Chapter 10. The Ceph iSCSI Gateway

As a storage administrator, you can install and configure an iSCSI gateway for the Red Hat Ceph Storage cluster. With Ceph’s iSCSI gateway you can effectively run a fully integrated block-storage infrastructure with all features and benefits of a conventional Storage Area Network (SAN).

Warning

SCSI persistent reservations are not supported. Mapping multiple iSCSI initiators to an RBD image is supported, if using a cluster aware file system or clustering software that does not rely on SCSI persistent reservations. For example, VMware vSphere environments using ATS is supported, but using Microsoft’s clustering server (MSCS) is not supported.

10.1. Introduction to the Ceph iSCSI gateway

Traditionally, block-level access to a Ceph storage cluster has been limited to QEMU and librbd, which is a key enabler for adoption within OpenStack environments. Block-level access to the Ceph storage cluster can now take advantage of the iSCSI standard to provide data storage.

The iSCSI gateway integrates Red Hat Ceph Storage with the iSCSI standard to provide a highly available (HA) iSCSI target that exports RADOS Block Device (RBD) images as SCSI disks. The iSCSI protocol allows clients, known as initiators, to send SCSI commands to SCSI storage devices, known as targets, over a TCP/IP network. This allows for heterogeneous clients, such as Microsoft Windows, to access the Red Hat Ceph Storage cluster.

Figure 10.1. Ceph iSCSI Gateway

Ceph iSCSI gateway

10.2. Requirements for the iSCSI target

The Red Hat Ceph Storage Highly Available (HA) iSCSI gateway solution has requirements for the number of gateway nodes, memory capacity, and timer settings to detect down OSDs.

Required Number of Nodes

Install a minimum of two iSCSI gateway nodes. To increase resiliency and I/O handling, install up to four iSCSI gateway nodes.

Memory Requirements

The memory footprint of the RBD images can grow to a large size. Each RBD image mapped on the iSCSI gateway nodes uses roughly 90 MB of memory. Ensure the iSCSI gateway nodes have enough memory to support each mapped RBD image.

Detecting Down OSDs

There are no specific iSCSI gateway options for the Ceph Monitors or OSDs, but it is important to lower the default timers for detecting down OSDs to reduce the possibility of initiator timeouts.

Additional Resources

10.3. Installing the iSCSI gateway

As a storage administrator, before you can utilize the benefits of the Ceph iSCSI gateway, you must install the required software packages. You can install the Ceph iSCSI gateway by using the command-line interface.

Each iSCSI gateway runs the Linux I/O target kernel subsystem (LIO) to provide iSCSI protocol support. LIO utilizes a user-space passthrough (TCMU) to interact with the Ceph librbd library to expose RBD images to iSCSI clients. With the Ceph iSCSI gateway you can effectively run a fully integrated block-storage infrastructure with all features and benefits of a conventional Storage Area Network (SAN).

10.3.1. Prerequisites

  • Red Hat Enterprise Linux 8.4 or higher.
  • A running Red Hat Ceph Storage 5 or higher cluster.

10.3.2. Installing the Ceph iSCSI gateway using the command-line interface

The Ceph iSCSI gateway is the iSCSI target node and also a Ceph client node. The Ceph iSCSI gateway can be a standalone node or be colocated on a Ceph Object Store Disk (OSD) node. Complete the following steps to install the Ceph iSCSI gateway.

Prerequisites

  • Red Hat Enterprise Linux 8.4 or higher
  • A Red Hat Ceph Storage 5 cluster or higher
  • If the Ceph iSCSI gateway is not colocated on an OSD node, copy the Ceph configuration files, located in the /etc/ceph/ directory, from a running Ceph node in the storage cluster to the all iSCSI Gateway nodes. The Ceph configuration files must exist on the iSCSI gateway nodes under /etc/ceph/.
  • On all Ceph iSCSI gateway nodes, enable the Ceph Tools repository.
  • On all Ceph iSCSI gateway nodes, install and configure the Ceph command-line interface.
  • If needed, open TCP ports 3260 and 5000 on the firewall on all Ceph iSCSI nodes.
  • Create a new or use an existing RADOS Block Device (RBD).

Procedure

  1. Retrieve the information of the iSCSI container on the host:

    Example

    [root@iscsigw ~]# podman ps

  2. Log into the Cephadm shell:

    Example

    [root@iscsigw ~]# cephadm shell

  3. Optional: On all Ceph iSCSI gateway nodes, install and configure the OpenSSL utility, if needed.

    1. Install the openssl package:

      Example

      [ceph: root@iscsigw /]# yum install openssl

    2. On the primary iSCSI gateway node, create a directory to hold the SSL keys:

      Example

      [ceph: root@iscsigw /]# mkdir ~/ssl-keys
      [ceph: root@iscsigw /]# cd ~/ssl-keys

    3. On the primary iSCSI gateway node, create the certificate and key files. Enter the environmental information when prompted.

      [ceph: root@iscsigw /]# openssl req -newkey rsa:2048 -nodes -keyout iscsi-gateway.key -x509 -days 365 -out iscsi-gateway.crt
    4. On the primary iSCSI gateway node, create a PEM file:

      [ceph: root@iscsigw /]# cat iscsi-gateway.crt iscsi-gateway.key > iscsi-gateway.pem
    5. On the primary iSCSI gateway node, create a public key:

      [ceph: root@iscsigw /]# openssl x509 -inform pem -in iscsi-gateway.pem -pubkey -noout > iscsi-gateway-pub.key
    6. From the primary iSCSI gateway node, copy the iscsi-gateway.crt, iscsi-gateway.pem, iscsi-gateway-pub.key, and iscsi-gateway.key files to the /etc/ceph/ directory on the other iSCSI gateway nodes.
  4. Create a configuration file on a Ceph iSCSI gateway node.

