7.2. NFS

Linux, and other operating systems that support the NFSv3 standard can use NFS to access the Red Hat Gluster Storage volumes.
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

7.2.1. Using NFS to Mount Red Hat Gluster Storage Volumes

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 7.2.1.4, “Testing Volumes Mounted Using NFS”.

7.2.1.1. Manually Mounting Volumes Using NFS

Create a mount point and run the mount command to manually mount a Red Hat Gluster Storage volume using 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 NFS over TCP
Create a mount point and run the mount command to manually mount a Red Hat Gluster Storage volume using 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

7.2.1.2. Automatically Mounting Volumes Using NFS

Red Hat Gluster Storage volumes can be mounted automatically using 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 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 glusterfs 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 glusterfs 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

7.2.1.3. Authentication Support for Subdirectory Mount

This update extends nfs.export-dir option to provide client authentication during sub-directory mount. 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 with either an IP, host name or a Classless Inter-Domain Routing (CIDR) range.
  • nfs.export-dirs: By default, all NFS sub-volumes are exported as individual exports. This option allows you to manage this behavior. When this option is turned off, none of the sub-volumes are exported and hence the sub-directories cannot be mounted. This option is on by default.
    To set this option to off, run the following command:
    # gluster volume set VOLNAME nfs.export-dirs off
    To set this option to on, run the following command:
    # gluster volume set VOLNAME nfs.export-dirs on
  • nfs.export-dir: This option allows you to export specified subdirectories on the volume. You can export a particular subdirectory, for example:
    # gluster volume set VOLNAME nfs.export-dir /d1,/d2/d3/d4,/d6
    where d1, d2, d3, d4, d6 are the sub-directories.
    You can also control the access to mount these subdirectories based on the IP address, host name or a CIDR. For example:
    # gluster volume set VOLNAME nfs.export-dir "/d1(<ip address>),/d2/d3/d4(<host name>|<ip address>),/d6(<CIDR>)"
    The directory /d1, /d2 and /d6 are directories inside the volume. Volume name must not be added to the path. For example if the volume vol1 has directories d1 and d2, then to export these directories use the following command: gluster volume set vol1 nfs.export-dir "/d1(192.0.2.2),d2(192.0.2.34)"

7.2.1.4. Testing Volumes Mounted Using NFS

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

7.2.2. Troubleshooting NFS

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.

7.2.3. NFS-Ganesha

NFS-Ganesha is a user space file server for the NFS protocol with support for NFSv3, v4, v4.1, pNFS.
Red Hat Gluster Storage is supported with the community’s V2.2-stable release of NFS-Ganesha. The current release of Red Hat Gluster Storage introduces High Availability (HA) of NFS servers in active-active mode. pNFS is introduced as a tech preview feature. However, it does not support NFSv4 delegations and NFSv4.1.

Note

To install NFS-Ganesha refer, Deploying NFS-Ganesha on Red Hat Gluster Storage in the Red Hat Gluster Storage 3.1 Installation Guide.

Important

You must to ensure to enable the NFS firewall service along with the NFS-Ganesha firewall services. For more information NFS firewall services, see .Section 7.2, “NFS”
  • On Red Hat Enterprise Linux 7, enable the NFS-Ganesha firewall service for mountd and HA in the active zones for runtime and permanent mode using the following commands:
    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=mountd --add-service=high-availability 
      
      # firewall-cmd --zone=zone_name --add-service=mountd --add-service=high-availability --permanent
      
      # firewall-cmd --zone=public --add-port=4501/tcp --add-port=4501/udp \
      --add-port=32803/tcp --add-port=32803/udp --add-port=662/tcp --add-port=662/udp
      
      # firewall-cmd --zone=public --add-port=4501/tcp --add-port=4501/udp \
      --add-port=32803/tcp --add-port=32803/udp --add-port=662/tcp --add-port=662/udp --permanent
      
      
      • On the NFS-client machine, execute 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=892/tcp --add-port=892/udp 
        
