brick multiplexing reduces port and memory consumption by allowing compatible bricks to use the same process and port. Red Hat recommends restarting all volumes after enabling or disabling brick multiplexing.
As of Red Hat Gluster Storage 3.4, brick multiplexing is supported only for OpenShift Container Storage use cases.

Configuring Brick Multiplexing

  1. Set cluster.brick-multiplex to on. This option affects all volumes.
    # gluster volume set all cluster.brick-multiplex on
  2. Restart all volumes for brick multiplexing to take effect.
    # gluster volume stop VOLNAME
    # gluster volume start VOLNAME

Important

Brick compatibility is determined when the volume starts, and depends on volume options shared between bricks. When brick multiplexing is enabled, Red Hat recommends restarting the volume whenever any volume configuration details are changed in order to maintain the compatibility of the bricks grouped under a single process.

19.2.2. Port Range Configuration

By default, for every brick configured on a Red Hat Gluster Storage server node, one process is created and one port is consumed. If you have a large number of bricks configured on a single server, configuring port range lets you control the range of ports allocated by glusterd to newly created or existing bricks and volumes.
This can be achieved with the help of the glusterd.vol file. The base-port and max-port options can be used to set the port range. By default, base-port is set to 49152, and max-port is set to 60999.

Important

If glusterd runs out of free ports to allocate within the specified range of base-port and max-port, newer bricks and volumes fail to start.

Configuring Port Range

  1. Edit the glusterd.vol file on all the nodes.
    # vi /etc/glusterfs/glusterd.vol
  2. Remove the comment marker # corresponding to the base-port and max-port options.
    volume management
        type mgmt/glusterd
        option working-directory /var/lib/glusterd
        option transport-type socket,rdma
        option transport.socket.keepalive-time 10
        option transport.socket.keepalive-interval 2
        option transport.socket.read-fail-log off
        option ping-timeout 0
        option event-threads 1
    #   option lock-timer 180
    #   option transport.address-family inet6
        option base-port 49152
        option max-port  60999
    end-volume
    
  3. Define the port number in the base-port, and max-port options.
       option base-port 49152
       option max-port  60999
    
  4. Save the glusterd.vol file and restart the glusterd service on each Red Hat Gluster Storage node.

19.3. Network

Data traffic Network becomes a bottleneck as and when number of storage nodes increase. By adding a 10GbE or faster network for data traffic, you can achieve faster per node performance. Jumbo frames must be enabled at all levels, that is, client, Red Hat Gluster Storage node, and ethernet switch levels. MTU of size N+208 must be supported by ethernet switch where N=9000. We recommend you to have a separate network for management and data traffic when protocols like NFS /CIFS are used instead of native client. Preferred bonding mode for Red Hat Gluster Storage client is mode 6 (balance-alb), this allows client to transmit writes in parallel on separate NICs much of the time.

19.4. Memory

Red Hat Gluster Storage does not consume significant compute resources from the storage nodes themselves. However, read intensive workloads can benefit greatly from additional RAM.

19.4.1. Virtual Memory Parameters

The data written by the applications is aggregated in the operating system page cache before being flushed to the disk. The aggregation and writeback of dirty data is governed by the Virtual Memory parameters. The following parameters may have a significant performance impact:
  • vm.dirty_ratio
  • vm.dirty_background_ratio
The appropriate values of these parameters vary with the type of workload:
  • Large-file sequential I/O workloads benefit from higher values for these parameters.
  • For small-file and random I/O workloads it is recommended to keep these parameter values low.
The Red Hat Gluster Storage tuned profiles set the values for these parameters appropriately. Hence, it is important to select and activate the appropriate Red Hat Gluster Storage profile based on the workload.

19.5. Small File Performance Enhancements

The ratio of the time taken to perform operations on the metadata of a file to performing operations on its data determines the difference between large files and small files. Metadata-intensive workload is the term used to identify such workloads. A few performance enhancements can be made to optimize the network and storage performance and minimize the effect of slow throughput and response time for small files in a Red Hat Gluster Storage trusted storage pool.

Note

For a small-file workload, activate the rhgs-random-io tuned profile.
Configuring Threads for Event Processing

You can set the client.event-thread and server.event-thread values for the client and server components. Setting the value to 4, for example, would enable handling four network connections simultaneously.

Setting the event threads value for a client
You can tune the Red Hat Gluster Storage Server performance by tuning the event thread values.
# gluster volume set VOLNAME client.event-threads <value>

Example 19.1. Tuning the event threads for a client accessing a volume

# gluster volume set test-vol client.event-threads 4
Setting the event thread value for a server
You can tune the Red Hat Gluster Storage Server performance using event thread values.
# gluster volume set VOLNAME server.event-threads <value>

Example 19.2. Tuning the event threads for a server accessing a volume

# gluster volume set test-vol server.event-threads 4
Verifying the event thread values
You can verify the event thread values that are set for the client and server components by executing the following command:
# gluster volume info VOLNAME
See topic, Configuring Volume Options for information on the minimum, maximum, and default values for setting these volume options.
Best practices to tune event threads

It is possible to see performance gains with the Red Hat Gluster Storage stack by tuning the number of threads processing events from network connections. The following are the recommended best practices to tune the event thread values.

  1. As each thread processes a connection at a time, having more threads than connections to either the brick processes (glusterfsd) or the client processes (glusterfs or gfapi) is not recommended. Due to this reason, monitor the connection counts (using the netstat command) on the clients and on the bricks to arrive at an appropriate number for the event thread count.
  2. Configuring a higher event threads value than the available processing units could again cause context switches on these threads. As a result reducing the number deduced from the previous step to a number that is less that the available processing units is recommended.
  3. If a Red Hat Gluster Storage volume has a high number of brick processes running on a single node, then reducing the event threads number deduced in the previous step would help the competing processes to gain enough concurrency and avoid context switches across the threads.
  4. If a specific thread consumes more number of CPU cycles than needed, increasing the event thread count would enhance the performance of the Red Hat Gluster Storage Server.
  5. In addition to the deducing the appropriate event-thread count, increasing the server.outstanding-rpc-limit on the storage nodes can also help to queue the requests for the brick processes and not let the requests idle on the network queue.
  6. Another parameter that could improve the performance when tuning the event-threads value is to set the performance.io-thread-count (and its related thread-counts) to higher values, as these threads perform the actual IO operations on the underlying file system.

19.5.1. Enabling Lookup Optimization

Distribute xlator (DHT) has a performance penalty when it deals with negative lookups. Negative lookups are lookup operations for entries that does not exist in the volume. A lookup for a file/directory that does not exist is a negative lookup.
Negative lookups are expensive and typically slows down file creation, as DHT attempts to find the file in all sub-volumes. This especially impacts small file performance, where a large number of files are being added/created in quick succession to the volume.
The negative lookup fan-out behavior can be optimized by not performing the same in a balanced volume.
The cluster.lookup-optimize configuration option enables DHT lookup optimization. To enable this option run the following command:
# gluster volume set VOLNAME cluster.lookup-optimize <on/off>\

Note

The configuration takes effect for newly created directories immediately post setting the above option. For existing directories, a rebalance is required to ensure the volume is in balance before DHT applies the optimization on older directories.

19.6. Replication

If a system is configured for two ways, active-active replication, write throughput will generally be half of what it would be in a non-replicated configuration. However, read throughput is generally improved by replication, as reads can be delivered from either storage node.

19.7. Directory Operations

In order to improve the performance of directory operations of Red Hat Gluster Storage volumes, the maximum metadata (stat, xattr) caching time on the client side is increased to 10 minutes, without compromising on the consistency of the cache.
Significant performance improvements can be achieved in the following workloads by enabling metadata caching:
  • Listing of directories (recursive)
  • Creating files
  • Deleting files
  • Renaming files

19.7.1. Enabling Metadata Caching

Enable metadata caching to improve the performance of directory operations. Execute the following commands from any one of the nodes on the trusted storage pool in the order mentioned below.

Note

If majority of the workload is modifying the same set of files and directories simultaneously from multiple clients, then enabling metadata caching might not provide the desired performance improvement.
  1. Execute the following command to enable metadata caching and cache invalidation:
    # gluster volume set <volname> group metadata-cache
    This is group set option which sets multiple volume options in a single command.
  2. To increase the number of files that can be cached, execute the following command:
    # gluster volume set <VOLNAME> network.inode-lru-limit <n>
    n, is set to 50000. It can be increased if the number of active files in the volume is very high. Increasing this number increases the memory footprint of the brick processes.

19.8. LVM Cache for Red Hat Gluster Storage

Important

LVM Cache must be used with Red Hat Gluster Storage only on Red Hat Enterprise Linux 7.4 or later. This release includes a number of fixes and enhancements that are critical to a positive experience with caching.

19.8.1. About LVM Cache

An LVM Cache logical volume (LV) can be used to improve the performance of a block device by attaching to it a smaller and much faster device to act as a data acceleration layer. When a cache is attached to an LV, the Linux kernel subsystems attempt to keep 'hot' data copies in the fast cache layer at the block level. Additionally, as space in the cache allows, writes are made initially to the cache layer. The results can be better Input/Output (I/O) performance improvements for many workloads.

19.8.1.1. LVM Cache vs. DM-Cache

dm-cache refers to the Linux kernel-level device-mapper subsystem that is responsible for all I/O transactions. For most usual operations, the administrator interfaces with the logical volume manager (LVM) as a much simpler abstraction layer above device-mapper. As such, lvmcache is simply part of the LVM system acting as an abstraction layer for the dm-cache subsystem.