    1. Create a file named iscsi-gateway.yaml in the /etc/ceph/ directory:

      [ceph: root@iscsigw /]# touch /etc/ceph/iscsi-gateway.yaml
    2. Edit the iscsi-gateway.yaml file and add the following lines:

      Syntax

      service_type: iscsi
      service_id: iscsi
      placement:
        hosts:
          - HOST_NAME
          - HOST_NAME_
      spec:
        pool: POOL_NAME  # RADOS pool where ceph-iscsi config data is stored.
        trusted_ip_list: "IP_ADDRESS_1,IP_ADDRESS_2"

      Example

      service_type: iscsi
      service_id: iscsi
      placement:
        hosts:
        - [host01,host02.]
      spec:
        pool: iscsipool1
        trusted_ip_list: "IP_ADDRESS_1,IP_ADDRESS_2,IP_ADDRESS_3,..."

  5. Change the path to /etc/ceph/ and apply the specification with the following command:

    Example

    [ceph: root@iscsigw /]# ceph orch apply -i iscsi-gateway.yaml

  6. Next, configure targets, LUNs, and clients. See the Configuring the iSCSI target using the command-line interface section for details.

Additional Resources

10.4. Configuring the iSCSI target

As a storage administrator, you can configure targets, LUNs, and clients, using the gwcli command-line utility. You can also optimize performance of the iSCSI target, use the gwcli reconfigure subcommand.

Warning

Red Hat does not support managing Ceph block device images exported by the Ceph iSCSI gateway tools, such as gwcli.. Also, using the rbd command to rename or remove RBD images exported by the Ceph iSCSI gateway, can result in an unstable storage cluster.

Warning

Before removing RBD images from the iSCSI gateway configuration, follow the standard procedures for removing a storage device from the operating system. For details, see the link:Removing a storage device chapter in the Storage Administration Guide for Red Hat Enterprise Linux 7 or the System Design Guide for Red Hat Enterprise Linux 8.

10.4.1. Prerequisites

  • Installation of the Ceph iSCSI gateway software.

10.4.2. Configuring the iSCSI target using the command-line interface

The Ceph iSCSI gateway is the iSCSI target node and also a Ceph client node. Configure the Ceph iSCSI gateway either on a standalone node, or colocate it with a Ceph Object Storage Device (OSD) node.

Warning

Do not adjust other options using the gwcli reconfigure subcommand unless specified in this document or Red Hat Support has instructed you to do so.

Prerequisites

  • Installation of the Ceph iSCSI gateway software.

Procedure

  1. Retrieve the information of the iSCSI container running on the host:

    Example

    [root@iscsigw ~]# podman ps
    [root@iscsigw ~]# podman exec -it 4b5ffb814409 /bin/bash

  2. Start the iSCSI gateway command-line interface:

    [root@iscsigw ~]# gwcli
  3. Navigate to the iscsi-targets directory:

    Example

    [root@iscsigw ~]# cd /iscsi-targets

  4. Create the iSCSI gateways using either IPv4 or IPv6 addresses:

    Syntax

    >/iscsi-targets create iqn.2003-01.com.redhat.iscsi-gw:_target_name_
    > goto gateways
    > create ISCSI_GW_NAME IP_ADDR_OF_GW
    > create ISCSI_GW_NAME IP_ADDR_OF_GW

    Example

    >/iscsi-targets create iqn.2003-01.com.redhat.iscsi-gw:ceph-igw
    > goto gateways
    > create ceph-gw-1 10.172.19.21
    > create ceph-gw-2 10.172.19.22

  5. Add a Ceph block device:

    Syntax

    > cd /disks
    >/disks/ create POOL_NAME image=IMAGE_NAME size=IMAGE_SIZE_m|g|t

    Example

    > cd /disks
    >/disks/ create rbd image=disk_1 size=50g

    Note

    Do not use any periods (.) in the pool or image name.

  6. Create a client:

    Syntax

    > goto hosts
    > create iqn.1994-05.com.redhat:_client_name_
    > auth use username=USER_NAME password=PASSWORD

    Example

    > goto hosts
    > create iqn.1994-05.com.redhat:rh7-client
    > auth username=iscsiuser1 password=temp12345678

    Important

    Red Hat does not support mixing clients, some with Challenge Handshake Authentication Protocol (CHAP) enabled and some CHAP disabled. All clients must have either CHAP enabled or have CHAP disabled. The default behavior is to only authenticate an initiator by its initiator name.

    If initiators are failing to log into the target, the CHAP authentication might not be configured correctly for some initiators, for example:

    o- hosts ................................ [Hosts: 2: Auth: MISCONFIG]

    Use the following command at the hosts level to reset all the CHAP authentication:

    /> goto hosts
    /iscsi-target...csi-igw/hosts> auth nochap
    ok
    ok
    /iscsi-target...csi-igw/hosts> ls
    o- hosts ................................ [Hosts: 2: Auth: None]
      o- iqn.2005-03.com.ceph:esx ........... [Auth: None, Disks: 4(310G)]
      o- iqn.1994-05.com.redhat:rh7-client .. [Auth: None, Disks: 0(0.00Y)]
  7. Add disks to a client:

    Syntax

    >/iscsi-target..eph-igw/hosts
    > cd iqn.1994-05.com.redhat:_CLIENT_NAME_
    > disk add POOL_NAME/IMAGE_NAME

    Example

    >/iscsi-target..eph-igw/hosts
    > cd iqn.1994-05.com.redhat:rh7-client
    > disk add rbd/disk_1

  8. To confirm that the API is using SSL correctly, search the rbd-target-api log file, located at /var/log/rbd-target-api.log or /var/log/rbd-target/rbd-target-api.log, for https, for example:

    Aug 01 17:27:42 test-node.example.com python[1879]:  * Running on https://0.0.0.0:5000/
  9. Verifying that the Ceph ISCSI gateways are working:

    /> goto gateways
    /iscsi-target...-igw/gateways> ls
    o- gateways ............................ [Up: 2/2, Portals: 2]
      o- ceph-gw-1  ........................ [ 10.172.19.21 (UP)]
      o- ceph-gw-2  ........................ [ 10.172.19.22 (UP)]

    If the status is UNKNOWN, check for network issues and any misconfigurations. If using a firewall, verify that the appropriate TCP port is open. Verify that the iSCSI gateway is listed in the trusted_ip_list option. Verify that the rbd-target-api service is running on the iSCSI gateway node.