        # firewall-cmd --zone=public --add-port=662/tcp --add-port=662/udp \
        --add-port=32803/tcp --add-port=32769/udp --add-port=892/tcp --add-port=892/udp --permanent
    3. Ensure to configure the ports mentioned above. For more information see Defining Service Ports. in Section 7.2.3.3.1 Pre-requisites to run nfs-ganesha,
The following table contains the feature matrix of the NFS support on Red Hat Gluster Storage 3.1:

Table 7.4. NFS Support Matrix

Features glusterFS NFS (NFSv3) NFS-Ganesha (NFSv3) NFS-Ganesha (NFSv4)
Root-squash Yes Yes Yes
Sub-directory exportsYes Yes Yes
LockingYes Yes Yes
Client based export permissionsYes Yes Yes
NetgroupsTech Preview Tech PreviewTech Preview
Mount protocolsUDP, TCPUDP, TCPOnly TCP
NFS transport protocolsTCPUDP, TCPTCP
AUTH_UNIXYesYesYes
AUTH_NONEYesYesYes
AUTH_KRBNoYesYes
ACLsYesNoYes
DelegationsN/AN/ANo
High availabilityYes (but no lock-recovery)YesYes
High availability (fail-back)Yes (but no lock-recovery)YesYes
Multi-headYesYesYes
Gluster RDMA volumesYesAvailable but not supportedAvailable but not supported
DRCAvailable but not supportedNoNo
Dynamic exportsNoYesYes
pseudofsN/AN/AYes
NFSv4.1N/AN/ANot Supported
NFSv4.1/pNFSN/AN/ATech Preview

Note

  • Red Hat does not recommend running NFS-Ganesha in mixed-mode and/or hybrid environments. This includes multi-protocol environments where NFS and CIFS shares are used simultaneously, or running NFS-Ganesha together with gluster-nfs, kernel-nfs or gluster-fuse clients
  • 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.

7.2.3.1. 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.

For more information about Highly Available Active-Active NFS-Ganesha, see section Highly Available Active-Active NFS-Ganesha.
pNFS (Tech-Preview)

The Parallel Network File System (pNFS) is part of the NFS v4.1 protocol that allows compute clients to access storage devices directly and in parallel.

For more information about pNFS, see section pNFS.
Dynamic Export of Volumes

Previous versions of NFS-Ganesha required a restart of the server whenever the administrator had to add or remove exports. NFS-Ganesha now 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.

Note

Modifying an export in place is currently not supported.
Exporting Multiple Entries

With this version of NFS-Ganesha, multiple Red Hat Gluster Storage volumes or sub-directories can now be exported simultaneously.

Pseudo File System

This version of NFS-Ganesha now 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.

7.2.3.2. 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.
The 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 Clustering.
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.
The Highly Available cluster is configured in the following three stages:
  1. Creating the ganesha-ha.conf file

    The ganesha-ha.conf.example 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.

    Following is an example:
    Sample ganesha-ha.conf file:
    
    # Name of the HA cluster created.
    # must be unique within the subnet
    HA_NAME="ganesha-ha-360"
    #
    # The gluster server from which to mount the shared data volume.
    HA_VOL_SERVER="server1"
    #
    # 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,server2,..."
    #HA_CLUSTER_NODES="server1.lab.redhat.com,server2.lab.redhat.com,..."
    #
    # Virtual IPs for each of the nodes specified above.
    VIP_server1="VIP_SERVER1"
    VIP_server2="VIP_SERVER2"
    #VIP_server1.lab.redhat.com="10.0.2.1"
    #VIP_server2.lab.redhat.com="10.0.2.2"
  2. Configuring NFS-Ganesha using gluster CLI

    The HA cluster can be set up or torn down using gluster CLI. In addition, it can export and unexport specific volumes. For more information, see section Configuring NFS-Ganesha using gluster CLI.

  3. Modifying the HA cluster using the ganesha-ha.sh script

    After creating the cluster, any further modification can be done using the ganesha-ha.sh script. For more information, see Modifying the HA cluster using the ganesha-ha.sh script.