19.8.1.2. LVM Cache vs. Gluster Tiered Volumes

Red Hat Gluster Storage supports tiered volumes, which are often configured with the same type of fast devices backing the fast tier bricks. The operation of tiering is at the file level and is distributed across the trusted storage pool (TSP). These tiers operate by moving files between the tiers based on tunable algorithms, such that files are migrated between tiers rather than copied.
In contrast, LVM Cache operates locally at each block device backing the bricks and does so at the block level. LVM Cache stores copies of the hot data in the fast layer using a non-tunable algorithm (though chunk sizes may be tuned for optimal performance).
For most workloads, LVM Cache tends to offer greater performance compared to tiering. However, for certain types of workloads where a large number of clients are consistently accessing the same hot file data set, or where writes can consistently go to the hot tier, tiering may prove more beneficial than LVM Cache.

19.8.1.3. Arbiter Bricks

Arbiter bricks operate by storing all file metadata transactions but not data transactions in order to prevent split-brain problems without the overhead of a third data copy. It is important to understand that file metadata is stored with the file, and so arbiter bricks effectively store empty copies of all files.
In a distributed system such as Red Hat Gluster Storage, latency can greatly affect the performance of file operations, especially when files are very small and file-based transactions are very high. With such small files, the overhead of the metadata latency can be more impactful to performance than the throughput of the I/O subsystems. Therefore, it is important when creating arbiter bricks that the backing storage devices be as fast as the fastest data storage devices. Therefore, when using LVM Cache to accelerate your data volumes with fast devices, you must allocate the same class of fast devices to serve as your arbiter brick backing devices, otherwise your slow arbiter bricks could negate the performance benefits of your cache-accelerated data bricks.

19.8.1.4. Writethrough vs. Writeback

LVM Cache can operate in either writethrough or writeback mode, with writethrough being the default. In writethrough mode, any data written is stored both in the cache layer and in the main data layer. The loss of a device associated with the cache layer in this case would not mean the loss of any data.
Writeback mode delays the writing of data blocks from the cache layer to the main data layer. This mode can increase write performance, but the loss of a device associated with the cache layer can result in lost data locally.

Note

Data resiliency protects from global data loss in the case of a writeback cache device failure under most circumstances, but edge cases could lead to inconsistent data that cannot be automatically healed.

19.8.1.5. Cache-Friendly Workloads

While LVM Cache has been demonstrated to improve performance for Red Hat Gluster Storage under many use cases, the relative effects vary based on the workload. The benefits of block-based caching means that LVM Cache can be efficient for even larger file workloads. However, some workloads may see little-to-no benefit from LVM Cache, and highly-random workloads or those with very large working sets may even experience a performance degradation. It is highly recommended that you understand your workload and test accordingly before making a significant investment in hardware to accelerate your storage workload.

19.8.2. Choosing the Size and Speed of Your Cache Devices

Sizing a cache appropriately to a workload can be a complicated study, particularly in Red Hat Gluster Storage where the cache is local to the bricks rather than global to the volume. In general, you want to understand the size of your working set as a percentage of your total data set and then size your cache layer with some headroom (10-20%) beyond that working set size to allow for efficient flushes and room to cache new writes. Optimally, the entire working set is kept in the cache, and the overall performance you experience is near that of storing your data directly on the fast devices.
When heavily stressed by a working set that is not well-suited for the cache size, you will begin to see a higher percentage of cache misses and your performance will be inconsistent. You may find that as this cache-to-data imbalance increases, a higher percentage of data operations will drop to the speed of the slower data device. From the perspective of a user, this can sometimes be more frustrating than a device that is consistently slow. Understanding and testing your own workload is essential to making an appropriate cache sizing decision.
When choosing your cache devices, always consider high-endurance enterprise-class drives. These are typically tuned to either read or write intensive workloads, so be sure to inspect the hardware performance details when making your selection. Pay close attention to latency alongside IOPS or throughput, as the high transaction activity of a cache will benefit significantly from lower-latency hardware. When possible, select NVMe devices that use the PCI bus directly rather than SATA/SAS devices, as this will additionally benefit latency.

19.8.3. Configuring LVM Cache

A cache pool is created using logical volume manager (LVM) with fast devices as the physical volumes (PVs). The cache pool is then attached to an existing thin pool (TP) or thick logical volume (LV). Once this is done, block-level caching is immediately enabled for the configured LV, and the dm-cache algorithms will work to keep hot copies of data on the cache pool sub-volume.

Warning

Adding or removing cache pools can be done on active volumes, even with mounted filesystems in use. However, there is overhead to the operation and performance impacts will be seen, especially when removing a cache volume in writeback mode, as a full data sync will need to occur. As with any changes to the I/O stack, there is risk of data loss. All changes must be made with the requisite caution.
In the following example commands, we assume the use of a high-performance NVMe PCI device for caching. These devices typically present with device file paths such as /dev/nvme0n1. A SATA/SAS device will likely present with a device path such as /dev/sdb. The following example naming has been used:
  • Physical Volume (PV) Name: /dev/nvme0n1
  • Volume Group (VG) Name: GVG
  • Thin pool name: GTP
  • Logical Volume (LV) name: GLV

Note

There are several different ways to configure LVM Cache. Following is the most simple approach applicable to most use cases. For details and further command examples, see lvmcache(7).
  1. Create a PV for your fast data device.
    # pvcreate /dev/nvme0n1
  2. Add the fast data PV to the VG that hosts the LV you intend to cache.
    # vgextend GVG /dev/nvme0n1
  3. Create the cache pool from your fast data device, reserving space required for metadata during the cache conversion process of your LV.
    # lvcreate --type cache-pool -l 100%FREE -n cpool GVG /dev/nvme0n1
  4. Convert your existing data thin pool LV into a cache LV.
    # lvconvert --type cache --cachepool GVG/cpool GVG/GTP

19.8.4. Managing LVM Cache

19.8.4.1. Changing the Mode of an Existing Cache Pool

An existing cache LV can be converted between writethrough and writeback modes with the lvchange command. For thin LVs, the command must be run against the tdata subvolume.
# lvchange --cachemode writeback GVG/GTP_tdata

19.8.4.2. Checking Your Configuration

Use the lsblk command to view the new virtual block device layout.
# lsblk /dev/{sdb,nvme0n1}
NAME                              MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb                                 8:16   0   9.1T  0 disk
└─GVG-GTP_tdata_corig 253:9    0   9.1T  0 lvm
  └─GVG-GTP_tdata     253:3    0   9.1T  0 lvm
    └─GVG-GTP-tpool   253:4    0   9.1T  0 lvm
      ├─GVG-GTP       253:5    0   9.1T  0 lvm
      └─GVG-GLV       253:6    0   9.1T  0 lvm  /mnt
nvme0n1                           259:0    0 745.2G  0 disk
├─GVG-GTP_tmeta       253:2    0    76M  0 lvm
│ └─GVG-GTP-tpool     253:4    0   9.1T  0 lvm
│   ├─GVG-GTP         253:5    0   9.1T  0 lvm
│   └─GVG-GLV         253:6    0   9.1T  0 lvm  /mnt
├─GVG-cpool_cdata           253:7    0 701.1G  0 lvm
│ └─GVG-GTP_tdata     253:3    0   9.1T  0 lvm
│   └─GVG-GTP-tpool   253:4    0   9.1T  0 lvm
│     ├─GVG-GTP       253:5    0   9.1T  0 lvm
│     └─GVG-GLV       253:6    0   9.1T  0 lvm  /mnt
├─GVG-cpool_cmeta           253:8    0    48M  0 lvm
│ └─GVG-GTP_tdata     253:3    0   9.1T  0 lvm
│   └─GVG-GTP-tpool   253:4    0   9.1T  0 lvm
│     ├─GVG-GTP       253:5    0   9.1T  0 lvm
│     └─GVG-GLV       253:6    0   9.1T  0 lvm  /mnt
└─GVG-GTP_tdata_corig 253:9    0   9.1T  0 lvm
  └─GVG-GTP_tdata     253:3    0   9.1T  0 lvm
    └─GVG-GTP-tpool   253:4    0   9.1T  0 lvm
      ├─GVG-GTP       253:5    0   9.1T  0 lvm
      └─GVG-GLV       253:6    0   9.1T  0 lvm  /mnt
The lvs command displays a number of valuable columns to show the status of your cache pool and volume. For more details, see lvs(8).
# lvs -a -o name,vg_name,size,pool_lv,devices,cachemode,chunksize
LV                      VG          LSize  Pool      Devices                  CacheMode    Chunk
GLV               GVG    9.10t GTP                                       0
GTP               GVG   <9.12t           GTP_tdata(0)                    8.00m
[GTP_tdata]       GVG   <9.12t [cpool]   GTP_tdata_corig(0) writethrough 736.00k
[GTP_tdata_corig] GVG   <9.12t           /dev/sdb(0)                           0
[GTP_tdata_corig] GVG   <9.12t           /dev/nvme0n1(185076)                  0
[GTP_tmeta]       GVG   76.00m           /dev/nvme0n1(185057)                  0
[cpool]                 GVG <701.10g           cpool_cdata(0)           writethrough 736.00k
[cpool_cdata]           GVG <701.10g           /dev/nvme0n1(24)                      0
[cpool_cmeta]           GVG   48.00m           /dev/nvme0n1(12)                      0
[lvol0_pmspare]         GVG   76.00m           /dev/nvme0n1(0)                       0
[lvol0_pmspare]         GVG   76.00m           /dev/nvme0n1(185050)                  0
root                    vg_root     50.00g           /dev/sda3(4095)                       0
swap                    vg_root    <16.00g           /dev/sda3(0)                          0
Some of the useful columns from the lvs command that can be used to monitor the effectiveness of the cache and to aid in sizing decisions are:
  • CacheTotalBlocks
  • CacheUsedBlocks
  • CacheDirtyBlocks
  • CacheReadHits
  • CacheReadMisses
  • CacheWriteHits
  • CacheWriteMisses
You will see a high ratio of Misses to Hits when the cache is cold (freshly attached to the LV). However, with a warm cache (volume online and transacting data for a sufficiently long period of time), high ratios here are indicative of an undersized cache device.
# lvs -a -o devices,cachetotalblocks,cacheusedblocks, \
cachereadhits,cachereadmisses | egrep 'Devices|cdata'