  10. Optionally, reconfigure the max_data_area_mb option:

    Syntax

    >/disks/ reconfigure POOL_NAME/IMAGE_NAME max_data_area_mb NEW_BUFFER_SIZE

    Example

    >/disks/ reconfigure rbd/disk_1 max_data_area_mb 64

    Note

    The max_data_area_mb option controls the amount of memory in megabytes that each image can use to pass SCSI command data between the iSCSI target and the Ceph cluster. If this value is too small, it can result in excessive queue full retries which will affect performance. If the value is too large, it can result in one disk using too much of the system memory, which can cause allocation failures for other subsystems. The default value for the max_data_area_mb option is 8.

  11. Configure an iSCSI initiator.

Additional Resources

10.4.3. Optimize the performance of the iSCSI Target

There are many settings that control how the iSCSI Target transfers data over the network. These settings can be used to optimize the performance of the iSCSI gateway.

Warning

Only change these settings if instructed to by Red Hat Support or as specified in this document.

The gwcli reconfigure subcommand controls the settings that are used to optimize the performance of the iSCSI gateway.

Settings that affect the performance of the iSCSI target

max_data_area_mb
Description
The size of kernel data ring buffer in megabytes.
Type
Integer
Default
8
cmdsn_depth
Description
Indicates the depth of the queue that controls maximum I/O.
Type
Integer
Default
128
immediate_data
Description
Indicates if the initiator requests permission from the target to transmit immediate data whenever it establishes a new session. If this value is Yes, the initiator requests permission from the target to transmit immediate data whenever it establishes a new session.
Type
Boolean
Default
Yes
initial_r2t
Description
Indicates if the host bus adapter (HBA) initiator requests permission from the target to transmit unsolicited SCSI data whenever it establishes a new session. If this member is Yes, the HBA initiator requests permission from the target to transmit unsolicited SCSI data whenever it establishes a new session.
Type
Boolean
Default
Yes
max_outstanding_r2t
Description
The maximum number of outstanding ready to transfer (R2T) requests for each task, excluding the first R2T that initiates the task.
Type
Integer
Default
1
first_burst_length
Description
The maximum amount of unsolicited data an iSCSI initiator can send to the target during the execution of a single SCSI command.
Type
Integer in bytes
Default
262144
max_burst_length
Description
The maximum SCSI data payload in an input PDU sequence or a solicited output PDU sequence.
Type
Integer in bytes
Default
524288
max_recv_data_segment_length
Description
The maximum number of data bytes the initiator can receive in an iSCSI PDU from a target.
Type
Integer in bytes
Default
262144
max_xmit_data_segment_length
Description
The maximum number of data bytes the initiator sends in an iSCSI PDU to the target.
Type
Integer in bytes
Default
0

Additional Resources

10.4.4. Configuring iSCSI host groups using the command-line interface

The Ceph iSCSI gateway can configure host groups for managing multiple servers that share the same disk configuration. iSCSI host groups creates a logical grouping of hosts and the disks that each host in the group has access to.

Important

The sharing of disk devices to multiple hosts must use a cluster-aware file system.

Prerequisites

  • Installation of the Ceph iSCSI gateway software.
  • Root-level access to the Ceph iSCSI gateway node.

Procedure

  1. Retrieve the information of the iSCSI container running on the host:

    Example

    [root@iscsigw ~] podman ps
    CONTAINER ID  IMAGE                                           COMMAND   CREATED    STATUS  PORTS  NAMES
    4b5ffb814409  registry.redhat.io/rhceph-alpha/rhceph-5-rhel8:latest    2 hours ago         Up 2 hours ago ceph-f838eb7a-597c-11eb-b0a9-525400e2439c-iscsi.iscsi.cephLab2-node-01.anaahg

  2. Use the iSCSI container ID to enter into the container:

    Example

    [root@iscsigw ~]# podman exec -it 4b5ffb814409 /bin/bash

  3. Run the gwcli command:

    [ceph: root@iscsigw /]# gwcli
  4. Create a new host group:

    Syntax

    cd iscsi-targets/
    cd IQN/host-groups
    create group_name=GROUP_NAME

    Example

    /> cd iscsi-targets/
    /iscsi-targets> cd iqn.2003-01.com.redhat.iscsi-gw:ceph-igw/host-groups/
    /iscsi-target.../host-groups> create group_name=igw_grp01

  5. Add a host to the host group:

    Important

    Ensure that you remove all the disks that are added to the host, before adding the host to the host group otheriwse, a host cannot be added to the hostgroup.

    Syntax

    cd GROUP_NAME
    host add client_iqn=CLIENT_IQN

    Example

    > cd igw_grp01
    /iscsi-target.../host-groups/igw_grp01> host add client_iqn=iqn.1994-05.com.redhat:rh8-client

    Repeat this step to add additional hosts to the group.