7.2.3.3. Configuring NFS-Ganesha using Gluster CLI

7.2.3.3.1. 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.
  • Disable the gluster-nfs, kernel-nfs, and smbd services.
  • Edit the ganesha-ha.conf file based on your environment.
  • Create multiple virtual IPs (VIPs) on the network for each of the servers configured in the ganesha-ha.conf file and assign them to any unused NIC.
  • IPv6 must be enabled on the host interface which is used by the NFS-Ganesha daemon. To enable IPv6 support, perform the following steps:
    1. Comment or remove the line options ipv6 disable=1 in the /etc/modprobe.d/ipv6.conf file.
    2. Reboot the system.
  • 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.
  • On Red Hat Enterprise Linux 7, execute the following commands to disable and stop NetworkManager service and to enable the network service.
    # systemctl disable NetworkManager
    # systemctl stop NetworkManager
    # systemctl enable network
  • Start network service on all machines using the following command:
    For Red Hat Enterprise Linux 6:
    # service network start
    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
    
  • For Red Hat Enterprise Linux 6, install pacemaker using the following command
    # yum install pacemaker

    Note

    • For Red Hat Enterprise Linux 6, the corosync package is a dependency package of the pacemaker package and will be installed by default.
    • For Red Hat Enterprise Linux 7, pacemaker and corosync packages are installed by default when the glusterfs-ganesha package is installed.
  • Enable the pacemaker service using the following command:
    For Red Hat Enterprise Linux 6:
    # chkconfig --add pacemaker
    # chkconfig pacemaker on
    For Red Hat Enterprise Linux 7:
    # systemctl enable pacemaker.service
  • Start the pcsd service using the following command.
    For Red Hat Enterprise Linux 6:
    # service pcsd start
    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 6:
      # chkconfig --add pcsd 
      # chkconfig pcsd on
      For Red Hat Enterprise Linux 7:
      # systemctl enable pcsd
  • 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
  • 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:
    # pcs cluster 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:
    # pcs cluster auth nfs1 nfs2 nfs3 nfs4
    Username: hacluster
    Password:
    nfs1: Authorized
    nfs2: Authorized
    nfs3: Authorized
    nfs4: Authorized
  • Passwordless ssh 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/
  • As part of cluster setup, port 4501 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 = 4501;
  • Defining Service Ports

    To define the service ports, execute the following steps on every node in the nfs-ganesha cluster:

    1. Edit '/etc/ganesha/ganesha.conf' as mentioned below:
      # sed -i '/NFS_Core_Param/a \ \ \ \ \ \ \ \ MNT_Port = 20048;' /etc/ganesha/ganesha.conf
      # sed -i '/NFS_Core_Param/a \ \ \ \ \ \ \ \ NLM_Port = 32803;' /etc/ganesha/ganesha.conf
    2. Edit /etc/sysconfig/nfs file as mentioned below:
      # sed -i '/STATD_PORT/s/^#//' /etc/sysconfig/nfs
    3. Restart the statd service:
      For Red Hat Enterprise Linux 6:
      # service nfslock restart
      For Red Hat Enterprise Linux 7:
      # systemctl restart nfs-config
      # systemctl restart rpc-statd
    Execute the following steps 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
      # sed -i '/MOUNTD_PORT/s/^#//' /etc/sysconfig/nfs
    2. Restart the services:
      For Red Hat Enterprise Linux 6:
      # service nfslock restart
      # service nfs restart
      For Red Hat Enterprise Linux 7:
      # systemctl restart nfs-config
      # systemctl restart rpc-statd
      # systemctl restart nfs-mountd
      # systemctl restart nfslock
7.2.3.3.2. Configuring the HA Cluster
To setup the HA cluster, enable NFS-Ganesha by executing the following command:
# gluster nfs-ganesha enable
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 6:
# service nfslock restart
For Red Hat Enterprise Linux 7:
# systemctl restart rpc-statd
To tear down the HA cluster, execute the following command:
# gluster nfs-ganesha disable
For example,
# gluster nfs-ganesha disable
This will take a few minutes to complete. Please wait ..
nfs-ganesha : success
To verify the status of the HA cluster, execute the following script:
# /usr/libexec/ganesha/ganesha-ha.sh --status
For example:
# /usr/libexec/ganesha/ganesha-ha.sh --status