Devices                  CacheTotalBlocks  CacheUsedBlocks    CacheReadHits    CacheReadMisses
cpool_cdata(0)                     998850             2581                1                192

19.8.4.3. Detaching a Cache Pool

You can split a cache pool from an LV in one command, leaving the data LV in an un-cached state with all data intact and the cache pool still existing but unattached. In writeback mode this can take a long time to complete while all data is synced. This may also negatively impact performance while it is running.
# lvconvert --splitcache GVG/cpool

Part VI. Security

Chapter 20. Configuring Network Encryption in Red Hat Gluster Storage

Network encryption is the process of converting data into a cryptic format or code so that it can be securely transmitted on a network. Encryption prevents unauthorized use of the data.
Red Hat Gluster Storage supports network encryption using TLS/SSL. When network encryption is enabled, Red Hat Gluster Storage uses TLS/SSL for authentication and authorization, in place of the authentication framework that is used for non-encrypted connections. The following types of encryption are supported:
I/O encryption
Encryption of the I/O connections between the Red Hat Gluster Storage clients and servers.
Management encryption
Encryption of management (glusterd) connections within a trusted storage pool, and between glusterd and NFS Ganesha or SMB clients.
Network encryption is configured in the following files:
/etc/ssl/glusterfs.pem
Certificate file containing the system's uniquely signed TLS certificate. This file is unique for each system and must not be shared with others.
/etc/ssl/glusterfs.key
This file contains the system's unique private key. This file must not be shared with others.
/etc/ssl/glusterfs.ca
This file contains the certificates of the Certificate Authorities (CA) who have signed the certificates. The glusterfs.ca file must be identical on all servers in the trusted pool, and must contain the certificates of the signing CA for all servers and all clients. All clients should also have a .ca file that contains the certificates of the signing CA for all the servers.
Red Hat Gluster Storage does not use the global CA certificates that come with the system, so you need to either create your own self-signed certificates, or create certificates and have them signed by a Certificate Authority. If you are using self-signed certificates, the CA file for the servers is a concatenation of the relevant .pem files of every server and every client. The client CA file is a concatenation of the certificate files of every server.
/var/lib/glusterd/secure-access
This file is required for management encryption. It enables encryption on the management (glusterd) connections between glusterd of all servers and the connection between clients, and contains any configuration required by the Certificate Authority. The glusterd service of all servers uses this file to fetch volfiles and notify the clients with the volfile changes. This file must be present on all servers and all clients for management encryption to work correctly. It can be empty, but most configurations require at least one line to set the certificate depth (transport.socket.ssl-cert-depth) required by the Certificate Authority.

20.1. Preparing Certificates

To configure network encryption, each server and client needs a signed certificate and a private key. There are two options for certificates.
Self-signed certificate
Generating and signing the certificate yourself.
Certificate Authority (CA) signed certificate
Generating the certificate and then requesting that a Certificate Authority sign it.
Both of these options ensure that data transmitted over the network cannot be accessed by a third party, but certificates signed by a Certificate Authority imply an added level of trust and verification to a customer using your storage.

Procedure 20.1. Preparing a self-signed certificate

  1. Generate and sign certificates for each server and client

    Perform the following steps on each server and client.
    1. Generate a private key for this machine

      # openssl genrsa -out /etc/ssl/glusterfs.key 2048
    2. Generate a self-signed certificate for this machine

      The following command generates a signed certificate that expires in 365 days, instead of the default 30 days. Provide a short name for this machine in place of COMMONNAME. This is generally a hostname, FQDN, or IP address.
      # openssl req -new -x509 -key /etc/ssl/glusterfs.key -subj "/CN=COMMONNAME" -days 365 -out /etc/ssl/glusterfs.pem
  2. Generate client-side certificate authority lists

    From the first server, concatenate the /etc/ssl/glusterfs.pem files from all servers into a single file called glusterfs.ca, and place this file in the /etc/ssl directory on all clients.
    For example, running the following commands from server1 creates a certificate authority list (.ca file) that contains the certificates (.pem files) of two servers, and copies the certificate authority list (.ca file) to three clients.
    # cat /etc/ssl/glusterfs.pem > /etc/ssl/glusterfs.ca
    # ssh user@server2 cat /etc/ssl/glusterfs.pem >> /etc/ssl/glusterfs.ca
    # scp /etc/ssl/glusterfs.ca client1:/etc/ssl/glusterfs.ca
    # scp /etc/ssl/glusterfs.ca client2:/etc/ssl/glusterfs.ca
    # scp /etc/ssl/glusterfs.ca client3:/etc/ssl/glusterfs.ca
  3. Generate server-side glusterfs.ca files

    From the first server, append the certificates (/etc/ssl/glusterfs.pem files) from all clients to the end of the certificate authority list (/etc/ssl/glusterfs.ca file) generated in the previous step.
    For example, running the following commands from server1 appends the certificates (.pem files) of three clients to the certificate authority list (.ca file) on server1, and then copies that certificate authority list (.ca file) to one other server.
    # ssh user@client1 cat /etc/ssl/glusterfs.pem >> /etc/ssl/glusterfs.ca
    # ssh user@client2 cat /etc/ssl/glusterfs.pem >> /etc/ssl/glusterfs.ca
    # ssh user@client3 cat /etc/ssl/glusterfs.pem >> /etc/ssl/glusterfs.ca
    # scp /etc/ssl/glusterfs.ca server2:/etc/ssl/glusterfs.ca
  4. Verify server certificates

    Run the following command in the /etc/ssl directory on the servers to verify the certificate on that machine against the Certificate Authority list.
    # openssl verify -verbose -CAfile glusterfs.ca glusterfs.pem
    Your certificate is correct if the output of this command is glusterfs.pem: OK.

    Note

    This process does not work for self-signed client certificates.

Procedure 20.2. Preparing a Common Certificate Authority certificate

Perform the following steps on each server and client you wish to authorize.
  1. Generate a private key

    # openssl genrsa -out /etc/ssl/glusterfs.key 2048
  2. Generate a certificate signing request

    The following command generates a certificate signing request for a certificate that expires in 365 days, instead of the default 30 days. Provide a short name for this machine in place of COMMONNAME. This is generally a hostname, FQDN, or IP address.
    # openssl req -new -sha256 -key /etc/ssl/glusterfs.key -subj '/CN=<COMMONNAME>' -days 365 -out glusterfs.csr
  3. Send the generated glusterfs.csr file to your Certificate Authority

    Your Certificate Authority provides a signed certificate for this machine in the form of a .pem file, and the certificates of the Certificate Authority in the form of a .ca file.
  4. Place the .pem file provided by the Certificate Authority

    Ensure that the .pem file is called glusterfs.pem. Place this file in the /etc/ssl directory of this server only.
  5. Place the .ca file provided by the Certificate Authority

    Ensure that the .ca file is called glusterfs.ca. Place the .ca file in the /etc/ssl directory of all servers.
  6. Verify your certificates

    Run the following command in the /etc/ssl directory on all clients and servers to verify the certificate on that machine against the Certificate Authority list.
    # openssl verify -verbose -CAfile glusterfs.ca glusterfs.pem
    Your certificate is correct if the output of this command is glusterfs.pem: OK.

20.2. Configuring Network Encryption for a New Trusted Storage Pool

Follow this section to configure I/O and management encryption on a freshly installed Red Hat Gluster Storage deployment that does not yet have a trusted storage pool configured.

20.2.1. Enabling Management Encryption

Red Hat recommends enabling both management and I/O encryption, but if you only want to use I/O encryption, you can skip this section and continue with Section 20.2.2, “Enabling I/O Encryption”.

Procedure 20.3. Enabling management encryption on servers

Perform the following steps on all servers.
  1. Create and edit the secure-access file

    Create a new /var/lib/glusterd/secure-access file. This file can be empty if you are using the default settings.
    # touch /var/lib/glusterd/secure-access
    Your Certificate Authority may require changes to the SSL certificate depth setting, transport.socket.ssl-cert-depth, in order to work correctly. To edit this setting, add the following line to the secure-access file, replacing n with the certificate depth required by your Certificate Authority.
    echo "option transport.socket.ssl-cert-depth n" > /var/lib/glusterd/secure-access
  2. Start glusterd

    On Red Hat Enterprise Linux 7 based servers, run:
    # systemctl start glusterd
    On Red Hat Enterprise Linux 6 based servers, run:
    # service glusterd start

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  3. Continue storage configuration

    Proceed with the normal configuration process by setting up the trusted storage pool, formatting bricks, and creating volumes. For more information, see Chapter 4, Adding Servers to the Trusted Storage Pool and Chapter 5, Setting Up Storage Volumes.

Procedure 20.4. Enabling management encryption on clients

Prerequisites

Perform the following steps on all clients.
  1. Create and edit the secure-access file

    Create the /var/lib/glusterd directory, and create a new /var/lib/glusterd/secure-access file. This file can be empty if you are using the default settings.
    # touch /var/lib/glusterd/secure-access
    Your Certificate Authority may require changes to the SSL certificate depth setting, transport.socket.ssl-cert-depth, in order to work correctly. To edit this setting, add the following line to the secure-access file, replacing n with the certificate depth required by your Certificate Authority.
    echo "option transport.socket.ssl-cert-depth n" > /var/lib/glusterd/secure-access
  2. Start the volume

    On the server, start the volume.
    # gluster volume start volname
  3. Mount the volume

    The process for mounting a volume depends on the protocol your client is using. The following command mounts a volume called testvol using the native FUSE protocol.
    # mount -t glusterfs server1:testvol /mnt/glusterfs

20.2.2. Enabling I/O Encryption

Follow this section to enable I/O encryption between servers and clients.