  6. Add a disk to the host group:

    Syntax

    cd /disks/
    /disks> create pool=POOL image=IMAGE_NAME size=SIZE
    cd /IQN/host-groups/GROUP_NAME
    disk add POOL/IMAGE_NAME

    Example

    > cd /disks/
    /disks> create pool=rbd image=rbdimage size=1G
    /> cd iscsi-targets/iqn.2003-01.com.redhat.iscsi-gw:ceph-igw/host-groups/igw_grp01/
    /iscsi-target...s/igw_grp01> disk add rbd/rbdimage

    Repeat this step to add additional disks to the group.

10.4.5. Additional Resources

  • For details on configuring iSCSI targets using the Red Hat Ceph Storage Dashboard, see the Creating iSCSI targets section in the Red Hat Ceph Storage Dashboard Guide.

10.5. Configuring the iSCSI initiator

You can configure the iSCSI initiator to connect to the Ceph iSCSI gateway on the following platforms.

10.5.1. Configuring the iSCSI initiator for Red Hat Enterprise Linux

Prerequisites

  • Red Hat Enterprise Linux 7.7 or higher.
  • Package iscsi-initiator-utils-6.2.0.873-35 or newer must be installed.
  • Package device-mapper-multipath-0.4.9-99 or newer must be installed.

Procedure

  1. Install the iSCSI initiator and multipath tools:

    [root@rhel ~]# yum install iscsi-initiator-utils
    [root@rhel ~]# yum install device-mapper-multipath
  2. Set the initiator name by editing the /etc/iscsi/initiatorname.iscsi file. Note that the initiator name must match the initiator name that was used during the initial setup using the gwcli command.
  3. Configure multipath I/O.

    1. Create the default /etc/multipath.conf file and enable the multipathd service:

      [root@rhel ~]# mpathconf --enable --with_multipathd y
    2. Update the /etc/multipath.conf file as follows:

      devices {
              device {
                      vendor                 "LIO-ORG"
                      product                "TCMU device"
                      hardware_handler       "1 alua"
                      path_grouping_policy   "failover"
                      path_selector          "queue-length 0"
                      failback               60
                      path_checker           tur
                      prio                   alua
                      prio_args              exclusive_pref_bit
                      fast_io_fail_tmo       25
                      no_path_retry          queue
              }
      }
    3. Restart the multipathd service:

      [root@rhel ~]# systemctl reload multipathd
  4. Set up CHAP and iSCSI discovery and login.

    1. Provide a CHAP user name and password by updating the /etc/iscsi/iscsid.conf file accordingly, for example:

      node.session.auth.authmethod = CHAP
      node.session.auth.username = user
      node.session.auth.password = password
    2. Discover the target portals:

      Syntax

      iscsiadm -m discovery -t st -p IP_ADDR

    3. Log in to target:

      Syntax

      iscsiadm -m node -T TARGET -l

  5. View the multipath I/O configuration. The multipathd daemon sets up devices automatically based on the settings in the multipath.conf file.

    1. Use the multipath command to show devices setup in a failover configuration with a priority group for each path, for example:

      Example

      [root@rhel ~]# multipath -ll
      mpathbt (360014059ca317516a69465c883a29603) dm-1 LIO-ORG,TCMU device
      size=1.0G features='0' hwhandler='1 alua' wp=rw
      |-+- policy='queue-length 0' prio=50 status=active
      | `- 28:0:0:1 sde  8:64  active ready running
      `-+- policy='queue-length 0' prio=10 status=enabled
        `- 29:0:0:1 sdc  8:32  active ready running

      The multipath -ll output prio value indicates the ALUA state, where prio=50 indicates it is the path to the owning iSCSI gateway in the ALUA Active-Optimized state and prio=10 indicates it is an Active-non-Optimized path. The status field indicates which path is being used, where active indicates the currently used path, and enabled indicates the failover path, if the active fails.

    2. To match the device name, for example, sde in the multipath -ll output, to the iSCSI gateway:

      Example

      [root@rhel ~]# iscsiadm -m session -P 3

      The Persistent Portal value is the IP address assigned to the iSCSI gateway listed in the gwcli utility.

10.5.2. Configuring the iSCSI initiator for Red Hat Virtualization

Prerequisites

  • Red Hat Virtualization 4.1
  • Configured MPIO devices on all Red Hat Virtualization nodes
  • The iscsi-initiator-utils-6.2.0.873-35 package or newer
  • The device-mapper-multipath-0.4.9-99 package or newer

Procedure

  1. Configure multipath I/O.

    1. Create the default /etc/multipath.conf file and enable the multipathd service:

      [root@rhv ~]# mpathconf --enable --with_multipathd y
    2. Update the /etc/multipath.conf file as follows:

      devices {
              device {
                      vendor                 "LIO-ORG"
                      product                "TCMU device"
                      hardware_handler       "1 alua"
                      path_grouping_policy   "failover"
                      path_selector          "queue-length 0"
                      failback               60
                      path_checker           tur
                      prio                   alua
                      prio_args              exclusive_pref_bit
                      fast_io_fail_tmo       25
                      no_path_retry          queue
              }
      }
    3. Restart the multipathd service:

      [root@rhv ~]# systemctl reload multipathd
  2. Click the Storage resource tab to list the existing storage domains.
  3. Click the New Domain button to open the New Domain window.
  4. Enter the Name of the new storage domain.
  5. Use the Data Center drop-down menu to select an data center.
  6. Use the drop-down menus to select the Domain Function and the Storage Type. The storage domain types that are not compatible with the chosen domain function are not available.
  7. Select an active host in the Use Host field. If this is not the first data domain in a data center, you must select the data center’s SPM host.
  8. The New Domain window automatically displays known targets with unused LUNs when iSCSI is selected as the storage type. If the target that you are adding storage from is not listed then you can use target discovery to find it, otherwise proceed to the next step.