Cluster name: G1437076740.12
Last updated: Tue Jul 21 03:00:23 2015
Last change: Fri Jul 17 06:38:29 2015
Stack: corosync
Current DC: server4 (3) - partition with quorum
Version: 1.1.12-a14efad
4 Nodes configured
16 Resources configured


Online: [ server1 server2 server3 server4 ]

Full list of resources:

 Clone Set: nfs-mon-clone [nfs-mon]
     Started: [ server1 server2 server3 server4 ]
 Clone Set: nfs-grace-clone [nfs-grace]
     Started: [ server1 server2 server3 server4 ]
 server1-cluster_ip-1      (ocf::heartbeat:IPaddr):        Started server1
 server1-trigger_ip-1      (ocf::heartbeat:Dummy): Started server1
 server2-cluster_ip-1      (ocf::heartbeat:IPaddr):        Started server2

   ...output abbreviated...

Note

It is recommended to manually restart the ganesha.nfsd service after the node is rebooted, to fail back the VIPs.
7.2.3.3.3. Exporting and Unexporting Volumes through 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
Verifying the 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-6,
    # service nfs-ganesha status
    For example:
    # service nfs-ganesha status
    ganesha.nfsd (pid  4136) is running...
    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.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.log. Check the log file on noticing any unexpected behavior.

7.2.3.4. Modifying the HA cluster using the ganesha-ha.sh script

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/.
  • Adding a node to the cluster

    Before adding a node to the cluster, ensure all the prerequisites mentioned in section Pre-requisites to run NFS-Ganesha is met. 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 /etc/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 /etc/ganesha server16 10.00.00.01
    
  • 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 /etc/ganesha.
    HOSTNAME: Hostname of the new node to be added
    For example:
    # /usr/libexec/ganesha/ganesha-ha.sh --delete /etc/ganesha  server16
  • Modifying the default export configuration

    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 /etc/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 /etc/ganesha.
      volname: The name of the volume whose export configuration has to be changed.
      For example:
      # /usr/libexec/ganesha/ganesha-ha.sh --refresh-config  /etc/ganesha  testvol
      

      Note

      The export ID must not be changed.

7.2.3.5. Accessing NFS-Ganesha Exports

NFS-Ganesha exports can be accessed by mounting them in either NFSv3 or NFSv4 mode.

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.
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
Mounting exports in NFSv4 mode

To mount an export in NFSv4 mode, 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

7.2.3.6. 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.
  • By default the maximum time taken to detect if the nfs-ganesha service is down is approximately (a) 10 - 15 seconds.

    Note

    This interval 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> timeout=<timeout_value>
  • The time taken to put entire cluster to grace and then move the virtual IP (VIP) is (b) 7 seconds.
  • So the maximum total time taken to failover the VIP is (c=a+b) approximately 17 - 22 seconds. In other words, the time taken for NFS clients to detect server reboot or resume I/O is 17 - 22 seconds.
7.2.3.6.1. Modifying the Fail-over Time
Since NFS servers will be in the grace period post failover, as defined by NFS RFC, clients will try to reclaim their lost OPEN/LOCK state. For more information refer to Server Failure and Recovery Servers will block the conflicting FOPs during that period. The list of such FOPs is as below:

Table 7.5. 

Protocols FOPs
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 6

# service nfs-ganesha restart
On Red Hat Enterprise Linux 7

# systemctl restart nfs-ganesha

7.2.3.7. Configuring Kerberized NFS-Ganesha

Execute the following steps on all the machines:
  1. Install the krb5-workstation and the ntpdate packages on all the machines:
    # yum install krb5-workstation
    # yum install ntpdate

    Note

    • The krb5-libs package will be updated as a dependent package.
  2. 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
  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
  5. On the NFS-server and client, update the /etc/idmapd.conf file by making the required change. For example:
    Domain = example.com
7.2.3.7.1. 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 3.1.2 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 ;
    
            DomainName = example.com;
    }
  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 (/etc/ganesha/exports/export.vol.conf) with appropriate security flavour
  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.
7.2.3.7.2. 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.