Procedure 20.5. Enabling I/O encryption

Prerequisites

  • You must have volumes configured, but not started, to perform this process. See Chapter 5, Setting Up Storage Volumes for information on creating volumes. To stop a volume, run the following command:
    # gluster volume stop volname
Run the following commands from any Gluster server.
  1. Specify servers and clients to allow

    Provide a list of the common names of servers and clients that are allowed to access the volume. The common names provided must be exactly the same as the common name specified when you created the glusterfs.pem file for that server or client.
    # gluster volume set volname auth.ssl-allow 'server1,server2,client1,client2,client3'
    This provides an additional check in case you want to leave keys in place, but temporarily restrict a client or server by removing it from this list, as shown in Section 20.7, “Deauthorizing a Client”.
    You can also use the default value of *, which indicates that any TLS authenticated machine can mount and access the volume.
  2. Enable TLS/SSL on the volume

    # gluster volume set volname client.ssl on
    # gluster volume set volname server.ssl on
  3. Start the volume

    # gluster volume start volname
  4. Verify

    Verify that the volume can be mounted on authorized clients, and that the volume cannot be mounted by unauthorized clients. The process for mounting a volume depends on the protocol your client is using.
    The process for mounting a volume depends on the protocol your client is using. The following command mounts a volume called testvol using the native FUSE protocol.
    # mount -t glusterfs server1:testvol /mnt/glusterfs

20.3. Configuring Network Encryption for an existing Trusted Storage Pool

Follow this section to configure I/O and management encryption for an existing Red Hat Gluster Storage Trusted Storage Pool.

20.3.1. Enabling I/O Encryption

Follow this section to enable I/O encryption between servers and clients.

Procedure 20.6. Enabling I/O encryption

  1. Unmount the volume from all clients

    Unmount the volume by running the following command on all clients.
    # umount mountpoint
  2. Stop the volume

    Stop the volume by running the following command from any server.
    # gluster volume stop VOLNAME
  3. Specify servers and clients to allow

    Provide a list of the common names of servers and clients that are allowed to access the volume. The common names provided must be exactly the same as the common name specified when you created the glusterfs.pem file for that server or client.
    # gluster volume set volname auth.ssl-allow 'server1,server2,client1,client2,client3'
    This provides an additional check in case you want to leave keys in place, but temporarily restrict a client or server by removing it from this list, as shown in Section 20.7, “Deauthorizing a Client”.
    You can also use the default value of *, which indicates that any TLS authenticated machine can mount and access the volume.
  4. Enable TLS/SSL encryption on the volume

    Run the following command from any server to enable TLS/SSL encryption.
    # gluster volume set volname client.ssl on
    # gluster volume set volname server.ssl on
  5. Start the volume

    # gluster volume start volname
  6. Verify

    Verify that the volume can be mounted only on authorized clients. The process for mounting a volume depends on the protocol your client is using.
    The following command mounts a volume using the native FUSE protocol. Ensure that this command works on authorized clients, and does not work on unauthorized clients.
    # mount -t glusterfs server1:/testvolume /mnt/glusterfs

20.4. Enabling Management Encryption

Red Hat recommends enabling both management and I/O encryption, but if you only want to use I/O encryption, you can skip this section and continue with Section 20.3.1, “Enabling I/O Encryption”.

Prerequisites

  • Enabling management encryption requires that storage servers are offline. Schedule an outage window for volumes, applications, clients, and other end users before beginning this process. Be aware that features such as snapshots and geo-replication may also be affected by this outage.

Procedure 20.7. Enabling management encryption

  1. Prepare to enable encryption

    1. Unmount all volumes from all clients

      Run the following command on each client, for each volume mounted on that client.
      # umount mount-point
    2. Stop NFS Ganesha or SMB services, if used

      Run the following command on any gluster server to disable NFS-Ganesha.
      # systemctl stop nfs-ganesha
      Run the following command on any gluster server to stop SMB.
      # systemctl stop ctdb
    3. Unmount shared storage, if used

      Run the following command on all servers to unmount shared storage.
      # umount /var/run/gluster/shared_storage

      Note

      With the release of 3.5 Batch Update 3, the mount point of shared storage is changed from /var/run/gluster/ to /run/gluster/ .

      Important

      Features that require shared storage, such as snapshots and geo-replication, may not work until after this process is complete.
    4. Stop all volumes

      Run the following command on any server to stop all volumes, including the shared storage volume.
      # for vol in `gluster volume list`; do gluster --mode=script volume stop $vol; sleep 2s; done
    5. Stop gluster services on all servers

      For Red Hat Enterprise Linux 7 based installations:
      # systemctl stop glusterd
      # pkill glusterfs
      For Red Hat Enterprise Linux 6 based installations:
      # service glusterd stop
      # pkill glusterfs

      Important

      Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  2. Create and edit the secure-access file on all servers and clients

    Create a new /var/lib/glusterd/secure-access file. This file can be empty if you are using the default settings.
    # touch /var/lib/glusterd/secure-access
    Your Certificate Authority may require changes to the SSL certificate depth setting, transport.socket.ssl-cert-depth, in order to work correctly. To edit this setting, add the following line to the secure-access file, replacing n with the certificate depth required by your Certificate Authority.
    echo "option transport.socket.ssl-cert-depth n" > /var/lib/glusterd/secure-access
  3. Clean up after configuring management encryption

    1. Start the glusterd service on all servers

      For Red Hat Enterprise Linux 7 based installations:
      # systemctl start glusterd
      For Red Hat Enterprise Linux 6 based installations:
      # service glusterd start

      Important

      Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
    2. Start all volumes

      Run the following command on any host to start all volumes including shared storage.
      # for vol in `gluster volume list`; do gluster --mode=script volume start $vol; sleep 2s; done
    3. Mount shared storage, if used

      Run the following command on all servers to mount shared storage.
      # mount -t glusterfs hostname:/gluster_shared_storage /run/gluster/shared_storage
    4. Restart NFS Ganesha or SMB services, if used

      Run the following command on any gluster server to start NFS-Ganesha.
      # systemctl start nfs-ganesha
      Run the following command on any gluster server to start SMB.
      # systemctl start ctdb
    5. Mount volumes on clients

      The process for mounting a volume depends on the protocol your client is using. The following command mounts a volume using the native FUSE protocol.
      # mount -t glusterfs server1:/testvolume /mnt/glusterfs

20.5. Expanding Volumes

Follow this section to add new nodes to a trusted storage pool that uses network encryption.

20.5.1. Certificate signed by a Common Certificate Authority

Follow this section to add a new Gluster server to a trusted storage pool that uses network encryption signed by a common Certificate Authority.

Prerequisites

Procedure 20.8. Expanding a pool that uses common Certificate Authority signed certificates

  1. Import the common Certificate Authority list

    Copy the /etc/ssl/glusterfs.ca file from an existing server into the /etc/ssl directory of the new server.
  2. For management encryption, create and edit the secure-access file

    Create a new /var/lib/glusterd/secure-access file. This file can be empty if you are using the default settings.
    # touch /var/lib/glusterd/secure-access
    Your Certificate Authority may require changes to the SSL certificate depth setting, transport.socket.ssl-cert-depth, in order to work correctly. To edit this setting, add the following line to the secure-access file, replacing n with the certificate depth required by your Certificate Authority.
    echo "option transport.socket.ssl-cert-depth n" > /var/lib/glusterd/secure-access
  3. Start glusterd on the new server

    # systemctl start glusterd
  4. Specify servers and clients to allow

    Provide a list of the common names of servers and clients that are allowed to access the volume. The common names provided must be exactly the same as the common name specified when you created the glusterfs.pem file for that server or client.
    # gluster volume set volname auth.ssl-allow 'server1,server2,client1,client2,client3'
    This provides an additional check in case you want to leave keys in place, but temporarily restrict a client or server by removing it from this list, as shown in Section 20.7, “Deauthorizing a Client”.

    Note

    The gluster volume set command does not append to existing values of the options. To append the new name to the list, get the existing list using gluster volume info command, append the new name to the list and set the option again using gluster volume set command.
    You can also use the default value of *, which indicates that any TLS authenticated machine can mount and access the volume.
  5. Expand volumes to the new server

    Follow the instructions in Section 11.7, “Expanding Volumes” to expand existing volumes using the newly trusted server.

20.5.2. Self-signed Certificates

Prerequisites

  • Because self-signed certificates are not automatically generated and updated, the trusted storage pool must be offline for this process. Schedule an outage window for volumes, applications, clients, and other end users before beginning this process.

Procedure 20.9. Expanding a pool that uses self-signed certificates

  1. Generate the key and self-signed certificate for the new server

    Follow the steps in Section 20.1, “Preparing Certificates” to generate a private key and a self-signed certificate for the new server.
  2. Update server Certificate Authority list files

    Append the contents of the new server's /etc/ssl/glusterfs.pem file to the /etc/ssl/glusterfs.ca file on all existing servers in the trusted storage pool.
  3. Update client Certificate Authority list files

    Append the contents of the new server's /etc/ssl/glusterfs.pem file to the /etc/ssl/glusterfs.ca file on all authorized clients in the trusted storage pool.
  4. Stop all gluster processes

    Run the following commands on all servers.
    # systemctl stop glusterd
    # pkill glusterfs
  5. (Optional) Enable management encryption on the new server

    Copy the /var/lib/glusterd/secure-access file from an existing server to the new server.
  6. Start glusterd on the new server

    # systemctl start glusterd
  7. Update servers and clients to allow

    Run the following command from any server to specify the common names of servers and clients that are allowed to access the volume. The common names provided must be exactly the same as the common name specified when you created the glusterfs.pem file for that server or client.
    # gluster volume set volname auth.ssl-allow 'server1,server2,client1,client2,client3'

    Note

    The gluster volume set command does not append to existing values of the options. To append the new name to the list, get the existing list using gluster volume info command, append the new name to the list and set the option again using gluster volume set command.
    You can also use the default value of *, which indicates that any TLS authenticated machine can mount and access the volume.
  8. Restart the glusterfs processes on existing servers and clients

    1. On all clients, unmount all volumes

      # umount mountpoint
    2. On any server, stop all volumes

      # for vol in `gluster volume list`; do gluster --mode=script volume stop $vol; sleep 2s; done
    3. On all servers, restart glusterd

      For Red Hat Enterprise Linux 7 based installations:
      # systemctl start glusterd
      For Red Hat Enterprise Linux 6 based installations:
      # service glusterd start

      Important

      Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
    4. On any server, start all volumes

      # gluster volume start volname
  9. Mount the volume on all clients

    The process for mounting a volume depends on the protocol your client is using. The following command mounts a volume using the native FUSE protocol.
    # mount -t glusterfs server1:/test-volume /mnt/glusterfs
  10. Expand volumes to the new server

    Follow the instructions in Section 11.7, “Expanding Volumes” to expand existing volumes using the newly trusted server.