    1. Click Discover Targets to enable target discovery options. When targets have been discovered and logged in to, the New Domain window automatically displays targets with LUNs unused by the environment. Note that LUNs external to the environment are also displayed. You can use the Discover Targets options to add LUNs on many targets, or multiple paths to the same LUNs.
    2. Enter the fully qualified domain name or IP address of the iSCSI host in the Address field.
    3. Enter the port to connect to the host on when browsing for targets in the Port field. The default is 3260.
    4. If the Challenge Handshake Authentication Protocol (CHAP) is being used to secure the storage, select the User Authentication check box. Enter the CHAP user name and CHAP password.
    5. Click the Discover button.
    6. Select the target to use from the discovery results and click the Login button. Alternatively, click the Login All to log in to all of the discovered targets.

      Important

      If more than one path access is required, ensure to discover and log in to the target through all the required paths. Modifying a storage domain to add additional paths is currently not supported.

  9. Click the + button next to the desired target. This will expand the entry and display all unused LUNs attached to the target.
  10. Select the check box for each LUN that you are using to create the storage domain.
  11. Optionally, you can configure the advanced parameters.

    1. Click Advanced Parameters.
    2. Enter a percentage value into the Warning Low Space Indicator field. If the free space available on the storage domain is below this percentage, warning messages are displayed to the user and logged.
    3. Enter a GB value into the Critical Space Action Blocker field. If the free space available on the storage domain is below this value, error messages are displayed to the user and logged, and any new action that consumes space, even temporarily, will be blocked.
    4. Select the Wipe After Delete check box to enable the wipe after delete option. You can edit this option after creating the domain, but doing so does not change the wipe after delete property of disks that already exist.
    5. Select the Discard After Delete check box to enable the discard after delete option. You can edit this option after creating the domain. This option is only available to block storage domains.
  12. Click OK to create the storage domain and close the window.

10.5.3. Configuring the iSCSI initiator for Microsoft Windows

Prerequisites

  • Microsoft Windows Server 2016

Procedure

  1. Install the iSCSI initiator and configure discovery and setup.

    1. Install the iSCSI initiator driver and MPIO tools.
    2. Launch the MPIO program, click the Discover Multi-Paths tab, check the Add support for iSCSI devices box, and click Add.
    3. Reboot the MPIO program.
    4. On the iSCSI Initiator Properties window, on the Discovery tab 1 , add a target portal. Enter the IP address or DNS name 2 and Port 3 of the Ceph iSCSI gateway:

      iscsi discovery tab mod
    5. On the Targets tab 1 , select the target and click Connect 2 :

      iscsi target tab mod
    6. On the Connect To Target window, select the Enable multi-path option 1 , and click the Advanced button 2 :

      iscsi connect to target mod
    7. Under the Connect using section, select a Target portal IP 1 . Select Enable CHAP login on 2 and enter the Name and Target secret values 3 from the Ceph iSCSI client credentials section, and click OK 4 :

      iscsi advanced window mod
      Important

      Windows Server 2016 does not accept a CHAP secret less than 12 bytes.

    8. Repeat the previous two steps for each target portal defined when setting up the iSCSI gateway.
    9. If the initiator name is different than the initiator name used during the initial setup, rename the initiator name. From iSCSI Initiator Properties window, on the Configuration tab 1 , click the Change button 2 to rename the initiator name.

      iscsi windows initiator properties mod
  2. Set up multipath I/O. In PowerShell, use the PDORemovePeriod command to set the MPIO load balancing policy and the mpclaim command to set the load balancing policy. The iSCSI Initiator Tool configures the remaining options.

    Note

    Red Hat recommends increasing the PDORemovePeriod option to 120 seconds from PowerShell. You might need to adjust this value based on the application. When all paths are down, and 120 seconds expires, the operating system starts failing I/O requests.

    Set-MPIOSetting -NewPDORemovePeriod 120
    1. Set the failover policy

      mpclaim.exe -l -m 1
    2. Verify the failover policy

      mpclaim -s -m
      MSDSM-wide Load Balance Policy: Fail Over Only
    3. Using the iSCSI Initiator tool, from the Targets tab 1 click on the Devices…​ button 2 :

      iscsi target tab2 mod
    4. From the Devices window, select a disk 1 and click the MPIO…​ button 2 :

      iscsi devices mpio mod
    5. The Device Details window displays the paths to each target portal. The Load Balancing Policy Fail Over Only must be selected.

      mpio set failover only mod
    6. View the multipath configuration from the PowerShell:

      mpclaim -s -d MPIO_DISK_ID

      Replace MPIO_DISK_ID with the appropriate disk identifier.

      Note

      There is one Active/Optimized path which is the path to the iSCSI gateway node that owns the LUN, and there is an Active/Unoptimized path for each other iSCSI gateway node.

      mpclaim output mod
  3. Optionally, tune the settings. Consider using the following registry settings:

    • Windows Disk Timeout

      Key

      HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk

      Value

      TimeOutValue = 65

    • Microsoft iSCSI Initiator Driver

      Key

      HKEY_LOCAL_MACHINE\\SYSTEM\CurrentControlSet\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}\<Instance_Number>\Parameters

      Values

      LinkDownTime = 25
      SRBTimeoutDelta = 15

10.5.4. Configuring the iSCSI initiator for VMware ESXi

Prerequisites

  • See the iSCSI Gateway (IGW) section in the Customer Portal Knowledgebase article for supported VMware ESXi versions.
  • Access to the VMware ESXi web interface.
  • Root access to VMware ESXi host console to execute the esxcli command.