7.2.3.8. pNFS

Important

pNFS is a technology preview feature. Technology preview features are not fully supported under Red Hat subscription level agreements (SLAs), may not be functionally complete, and are not intended for production use. However, these features provide early access to upcoming product innovations, enabling customers to test functionality and provide feedback during the development process. As Red Hat considers making future iterations of technology preview features generally available, we will provide commercially reasonable support to resolve any reported issues that customers experience when using these features.
The Parallel Network File System (pNFS) is part of the NFS v4.1 protocol that allows compute clients to access storage devices directly and in parallel. The pNFS cluster consists of Meta-Data-Server (MDS) and Data-Server (DS). The client sends all the read/write requests directly to DS and all the other operations are handled by the MDS.
Current architecture supports only single MDS and mulitple data servers. The server with which client mounts will act as MDS and all severs including MDS can act as DS
7.2.3.8.1. Prerequisites
  • Disable kernel-NFS, glusterFS-NFS servers on the system using the following commands:
    # service nfs stop
    # gluster volume set <volname> nfs.disable ON
  • Disable nfs-ganesha and tear down HA cluster via gluster CLI (only if nfs-ganesha HA cluster is already created) by executing the following command:
    # gluster features.ganesha disable
  • Turn on feature.cache-invalidation for the volume, by executing the following command:
    # gluster volume set <volname> features.cache-invalidation on
7.2.3.8.2. Configuring NFS-Ganesha for pNFS
Ensure you make the following configurations to NFS-Ganesha:
  • Configure the MDS by adding following block to the ganesha.conf file located at /etc/ganesha:
    GLUSTER
    {
     PNFS_MDS = true;
    }
  • For optimal working of pNFS, NFS-Ganesha servers should run on every node in the trusted pool using the following command:
    On RHEL 6
    # service nfs-ganesha start
    On RHEL 7
    # systemctl start nfs-ganesha
  • Verify if the volume is exported via NFS-Ganesha on all the nodes by executing the following command:
    # showmount -e localhost
7.2.3.8.2.1. Mounting Volume using pNFS
Mount the volume using NFS-Ganesha MDS server in the trusted pool using the following command.
# mount -t nfs4 -o minorversion=1 <IP-or-hostname-of-MDS-server>:/<volname> /mount-point

7.2.3.9. Manually Configuring NFS-Ganesha Exports

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.
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 /etc/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 /etc/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 section describes various configurations possible via NFS-Ganesha. Minor changes have to be made to the export.conf file to see the expected behavior.
  • Exporting Subdirectories
  • Providing Permissions for Specific Clients
  • Enabling and Disabling NFSv4 ACLs
  • Providing Pseudo Path for NFSv4 Mount
  • Providing pNFS support
Exporting Subdirectories

To export subdirectories within a volume, edit the following parameters in the export.conf file.

Path = "path_to_subdirectory";  # Path of the volume to be exported. Eg: "/test_volume/test_subdir"

 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"
  volpath = "path_to_subdirectory_with_respect_to_volume"; #Subdirectory path from the root of the volume. Eg: "/test_subdir"
 }
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.
        allow_root_access = true;
        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.
Enabling and Disabling NFSv4 ACLs

To enable NFSv4 ACLs , edit the following parameter:

Disable_ACL = FALSE;
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.

7.2.3.10. Troubleshooting

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.log
    /var/log/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 4501 is free to connect to the RQUOTA service.
    For more information see, section Manually Configuring NFS-Ganesha Exports.
  • 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.
    7. For further trouble shooting guidelines related to clustering, refer to https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/
  • 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.log
      /var/log/ganesha-gfapi.log
      /var/log/messages
    4. Ensure that dbus service is running using the following command
      # service messagebus status
  • 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:
      # pcs cluster auth <hostname>
  • 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.