20.6. Authorizing a New Client

Follow this section to allow a new client to access a storage pool that uses network encryption.

20.6.1. Certificate Signed by a Common Certificate Authority

Follow this section to authorize a new client to access a trusted storage pool that uses network encryption signed by a common Certificate Authority.

Procedure 20.10. Authorizing a new client using a CA-signed certificate

  1. Generate a key for the client

    Run the following command on the client.
    # openssl genrsa -out /etc/ssl/glusterfs.key 2048
  2. Generate a certificate signing request

    The following command generates a certificate signing request for a certificate that expires in 365 days, instead of the default 30 days. Provide a short name for this machine in place of COMMONNAME. This is generally a hostname, FQDN, or IP address.
    # openssl req -new -sha256 -key /etc/ssl/glusterfs.key -subj '/CN=<COMMONNAME>' -days 365 -out glusterfs.csr
  3. Send the generated glusterfs.csr file to your Certificate Authority

    Your Certificate Authority provides a signed certificate for this machine in the form of a .pem file, and the Certificate Authority list in the form of a .ca file.
  4. Add provided certificate file on the client

    Place the .pem file provided by the Certificate Authority in the /etc/ssl directory on the client. Ensure that the .pem file is called glusterfs.pem.
  5. Add the Certificate Authority list to the client

    Copy the /etc/ssl/glusterfs.ca file from an existing client to your new client.
    # scp existingclient/etc/ssl/glusterfs.ca newclient:/etc/ssl/glusterfs.ca
  6. Verify your certificate

    Run the following command in the /etc/ssl directory to verify the certificate on that machine against the Certificate Authority list.
    # openssl verify -verbose -CAfile glusterfs.ca glusterfs.pem
    Your certificate is correct if the output of this command is glusterfs.pem: OK.
  7. Configure management encryption, if used

    On the client, create the /var/lib/glusterd directory, and create a new /var/lib/glusterd/secure-access file. This file can be empty if you are using the default settings.
    # touch /var/lib/glusterd/secure-access
    Your Certificate Authority may require changes to the SSL certificate depth setting, transport.socket.ssl-cert-depth, in order to work correctly. To edit this setting, add the following line to the secure-access file, replacing n with the certificate depth required by your Certificate Authority.
    echo "option transport.socket.ssl-cert-depth n" > /var/lib/glusterd/secure-access
  8. Update the list of servers and clients to allow

    Run the following command from any server to specify the common names of servers and clients that are allowed to access the volume. The common names provided must be exactly the same as the common name specified when you created the glusterfs.pem file for that server or client.
    # gluster volume set volname auth.ssl-allow 'server1,server2,client1,client2,client3'

    Note

    The gluster volume set command does not append to existing values of the options. To append the new name to the list, get the existing list using gluster volume info command, append the new name to the list and set the option again using gluster volume set command.
    You can also use the default value of *, which indicates that any TLS authenticated machine can mount and access the volume.
  9. Start the volume

    # gluster volume start volname
  10. Verify

    Verify that the volume can be mounted from the new client. The process for mounting a volume depends on the protocol your client is using.
    The following command mounts a volume using the native FUSE protocol. Ensure that this command works on authorized clients, and does not work on unauthorized clients.
    # mount -t glusterfs server1:testvolume /mnt/glusterfs

20.6.2. Self-signed Certificates

Prerequisites

  • Because self-signed certificates are not automatically generated and updated, the trusted storage pool must be offline for this process. Schedule an outage window for volumes, applications, clients, and other end users before beginning this process.
Follow this section to authorize a new client to access a trusted storage pool that uses network encryption with self-signed certificates.

Procedure 20.11. Authorizing a new client using a self-signed certificate

  1. Generate a key for the client

    Run the following command on the client.
    # openssl genrsa -out /etc/ssl/glusterfs.key 2048
  2. Generate a self-signed certificate for the client

    The following command generates a signed certificate that expires in 365 days, instead of the default 30 days. Provide a short name for this machine in place of COMMONNAME. This is generally a hostname, FQDN, or IP address.
    # openssl req -new -x509 -key /etc/ssl/glusterfs.key -subj "/CN=COMMONNAME" -days 365 -out /etc/ssl/glusterfs.pem
  3. Add the Certificate Authority list to the client

    Copy the /etc/ssl/glusterfs.ca file from an existing client to your new client. Run the following command from the new client.
    # scp existingclient:/etc/ssl/glusterfs.ca /etc/ssl/glusterfs.ca
  4. Generate new server glusterfs.ca files

    On any server, append the value of the new client's /etc/ssl/glusterfs.pem file to the end of the server's /etc/ssl/glusterfs.ca file.
    Place the updated /etc/ssl/glusterfs.ca file in the /etc/ssl directory of all servers in the trusted storage pool.
    For example, running the following commands on any server updates the glusterfs.ca file with the .pem file from the new client, and then copies that glusterfs.ca file to all servers.
    # ssh user@newclient cat /etc/ssl/glusterfs.pem >> /etc/ssl/glusterfs.ca
    # scp /etc/ssl/glusterfs.ca server1:/etc/ssl/glusterfs.ca
    # scp /etc/ssl/glusterfs.ca server2:/etc/ssl/glusterfs.ca
  5. Configure management encryption on the new client, if used

    On the client, create the /var/lib/glusterd directory, and create a new /var/lib/glusterd/secure-access file. This file can be empty if you are using the default settings.
    # touch /var/lib/glusterd/secure-access
    Your Certificate Authority may require changes to the SSL certificate depth setting, transport.socket.ssl-cert-depth, in order to work correctly. To edit this setting, add the following line to the secure-access file, replacing n with the certificate depth required by your Certificate Authority.
    echo "option transport.socket.ssl-cert-depth n" > /var/lib/glusterd/secure-access
  6. Update the list of servers and clients to allow

    Run the following command from any server to specify the common names of servers and clients that are allowed to access the volume. The common names provided must be exactly the same as the common name specified when you created the glusterfs.pem file for that server or client.
    # gluster volume set volname auth.ssl-allow 'server1,server2,client1,client2,client3'

    Note

    The gluster volume set command does not append to existing values of the options. To append the new name to the list, get the existing list using gluster volume info command, append the new name to the list and set the option again using gluster volume set command.
    You can also use the default value of *, which indicates that any TLS authenticated machine can mount and access the volume.
  7. Start the volume

    Run the following command from any server to start the volume.
    # gluster volume start volname
  8. If management encryption is used, restart glusterd on all servers

    For Red Hat Enterprise Linux 7 based installations:
    # systemctl start glusterd
    For Red Hat Enterprise Linux 6 based installations:
    # service glusterd start

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  9. Verify

    Verify that the volume can be mounted from the new client. The process for mounting a volume depends on the protocol your client is using.
    The following command mounts a volume using the native FUSE protocol. Ensure that this command works on authorized clients, and does not work on unauthorized clients.
    # mount -t glusterfs server1:testvolume /mnt/glusterfs

20.7. Deauthorizing a Client

To revoke the authorization of a client to access the Red Hat Gluster Storage trusted storage pool, you can do any of the following:
  • Remove an authorized client from the allowed list
  • Revoke SSL/TLS certificate authorization through a certificate revocation list (CRL)

20.7.1. To Remove an Authorized Client From the Allowed List

Procedure 20.12. Removing an authorized client from the allowed list

  1. List currently authorized clients and servers

    $ gluster volume get VOLNAME auth.ssl-allow
    For example, the following command shows that there are three authorized servers and five authorized clients.
    $ gluster volume get sample_volname auth.ssl-allow
    server1,server2,server3,client1,client2,client3,client4,client5
  2. Remove clients to deauthorize from the output

    For example, if you want to deauthorize client2 and client4, copy the string and remove those clients from the list.
    server1,server2,server3,client1,client3,client5
  3. Set the new list of authorized clients and servers

    Set the value of auth.ssl-allow to your updated string.
    $ gluster volume set VOLNAME auth.ssl-allow <list_of_systems>
    For example, the updated list shows three servers and three clients.
    $ gluster volume set sample_volname auth.ssl-allow server1,server2,server3,client1,client3,client5

20.7.2. To Revoke SSL/TLS Certificate Authorization Using a SSL Certificate Revocation List

To protect the cluster from malicious or unauthorized network entities, you can specify a path to a directory containing SSL certificate revocation list (CRL) using the ssl.crl-path option. The path containing the list of revoked certificates enables server nodes to stop the nodes with revoked certificates from accessing the cluster.
For example, you can provide the path to a directory containing CRL with the volume set command as follows:
$ gluster volume set vm-images ssl.crl-path /etc/ssl/

Note

Only the CA signed certificates can be revoked and not the self-signed certificates
To set up the CRL files, perform the following:
  1. Copy the CRL files to a directory.
  2. Change directory to the directory containing CRL files.
  3. Compute hashes to the CRL files using the c_rehash utility.
    $ c_rehash .
    The hash and symbolic linking can be done using the c_rehash utility, which is available through the openssl-perl RPM. The name of the symbolic link must be the hash of the Common Name. For more information, see the crl man page.
  4. Set the ssl.crl-path volume option.
    $ gluster volume set VOLNAME ssl.crl-path path-to-directory
    where, path-to-directory has to be an absolute name of the directory that hosts the CRL files.