Procedure

  1. Log into the VMware ESXi web interface.
  2. Click on Actions → highlight Services → click Enable SSH.
  3. Log into the VMware ESXi host console, and disable HardwareAcceleratedMove (XCOPY):

    > esxcli system settings advanced set --int-value 0 --option /DataMover/HardwareAcceleratedMove
  4. From the VMware ESXi web interface, on the Navigator pane, click Storage. Click on the Adapters tab. Highlight the adapter, and click on Configure iSCSI.
  5. Verify the initiator name in the Name & alias field.
  6. If the initiator name is different than the initiator name used when creating the client during the initial setup using the gwcli utility, then change the initiator name. From the VMware ESXi host console, do the following steps.

    1. Get the adapter name for the iSCSI software:

      > esxcli iscsi adapter list
      > Adapter  Driver     State   UID            Description
      > -------  ---------  ------  -------------  ----------------------
      > vmhba64  iscsi_vmk  online  iscsi.vmhba64  iSCSI Software Adapter
    2. Set the initiator name:

      Syntax

      esxcli iscsi adapter set -A ADAPTOR_NAME -n INITIATOR_NAME

      Example

      > esxcli iscsi adapter set -A vmhba64 -n iqn.1994-05.com.redhat:rh8-client

    3. Verify the new initiator name from the VMware ESXi web interface. Click Storage in the Navigator pane. Click Software iSCSI. The new initiator name is in the Name & alias field, along with the Ceph Object Gateway node names.
  7. Expand the CHAP authentication section. From the drop-down list, select Do not use CHAP unless required by target. Enter the CHAP Name and Secret credentials that were used in the initial setup. Verify the Mutual CHAP authentication section has Do not use CHAP selected.

    Warning

    Due to a bug in the VMware host client, the CHAP settings are not used initially. On the Ceph iSCSI gateway node, the kernel logs include the following errors as an indication of this bug:

    > kernel: CHAP user or password not set for Initiator ACL
    > kernel: Security negotiation failed.
    > kernel: iSCSI Login negotiation failed.

    To work around this bug, configure the CHAP settings using the esxcli command. The authname argument is the Name in the CHAP authentication section:

    Syntax

    esxcli iscsi adapter auth chap set --direction=uni --authname=ISCSI_USER_NAME --secret=ISCSI_PASSWORD --level=discouraged -A ADAPTOR_NAME

  8. Expand Advanced settings section. Set the RecoveryTimeout value to 25.
  9. In the Dynamic targets section, click on Add dynamic target. Under the Address field click to add an IP addresses for one of the Ceph iSCSI gateways. Only one IP address needs to be added. Finally, click the Save configuration button. Click on the Devices tab to see the RBD image.

    Note

    LUN is configured automatically, using the ALUA SATP and MRU PSP. Do not use other SATPs and PSPs. You can verify this by the esxcli command:

    Syntax

    esxcli storage nmp path list -d eui.DEVICE_ID

    Replace DEVICE_ID with the appropriate device identifier.

  10. From the VMware ESXi host console, verify that multipathing is set up correctly.

    1. List the devices:

      Example

      > esxcli storage nmp device list | grep iSCSI
         Device Display Name: LIO-ORG iSCSI Disk (naa.6001405f8d087846e7b4f0e9e3acd44b)
         Device Display Name: LIO-ORG iSCSI Disk (naa.6001405057360ba9b4c434daa3c6770c)

    2. Get the multipath information for the Ceph iSCSI disk from the previous step:

      Example

      > esxcli storage nmp path list -d naa.6001405f8d087846e7b4f0e9e3acd44b
      
      iqn.2005-03.com.ceph:esx1-00023d000001,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,t,1-naa.6001405f8d087846e7b4f0e9e3acd44b
         Runtime Name: vmhba64:C0:T0:L0
         Device: naa.6001405f8d087846e7b4f0e9e3acd44b
         Device Display Name: LIO-ORG iSCSI Disk (naa.6001405f8d087846e7b4f0e9e3acd44b)
         Group State: active
         Array Priority: 0
         Storage Array Type Path Config: {TPG_id=1,TPG_state=AO,RTP_id=1,RTP_health=UP}
         Path Selection Policy Path Config: {current path; rank: 0}
      
      iqn.2005-03.com.ceph:esx1-00023d000002,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,t,2-naa.6001405f8d087846e7b4f0e9e3acd44b
         Runtime Name: vmhba64:C1:T0:L0
         Device: naa.6001405f8d087846e7b4f0e9e3acd44b
         Device Display Name: LIO-ORG iSCSI Disk (naa.6001405f8d087846e7b4f0e9e3acd44b)
         Group State: active unoptimized
         Array Priority: 0
         Storage Array Type Path Config: {TPG_id=2,TPG_state=ANO,RTP_id=2,RTP_health=UP}
         Path Selection Policy Path Config: {non-current path; rank: 0}

      From the example output, each path has an iSCSI or SCSI name with the following parts:

      Initiator name = iqn.2005-03.com.ceph:esx1 ISID = 00023d000002 Target name = iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw Target port group = 2 Device id = naa.6001405f8d087846e7b4f0e9e3acd44b

      The Group State value of active indicates this is the Active-Optimized path to the iSCSI gateway. The gwcli command lists the active as the iSCSI gateway owner. The rest of the paths have the Group State value of unoptimized and are the failover path, if the active path goes into a dead state.