20.8. Disabling Network Encryption

Follow this section to disable network encryption on clients and servers.

Procedure 20.13. Disabling I/O encryption

  1. Unmount volumes from all clients

    Run the following command on each client for any volume that should have encryption disabled.
    # umount /mountpoint
  2. Stop encrypted volumes

    Run the following command on any server to stop volumes that should have encryption disabled.
    # gluster volume stop volname
  3. Disable server and client SSL usage

    Run the following commands for each volume that should have encryption disabled.
    # gluster volume set volname server.ssl off
    # gluster volume set volname client.ssl off
  4. Start volumes

    # gluster volume start volname
  5. Mount volumes on clients

    The process for mounting a volume depends on the protocol your client is using. The following command mounts a volume using the native FUSE protocol.
    # mount -t glusterfs server1:/testvolume /mnt/glusterfs

Procedure 20.14. Disabling management encryption

  1. Unmount volumes from all clients

    Run the following command on each client for any volume that should have encryption disabled.
    # umount /mountpoint
  2. Stop glusterd on all nodes

    For Red Hat Enterprise Linux 7 based installations:
    # systemctl stop glusterd
    For Red Hat Enterprise Linux 6 based installations:
    # service glusterd stop

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  3. Remove the secure-access file

    Run the following command on all servers and clients to remove the secure-access file. You can just rename the file if you are only disabling encryption temporarily.
    # rm -f /var/lib/glusterd/secure-access
  4. Start glusterd on all nodes

    For Red Hat Enterprise Linux 7 based installations:
    # systemctl start glusterd
    For Red Hat Enterprise Linux 6 based installations:
    # service glusterd start

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  5. Mount volumes on clients

    The process for mounting a volume depends on the protocol your client is using. The following command mounts a volume using the native FUSE protocol.
    # mount -t glusterfs server1:/testvolume /mnt/glusterfs

Important

If you are permanently disabling network encryption, you can now delete the SSL certificate files. Do not delete these files if you are only disabling encryption temporarily.

Part VII. Troubleshoot

Chapter 21. Resolving Common Issues

This chapter provides some of the Red Hat Gluster Storage troubleshooting methods.

21.1. Identifying locked file and clear locks

You can use the statedump command to list the locks held on files. The statedump output also provides information on each lock with its range, basename, and PID of the application holding the lock, and so on. You can analyze the output to find the locks whose owner/application is no longer running or interested in that lock. After ensuring that no application is using the file, you can clear the lock using the following clear-locks command:
# gluster volume clear-locks VOLNAME path kind {blocked | granted | all}{inode range | entry basename | posix range}
For more information on performing statedump, see Section 17.7, “Viewing complete volume state with statedump”
To identify locked file and clear locks
  1. Perform statedump on the volume to view the files that are locked using the following command:
    # gluster volume statedump VOLNAME
    For example, to display statedump of test-volume:
    # gluster volume statedump test-volume
    Volume statedump successful
    The statedump files are created on the brick servers in the /tmp directory or in the directory set using the server.statedump-path volume option. The naming convention of the dump file is brick-path.brick-pid.dump.
  2. Clear the entry lock using the following command:
    # gluster volume clear-locks VOLNAME path kind granted entry basename
    The following are the sample contents of the statedump file indicating entry lock (entrylk). Ensure that those are stale locks and no resources own them.
    [xlator.features.locks.vol-locks.inode]
    path=/
    mandatory=0
    entrylk-count=1
    lock-dump.domain.domain=vol-replicate-0
    xlator.feature.locks.lock-dump.domain.entrylk.entrylk[0](ACTIVE)=type=ENTRYLK_WRLCK on basename=file1, pid = 714782904, owner=ffffff2a3c7f0000, transport=0x20e0670, , granted at Mon Feb 27 16:01:01 2012
    
    conn.2.bound_xl./rhgs/brick1.hashsize=14057
    conn.2.bound_xl./rhgs/brick1.name=/gfs/brick1/inode
    conn.2.bound_xl./rhgs/brick1.lru_limit=16384
    conn.2.bound_xl./rhgs/brick1.active_size=2
    conn.2.bound_xl./rhgs/brick1.lru_size=0
    conn.2.bound_xl./rhgs/brick1.purge_size=0
    For example, to clear the entry lock on file1 of test-volume:
    # gluster volume clear-locks test-volume / kind granted entry file1
    Volume clear-locks successful
    test-volume-locks: entry blocked locks=0 granted locks=1
  3. Clear the inode lock using the following command:
    # gluster volume clear-locks VOLNAME path kind granted inode range
    The following are the sample contents of the statedump file indicating there is an inode lock (inodelk). Ensure that those are stale locks and no resources own them.
    [conn.2.bound_xl./rhgs/brick1.active.1]
    gfid=538a3d4a-01b0-4d03-9dc9-843cd8704d07
    nlookup=1
    ref=2
    ia_type=1
    [xlator.features.locks.vol-locks.inode]
    path=/file1
    mandatory=0
    inodelk-count=1
    lock-dump.domain.domain=vol-replicate-0
    inodelk.inodelk[0](ACTIVE)=type=WRITE, whence=0, start=0, len=0, pid = 714787072, owner=00ffff2a3c7f0000, transport=0x20e0670, , granted at Mon Feb 27 16:01:01 2012
    For example, to clear the inode lock on file1 of test-volume:
    # gluster  volume clear-locks test-volume /file1 kind granted inode 0,0-0
    Volume clear-locks successful
    test-volume-locks: inode blocked locks=0 granted locks=1
  4. Clear the granted POSIX lock using the following command:
    # gluster volume clear-locks VOLNAME path kind granted posix range
    The following are the sample contents of the statedump file indicating there is a granted POSIX lock. Ensure that those are stale locks and no resources own them.
    xlator.features.locks.vol1-locks.inode]
    path=/file1
    mandatory=0
    posixlk-count=15
    posixlk.posixlk[0](ACTIVE)=type=WRITE, whence=0, start=8, len=1, pid = 23848, owner=d824f04c60c3c73c, transport=0x120b370, , blocked at Mon Feb 27 16:01:01 2012
    , granted at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[1](ACTIVE)=type=WRITE, whence=0, start=7, len=1, pid = 1, owner=30404152462d436c-69656e7431, transport=0x11eb4f0, , granted at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[2](BLOCKED)=type=WRITE, whence=0, start=8, len=1, pid = 1, owner=30404152462d436c-69656e7431, transport=0x11eb4f0, , blocked at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[3](ACTIVE)=type=WRITE, whence=0, start=6, len=1, pid = 12776, owner=a36bb0aea0258969, transport=0x120a4e0, , granted at Mon Feb 27 16:01:01 2012
    ...
    For example, to clear the granted POSIX lock on file1 of test-volume:
    # gluster volume clear-locks test-volume /file1 kind granted posix 0,8-1
    Volume clear-locks successful
    test-volume-locks: posix blocked locks=0 granted locks=1
    test-volume-locks: posix blocked locks=0 granted locks=1
    test-volume-locks: posix blocked locks=0 granted locks=1
  5. Clear the blocked POSIX lock using the following command:
    # gluster volume clear-locks VOLNAME path kind blocked posix range
    The following are the sample contents of the statedump file indicating there is a blocked POSIX lock. Ensure that those are stale locks and no resources own them.
    [xlator.features.locks.vol1-locks.inode]
    path=/file1
    mandatory=0
    posixlk-count=30
    posixlk.posixlk[0](ACTIVE)=type=WRITE, whence=0, start=0, len=1, pid = 23848, owner=d824f04c60c3c73c, transport=0x120b370, , blocked at Mon Feb 27 16:01:01 2012
    , granted at Mon Feb 27 16:01:01
    
    posixlk.posixlk[1](BLOCKED)=type=WRITE, whence=0, start=0, len=1, pid = 1, owner=30404146522d436c-69656e7432, transport=0x1206980, , blocked at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[2](BLOCKED)=type=WRITE, whence=0, start=0, len=1, pid = 1, owner=30404146522d436c-69656e7432, transport=0x1206980, , blocked at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[3](BLOCKED)=type=WRITE, whence=0, start=0, len=1, pid = 1, owner=30404146522d436c-69656e7432, transport=0x1206980, , blocked at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[4](BLOCKED)=type=WRITE, whence=0, start=0, len=1, pid = 1, owner=30404146522d436c-69656e7432, transport=0x1206980, , blocked at Mon Feb 27 16:01:01 2012
    
    ...
    For example, to clear the blocked POSIX lock on file1 of test-volume:
    # gluster volume clear-locks test-volume /file1 kind blocked posix 0,0-1
    Volume clear-locks successful
    test-volume-locks: posix blocked locks=28 granted locks=0
    test-volume-locks: posix blocked locks=1 granted locks=0
    No locks cleared.
  6. Clear all POSIX locks using the following command:
    # gluster volume clear-locks VOLNAME path kind all posix range
    The following are the sample contents of the statedump file indicating that there are POSIX locks. Ensure that those are stale locks and no resources own them.
    [xlator.features.locks.vol1-locks.inode]
    path=/file1
    mandatory=0
    posixlk-count=11
    posixlk.posixlk[0](ACTIVE)=type=WRITE, whence=0, start=8, len=1, pid = 12776, owner=a36bb0aea0258969, transport=0x120a4e0, , blocked at Mon Feb 27 16:01:01 2012
    , granted at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[1](ACTIVE)=type=WRITE, whence=0, start=0, len=1, pid = 12776, owner=a36bb0aea0258969, transport=0x120a4e0, , granted at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[2](ACTIVE)=type=WRITE, whence=0, start=7, len=1, pid = 23848, owner=d824f04c60c3c73c, transport=0x120b370, , granted at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[3](ACTIVE)=type=WRITE, whence=0, start=6, len=1, pid = 1, owner=30404152462d436c-69656e7431, transport=0x11eb4f0, , granted at Mon Feb 27 16:01:01 2012
    
    posixlk.posixlk[4](BLOCKED)=type=WRITE, whence=0, start=8, len=1, pid = 23848, owner=d824f04c60c3c73c, transport=0x120b370, , blocked at Mon Feb 27 16:01:01 2012
    ...
    For example, to clear all POSIX locks on file1 of test-volume:
    # gluster volume clear-locks test-volume /file1 kind all posix 0,0-1
    Volume clear-locks successful
    test-volume-locks: posix blocked locks=1 granted locks=0
    No locks cleared.
    test-volume-locks: posix blocked locks=4 granted locks=1
You can perform statedump on test-volume again to verify that all the above locks are cleared.