    3. To match all paths to their respective iSCSI gateways:

      Example

      > esxcli iscsi session connection list
      vmhba64,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,00023d000001,0
         Adapter: vmhba64
         Target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw
         ISID: 00023d000001
         CID: 0
         DataDigest: NONE
         HeaderDigest: NONE
         IFMarker: false
         IFMarkerInterval: 0
         MaxRecvDataSegmentLength: 131072
         MaxTransmitDataSegmentLength: 262144
         OFMarker: false
         OFMarkerInterval: 0
         ConnectionAddress: 10.172.19.21
         RemoteAddress: 10.172.19.21
         LocalAddress: 10.172.19.11
         SessionCreateTime: 08/16/18 04:20:06
         ConnectionCreateTime: 08/16/18 04:20:06
         ConnectionStartTime: 08/16/18 04:30:45
         State: logged_in
      
      vmhba64,iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw,00023d000002,0
         Adapter: vmhba64
         Target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw
         ISID: 00023d000002
         CID: 0
         DataDigest: NONE
         HeaderDigest: NONE
         IFMarker: false
         IFMarkerInterval: 0
         MaxRecvDataSegmentLength: 131072
         MaxTransmitDataSegmentLength: 262144
         OFMarker: false
         OFMarkerInterval: 0
         ConnectionAddress: 10.172.19.22
         RemoteAddress: 10.172.19.22
         LocalAddress: 10.172.19.12
         SessionCreateTime: 08/16/18 04:20:06
         ConnectionCreateTime: 08/16/18 04:20:06
         ConnectionStartTime: 08/16/18 04:30:41
         State: logged_in

      Match the path name with the ISID value, and the RemoteAddress value is the IP address of the owning iSCSI gateway.

  11. From the VMware ESXi web interface, click on the Devices tab to see the iSCSI disk.
  12. Click on New datastore to start the wizard.

    1. Provide a name for the new datastore, and click Next.
    2. Select Use full disk, and click Next.
    3. Click Finish. A warning message appears about erasing the disk. Click Yes to proceed, and create the new datastore.
    4. The new datastore will appear on the Datastores tab.
  13. You can check disk usage by selecting the datastore name. You can also check disk usage from Ceph by running the following command:

    Syntax

    rbd du --pool POOL_NAME

    Example

    [root@rbd-client ~]# rbd du --pool rbdpool

10.6. Managing iSCSI services

The ceph-iscsi package installs the configuration management logic, and the rbd-target-gw and rbd-target-api systemd services.

The rbd-target-api service restores the Linux iSCSI target state at startup, and responds to ceph-iscsi REST API calls from tools like gwcli and Red Hat Ceph Storage Dashboard. The rbd-target-gw service provides metrics using the Prometheus plug-in.

The rbd-target-api service assumes it is the only user of the Linux kernel’s target layer. Do not use the target service installed with the targetcli package when using rbd-target-api.

Procedure

  1. To start the services:

    # systemctl start rbd-target-api
    # systemctl start rbd-target-gw
  2. To restart the services:

    # systemctl restart rbd-target-api
    # systemctl restart rbd-target-gw
  3. To reload the services:

    # systemctl reload rbd-target-api
    # systemctl reload rbd-target-gw

    The reload request forces rbd-target-api to reread the configuration and apply it to the current running environment.

  4. To stop the services:

    # systemctl stop rbd-target-api
    # systemctl stop rbd-target-gw

    The stop request closes the gateway’s portal interfaces, dropping connections to clients and wipes the current Linux iSCSI target configuration from the kernel. This returns the iSCSI gateway to a clean state. When clients are disconnected, active I/O is rescheduled to the other iSCSI gateways by the client side multipathing layer.

10.7. Adding more iSCSI gateways

As a storage administrator, you can expand the initial two iSCSI gateways to four iSCSI gateways by using the gwcli command-line tool or the Red Hat Ceph Storage Dashboard. Adding more iSCSI gateways provides you more flexibility when using load-balancing and failover options, along with providing more redundancy.

10.7.1. Prerequisites

  • A running Red Hat Ceph Storage 5 cluster
  • Spare nodes or existing OSD nodes
  • root permissions

10.7.2. Using gwcli to add more iSCSI gateways

You can use the gwcli command-line tool to add more iSCSI gateways. This procedure expands the default of two iSCSI gateways to four iSCSI gateways.

Prerequisites

  • Red Hat Enterprise Linux 7.7 or later.
  • A running Red Hat Ceph Storage cluster.
  • Installation of the iSCSI gateway software.
  • Having root user access to the new nodes or OSD nodes.

Procedure

  1. If the Ceph iSCSI gateway is not colocated on an OSD node, copy the Ceph configuration files, located in the /etc/ceph/ directory, from a running Ceph node in the storage cluster to the new iSCSI Gateway node. The Ceph configuration files must exist on the iSCSI gateway node under the /etc/ceph/ directory.
  2. Install and configure the Ceph command-line interface.
  3. On the new iSCSI gateway nodes, enable the Red Hat Ceph Storage Tools repository:

    Red Hat Enterprise Linux 7

    [root@iscsigw ~]# subscription-manager repos --enable=rhel-7-server-rhceph-4-tools-rpms

    Red Hat Enterprise Linux 8

    [root@iscsigw ~]# subscription-manager repos --enable=rhceph-4-tools-for-rhel-8-x86_64-rpms

  4. Install the ceph-iscsi, and tcmu-runner packages:

    Red Hat Enterprise Linux 7

    [root@iscsigw ~]# yum install ceph-iscsi tcmu-runner

    Red Hat Enterprise Linux 8

    [root@iscsigw ~]# dnf install ceph-iscsi tcmu-runner

    1. If needed, install the openssl package:

      Red Hat Enterprise Linux 7

      [root@iscsigw ~]# yum install openssl

      Red Hat Enterprise Linux 8

      [root@iscsigw ~]# dnf install openssl

  5. On one of the existing iSCSI gateway nodes, edit the /etc/ceph/iscsi-gateway.cfg file and append the trusted_ip_list option with the new IP addresses for the new iSCSI gateway nodes. For example:

    [config]
    ...
    trusted_ip_list = 10.172.19.21,10.172.19.22,10.172.19.23,10.172.19.24
  6. Copy the updated /etc/ceph/iscsi-gateway.cfg file to all the iSCSI gateway nodes.