21.2. Retrieving File Path from the Gluster Volume

The heal info command lists the GFIDs of the files that needs to be healed. If you want to find the path of the files associated with the GFIDs, use the getfattr utility. The getfattr utility enables you to locate a file residing on a gluster volume brick. You can retrieve the path of a file even if the filename is unknown.

21.2.1. Retrieving Known File Name

To retrieve a file path when the file name is known, execute the following command in the Fuse mount directory:
# getfattr -n trusted.glusterfs.pathinfo -e text <path_to_fuse_mount/filename>
Where,
path_to_fuse_mount: The fuse mount where the gluster volume is mounted.
filename: The name of the file for which the path information is to be retrieved.
For example:
# getfattr  -n trusted.glusterfs.pathinfo -e text /mnt/fuse_mnt/File1
getfattr: Removing leading '/' from absolute path names
# file: mnt/fuse_mnt/File1
trusted.glusterfs.pathinfo="(<DISTRIBUTE:testvol-dht> (<REPLICATE:testvol-replicate-0>
<POSIX(/rhgs/brick1):tuxpad:/rhgs/brick1/File1>
<POSIX(/rhgs/brick2):tuxpad:/rhgs/brick2/File1>))"
The command output displays the brick pathinfo under the <POSIX> tag. In this example output, two paths are displayed as the file is replicated twice.

21.2.2. Retrieving Unknown File Name

You can retrieve the file path of an unknown file using its gfid string. The gfid string is the hyphenated version of the trusted.gfid attribute. For example, if the gfid is 80b0b1642ea4478ba4cda9f76c1e6efd, then the gfid string will be 80b0b164-2ea4-478b-a4cd-a9f76c1e6efd.

Note

To obtain the gfid of a file, run the following command:
# getfattr -d -m. -e hex /path/to/file/on/the/brick

21.2.3. Retrieving File Path using gfid String

To retrieve the file path using the gfid string, follow these steps:
  1. Fuse mount the volume with the aux-gfid option enabled.
    # mount -t glusterfs -o aux-gfid-mount hostname:volume-name  <path_to_fuse_mnt>
    Where,
    path_to_fuse_mount: The fuse mount where the gluster volume is mounted.
    For example:
    # mount -t glusterfs -o aux-gfid-mount 127.0.0.2:testvol /mnt/aux_mount
  2. After mounting the volume, execute the following command
    # getfattr -n trusted.glusterfs.pathinfo -e text <path-to-fuse-mnt>/.gfid/<GFID string>
    Where,
    path_to_fuse_mount: The fuse mount where the gluster volume is mounted.
    GFID string: The GFID string.
    For example:
    # getfattr -n trusted.glusterfs.pathinfo -e text /mnt/aux_mount/.gfid/80b0b164-2ea4-478b-a4cd-a9f76c1e6efd
    getfattr: Removing leading '/' from absolute path names
    # file: mnt/aux_mount/.gfid/80b0b164-2ea4-478b-a4cd-a9f76c1e6efd trusted.glusterfs.pathinfo="(<DISTRIBUTE:testvol-dht> (<REPLICATE:testvol-replicate-0> <POSIX(/rhgs/brick2):tuxpad:/rhgs/brick2/File1> <POSIX(/rhgs/brick1):tuxpad:/rhgs/brick1/File1>))
    The command output displays the brick pathinfo under the <POSIX> tag. In this example output, two paths are displayed as the file is replicated twice.

21.2.4. Controlling Self-heal for Dispersed Volumes

For dispersed volumes, when a node with multiple bricks goes offline and comes back online, self-heal daemon starts healing the bricks. This self-heal can lead to high CPU usage in case of large amounts of data and can affect the ongoing I/O operations, thus, decreasing storage efficiency.
To control the CPU and memory usage of the self-heal daemon, follow these steps:
  1. Navigate to the scripts folder using the following command:
    # cd /usr/share/glusterfs/scripts
  2. Determine the PID of the self-heal daemon using the following command:
    # ps -aef | grep glustershd
    The output will be in the following format:
    root      1565     1  0 Feb05 ?        00:09:17 /usr/sbin/glusterfs -s localhost --volfile-id gluster/glustershd -p /var/run/gluster/glustershd/glustershd.pid -l /var/log/glusterfs/glustershd.log -S /var/run/gluster/ed49b959a0dc9b2185913084e3b2b339.socket --xlator-option *replicate*.node-uuid=13dbfa1e-ebbf-4cee-a1ac-ca6763903c55
    root     16766 14420  0 19:00 pts/0    00:00:00 grep --color=auto glustershd
    In this output, 1565 represents the PID of the selfheald service.
  3. Execute the control-cpu-load script using the following command:
    # sh control-cpu-load.sh
  4. When the system prompts for the following input, type the PID of the self-heal daemon acquired from the previous step and press Enter:
    [root@XX-XX scripts]# sh control-cpu-load.sh
    Enter gluster daemon pid for which you want to control CPU.
    1565
  5. When the system prompts for the following input, type y and press Enter:
    If you want to continue the script to attach 1565 with new cgroup_gluster_1565 cgroup Press (y/n)?
    In this example, 1565 represents the PID of the selfheald service. The PID of the selfheald service can vary from system to system.
  6. When the system prompts for the following input, enter the required quota value to be assigned to the self-heal daemon and press Enter:
    Creating child cgroup directory 'cgroup_gluster_1565 cgroup' for glustershd.service.
    Enter quota value in range [10,100]:
    25
    
    In this example, the quota value for the self-heal daemon is set as 25.

    Note

    The recommended quota value for a self-heal daemon is 25. However, the quota value can be set by the user on a run-time basis.
    The system prompts the following notification once the quota value is successfully set:
    Entered quota value is 25
    Setting 25000 to cpu.cfs_quota_us for gluster_cgroup.
    Tasks are attached successfully specific to 1565 to cgroup_gluster_1565.
To check the CPU usage for the self-heal daemon, execute the top command.

Important

Perform this procedure every time the daemon is restarted with the new daemon PID.

21.3. Resolving glusterd Crash

glusterd crash is observed in the following scenarios:
  • glusterd recieves a Termination Signal or SIGTERM.
  • Segmentation fault error message when upgrading Red Hat Gluster Storage.
  • glusterd service is being stopped.

Important

There is no functionality impact to these crashes as they occur during the shutdown path of glusterd.
If the glusterd crash is persistent in any other scenarios, contact Red Hat Support

21.4. Restarting a dead/failed brick

Note

In case of a Red Hat OpenShift Container Storage converged and independent mode, where brick multiplexing is enabled by default, the volumes for which the failed/dead bricks are multiplexed into a single process need to be force started.
If any bricks associated with a volume are down, start the bricks by executing the following command:
# gluster volume start VOLNAME force

21.5. Deactivating a group configuration

Use this procedure to deactivate group configurations like metadata-cache, nl-cache, or samba. Use this procedure to reset volume options set up by a group configuration in order to deactivate the group.
  1. Navigate to the groups folder:
    # cd /var/lib/glusterd/groups
  2. View the contents of the group profile:
    # cat PROFILE_NAME
  3. Reset each volume option present in the group profile:
    # gluster volume reset VOLNAME OPTION_NAME

Part VIII. Appendices

Chapter 22. Starting and Stopping the glusterd service

Using the glusterd command line, logical storage volumes can be decoupled from physical hardware. Decoupling allows storage volumes to be grown, resized, and shrunk, without application or server downtime.
Regardless of changes made to the underlying hardware, the trusted storage pool is always available while changes to the underlying hardware are made. As storage is added to the trusted storage pool, volumes are rebalanced across the pool to accommodate the added storage capacity.
The glusterd service is started automatically on all servers in the trusted storage pool. The service can also be manually started and stopped as required.
  • Run the following command to start glusterd manually.
    On RHEL 7 and RHEL 8, run
    # systemctl start glusterd
    On RHEL 6, run
    # service glusterd start

    Important

    Red Hat Gluster Storage is not supported on Red Hat Enterprise Linux 6 (RHEL 6) from 3.5 Batch Update 1 onwards. See Version Details table in section Red Hat Gluster Storage Software Components and Versions of the Installation Guide
  • Run the following command to stop glusterd manually.
    On RHEL 7 and RHEL 8, run
    # systemctl stop glusterd
    On RHEL 6, run
    # service glusterd stop
When a Red Hat Gluster Storage server node that hosts a very large number of bricks or snapshots is upgraded, cluster management commands may become unresponsive as glusterd attempts to start all brick processes concurrently for all bricks and snapshots. If you have more than 250 bricks or snapshots being hosted by a single node, Red Hat recommends deactivating snapshots until upgrade is complete.

Chapter 23. Manually Recovering File Split-brain

This chapter provides steps to manually recover from split-brain.
  1. Run the following command to obtain the path of the file that is in split-brain:
    # gluster volume heal VOLNAME info split-brain
    From the command output, identify the files for which file operations performed from the client keep failing with Input/Output error.
  2. Close the applications that opened split-brain file from the mount point. If you are using a virtual machine, you must power off the machine.
  3. Obtain and verify the AFR changelog extended attributes of the file using the getfattr command. Then identify the type of split-brain to determine which of the bricks contains the 'good copy' of the file.
    getfattr -d -m . -e hex <file-path-on-brick>
    For example,
    # getfattr -d -e hex -m. brick-a/file.txt
    #file: brick-a/file.txt
    security.selinux=0x726f6f743a6f626a6563745f723a66696c655f743a733000
    trusted.afr.vol-client-2=0x000000000000000000000000
    trusted.afr.vol-client-3=0x000000000200000000000000
    trusted.gfid=0x307a5c9efddd4e7c96e94fd4bcdcbd1b
    The extended attributes with trusted.afr.VOLNAMEvolname-client-<subvolume-index> are used by AFR to maintain changelog of the file. The values of the trusted.afr.VOLNAMEvolname-client-<subvolume-index> are calculated by the glusterFS client (FUSE or NFS-server) processes. When the glusterFS client modifies a file or directory, the client contacts each brick and updates the changelog extended attribute according to the response of the brick.
    subvolume-index is the brick number - 1 of gluster volume info VOLNAME output.
    For example,
    # gluster volume info vol
    Volume Name: vol
    Type: Distributed-Replicate
    Volume ID: 4f2d7849-fbd6-40a2-b346-d13420978a01
    Status: Created
    Number of Bricks: 4 x 2 = 8
    Transport-type: tcp
    Bricks:
    brick1: server1:/rhgs/brick1
    brick2: server1:/rhgs/brick2
    brick3: server1:/rhgs/brick3
    brick4: server1:/rhgs/brick4
    brick5: server1:/rhgs/brick5
    brick6: server1:/rhgs/brick6
    brick7: server1:/rhgs/brick7
    brick8: server1:/rhgs/brick8
    In the example above:
    Brick             |    Replica set        |    Brick subvolume index
    ----------------------------------------------------------------------------
    /rhgs/brick1     |       0               |       0
    /rhgs/brick2     |       0               |       1
    /rhgs/brick3     |       1               |       2
    /rhgs/brick4     |       1               |       3
    /rhgs/brick5     |       2               |       4
    /rhgs/brick6     |       2               |       5
    /rhgs/brick7     |       3               |       6
    /rhgs/brick8     |       3               |       7
    ```
    Each file in a brick maintains the changelog of itself and that of the files present in all the other bricks in it's replica set as seen by that brick.
    In the example volume given above, all files in brick-a will have 2 entries, one for itself and the other for the file present in it's replica pair. The following is the changelog for brick2,
    • trusted.afr.vol-client-0=0x000000000000000000000000 - is the changelog for itself (brick1)
    • trusted.afr.vol-client-1=0x000000000000000000000000 - changelog for brick2 as seen by brick1
    Likewise, all files in brick2 will have the following:
    • trusted.afr.vol-client-0=0x000000000000000000000000 - changelog for brick1 as seen by brick2
    • trusted.afr.vol-client-1=0x000000000000000000000000 - changelog for itself (brick2)

    Note

    These files do not have entries for themselves, only for the other bricks in the replica. For example, brick1 will only have trusted.afr.vol-client-1 set and brick2 will only have trusted.afr.vol-client-0 set. Interpreting the changelog remains same as explained below.
    The same can be extended for other replica pairs.
    Interpreting changelog (approximate pending operation count) value

    Each extended attribute has a value which is 24 hexa decimal digits. First 8 digits represent changelog of data. Second 8 digits represent changelog of metadata. Last 8 digits represent Changelog of directory entries.

    Pictorially representing the same is as follows:
    0x 000003d7 00000001 00000000110
            |      |       |
            |      |        \_ changelog of directory entries
            |       \_ changelog of metadata
             \ _ changelog of data
    For directories, metadata and entry changelogs are valid. For regular files, data and metadata changelogs are valid. For special files like device files and so on, metadata changelog is valid. When a file split-brain happens it could be either be data split-brain or meta-data split-brain or both.
    The following is an example of both data, metadata split-brain on the same file:
    # getfattr -d -m . -e hex /rhgs/brick?/a
    getfattr: Removing leading '/' from absolute path names
    #file: rhgs/brick1/a
    trusted.afr.vol-client-0=0x000000000000000000000000
    trusted.afr.vol-client-1=0x000003d70000000100000000
    trusted.gfid=0x80acdbd886524f6fbefa21fc356fed57
    #file: rhgs/brick2/a
    trusted.afr.vol-client-0=0x000003b00000000100000000
    trusted.afr.vol-client-1=0x000000000000000000000000
    trusted.gfid=0x80acdbd886524f6fbefa21fc356fed57
    Scrutinize the changelogs

    The changelog extended attributes on file /rhgs/brick1/a are as follows:
    • The first 8 digits of trusted.afr.vol-client-0 are all zeros (0x00000000................),
      The first 8 digits of trusted.afr.vol-client-1 are not all zeros (0x000003d7................).
      So the changelog on /rhgs/brick-a/a implies that some data operations succeeded on itself but failed on /rhgs/brick2/a.
    • The second 8 digits of trusted.afr.vol-client-0 are all zeros (0x........00000000........), and the second 8 digits of trusted.afr.vol-client-1 are not all zeros (0x........00000001........).
      So the changelog on /rhgs/brick1/a implies that some metadata operations succeeded on itself but failed on /rhgs/brick2/a.
    The changelog extended attributes on file /rhgs/brick2/a are as follows:
    • The first 8 digits of trusted.afr.vol-client-0 are not all zeros (0x000003b0................).
      The first 8 digits of trusted.afr.vol-client-1 are all zeros (0x00000000................).
      So the changelog on /rhgs/brick2/a implies that some data operations succeeded on itself but failed on /rhgs/brick1/a.
    • The second 8 digits of trusted.afr.vol-client-0 are not all zeros (0x........00000001........)
      The second 8 digits of trusted.afr.vol-client-1 are all zeros (0x........00000000........).
      So the changelog on /rhgs/brick2/a implies that some metadata operations succeeded on itself but failed on /rhgs/brick1/a.
    Here, both the copies have data, metadata changes that are not on the other file. Hence, it is both data and metadata split-brain.
    Deciding on the correct copy

    You must inspect stat and getfattr output of the files to decide which metadata to retain and contents of the file to decide which data to retain. To continue with the example above, here, we are retaining the data of /rhgs/brick1/a and metadata of /rhgs/brick2/a.

    Resetting the relevant changelogs to resolve the split-brain

    Resolving data split-brain

    You must change the changelog extended attributes on the files as if some data operations succeeded on /rhgs/brick1/a but failed on /rhgs/brick-b/a. But /rhgs/brick2/a should not have any changelog showing data operations succeeded on /rhgs/brick2/a but failed on /rhgs/brick1/a. You must reset the data part of the changelog on trusted.afr.vol-client-0 of /rhgs/brick2/a.

    Resolving metadata split-brain

    You must change the changelog extended attributes on the files as if some metadata operations succeeded on /rhgs/brick2/a but failed on /rhgs/brick1/a. But /rhgs/brick1/a should not have any changelog which says some metadata operations succeeded on /rhgs/brick1/a but failed on /rhgs/brick2/a. You must reset metadata part of the changelog on trusted.afr.vol-client-1 of /rhgs/brick1/a
    Run the following commands to reset the extended attributes.
    1. On /rhgs/brick2/a, for trusted.afr.vol-client-0 0x000003b00000000100000000 to 0x000000000000000100000000, execute the following command:
      # setfattr -n trusted.afr.vol-client-0 -v 0x000000000000000100000000 /rhgs/brick2/a
    2. On /rhgs/brick1/a, for trusted.afr.vol-client-1 0x0000000000000000ffffffff to 0x000003d70000000000000000, execute the following command:
      # setfattr -n trusted.afr.vol-client-1 -v 0x000003d70000000000000000 /rhgs/brick1/a
    After you reset the extended attributes, the changelogs would look similar to the following:
    # getfattr -d -m . -e hex /rhgs/brick?/a
    getfattr: Removing leading '/' from absolute path names
    #file: rhgs/brick1/a
    trusted.afr.vol-client-0=0x000000000000000000000000
    trusted.afr.vol-client-1=0x000003d70000000000000000
    trusted.gfid=0x80acdbd886524f6fbefa21fc356fed57
    
    #file: rhgs/brick2/a
    trusted.afr.vol-client-0=0x000000000000000100000000
    trusted.afr.vol-client-1=0x000000000000000000000000
    trusted.gfid=0x80acdbd886524f6fbefa21fc356fed57
    
    Resolving Directory entry split-brain

    AFR has the ability to conservatively merge different entries in the directories when there is a split-brain on directory. If on one brick directory storage has entries 1, 2 and has entries 3, 4 on the other brick then AFR will merge all of the entries in the directory to have 1, 2, 3, 4 entries in the same directory. But this may result in deleted files to re-appear in case the split-brain happens because of deletion of files on the directory. Split-brain resolution needs human intervention when there is at least one entry which has same file name but different gfid in that directory.

    For example:
    On brick-a the directory has 2 entries file1 with gfid_x and file2 . On brick-b directory has 2 entries file1 with gfid_y and file3. Here the gfid's of file1 on the bricks are different. These kinds of directory split-brain needs human intervention to resolve the issue. You must remove either file1 on brick-a or the file1 on brick-b to resolve the split-brain.
    In addition, the corresponding gfid-link file must be removed. The gfid-link files are present in the .glusterfs directory in the top-level directory of the brick. If the gfid of the file is 0x307a5c9efddd4e7c96e94fd4bcdcbd1b (the trusted.gfid extended attribute received from the getfattr command earlier), the gfid-link file can be found at /rhgs/brick1/.glusterfs/30/7a/307a5c9efddd4e7c96e94fd4bcdcbd1b.

    Warning

    Before deleting the gfid-link, you must ensure that there are no hard links to the file present on that brick. If hard-links exist, you must delete them.
  4. Trigger self-heal by running the following command:
    # ls -l <file-path-on-gluster-mount>
    or
    # gluster volume heal VOLNAME

Appendix A. Revision History

Revision History
Revision 3.5-0Wed Oct 30 2019Red Hat Gluster Storage Documentation Team
Updated documentation for Red Hat Gluster Storage 3.5

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