    Important

    The iscsi-gateway.cfg file must be identical on all iSCSI gateway nodes.

  7. Optionally, if using SSL, also copy the ~/ssl-keys/iscsi-gateway.crt, ~/ssl-keys/iscsi-gateway.pem, ~/ssl-keys/iscsi-gateway-pub.key, and ~/ssl-keys/iscsi-gateway.key files from one of the existing iSCSI gateway nodes to the /etc/ceph/ directory on the new iSCSI gateway nodes.
  8. Enable and start the API service on the new iSCSI gateway nodes:

    [root@iscsigw ~]# systemctl enable rbd-target-api
    [root@iscsigw ~]# systemctl start rbd-target-api
  9. Start the iSCSI gateway command-line interface:

    [root@iscsigw ~]# gwcli
  10. Creating the iSCSI gateways using either IPv4 or IPv6 addresses:

    Syntax

    >/iscsi-target create iqn.2003-01.com.redhat.iscsi-gw:_TARGET_NAME_
    > goto gateways
    > create ISCSI_GW_NAME IP_ADDR_OF_GW
    > create ISCSI_GW_NAME IP_ADDR_OF_GW

    Example

    >/iscsi-target create iqn.2003-01.com.redhat.iscsi-gw:ceph-igw
    > goto gateways
    > create ceph-gw-3 10.172.19.23
    > create ceph-gw-4 10.172.19.24

  11. From the iSCSI initiators, re-login to use the newly added iSCSI gateways.

Additional Resources

10.8. Verifying that the initiator is connected to the iSCSI target

After installing the iSCSI gateway and configuring the iSCSI target and an initiator, verify that the initiator is properly connected to the iSCSI target.

Prerequisites

  • Installation of the Ceph iSCSI gateway software.
  • Configured the iSCSI target.
  • Configured the iSCSI initiator.

Procedure

  1. Start the iSCSI gateway command-line interface:

    [root@iscsigw ~]# gwcli
  2. Verify that the initiator is connected the iSCSI target:

    /> goto hosts
    /iscsi-target...csi-igw/hosts> ls
    o- hosts .............................. [Hosts: 1: Auth: None]
      o- iqn.1994-05.com.redhat:rh7-client  [LOGGED-IN, Auth: None, Disks: 0(0.00Y)]

    The initiator status is LOGGED-IN if it is connected.

  3. Verify that LUNs are balanced across iSCSI gateways:

    /> goto hosts
    /iscsi-target...csi-igw/hosts> ls
    o- hosts ................................. [Hosts: 2: Auth: None]
      o- iqn.2005-03.com.ceph:esx ............ [Auth: None, Disks: 4(310G)]
      | o- lun 0 ............................. [rbd.disk_1(100G), Owner: ceph-gw-1]
      | o- lun 1 ............................. [rbd.disk_2(10G), Owner: ceph-gw-2]

    When creating a disk, the disk is assigned an iSCSI gateway as its Owner based on what gateways have the lowest number of mapped LUNs. If this number is balanced, gateways are assigned based on a round robin allocation. Currently, the balancing of LUNs is not dynamic and cannot be selected by the user.

    When the initiator is logged into the target, and the multipath layer is in a optimized state, the initiator’s operating system multipath utilities report the path to the Owner gateway as being in ALUA Active-Optimized (AO) state. The multipath utilities report the other paths as being in the ALUA Active-non-Optimized (ANO) state.

    If the AO path fails, one of the other iSCSI gateways is used. The ordering for the failover gateway depends on the initiator’s multipath layer, where normally, the order is based on which path was discovered first.

10.9. Upgrading the Ceph iSCSI gateway using the command-line interface

Upgrading the Red Hat Ceph Storage iSCSI gateways can be done in a rolling fashion, by upgrading one bare-metal iSCSI gateway node at a time.

Warning

Do not upgrade the iSCSI gateway while upgrading and restarting Ceph OSDs. Wait until the OSD upgrades are finished and the storage cluster is in an active+clean state.

Prerequisites

  • A running Ceph iSCSI gateway.
  • A running Red Hat Ceph Storage cluster.
  • Having root access to the iSCSI gateway node.

Procedure

  1. Update the iSCSI gateway packages:

    [root@iscsigw ~]# yum update ceph-iscsi
  2. Stop the iSCSI gateway daemons:

    [root@iscsigw ~]# systemctl stop rbd-target-api
    [root@iscsigw ~]# systemctl stop rbd-target-gw
  3. Verify that the iSCSI gateway daemons stopped cleanly:

    [root@iscsigw ~]# systemctl status rbd-target-gw
    1. If the rbd-target-gw service successfully stops, then skip to step 4.
    2. If the rbd-target-gw service fails to stop, then do the following steps:

      1. If the targetcli package is not install, then install the targetcli package:

        [root@iscsigw ~]# yum install targetcli
      2. Check for existing target objects:

        [root@iscsigw ~]# targetcli ls

        Example

        o- / ............................................................. [...]
        o- backstores .................................................... [...]
        | o- user:rbd ..................................... [Storage Objects: 0]
        o- iscsi .................................................. [Targets: 0]

        If the backstores and Storage Objects are empty, then the iSCSI target has been shutdown cleanly and you can skip to step 4.

      3. If you have still have target objects, use the following command to force remove all target objects:

        [root@iscsigw ~]# targetcli clearconfig confirm=True
        Warning

        If multiple services are using the iSCSI target, use targetcli in interactive mode to delete those specific objects.

  4. Update the tcmu-runner package:

    [root@iscsigw ~]# yum update tcmu-runner
  5. Stop the tcmu-runner service:

    [root@iscsigw ~]# systemctl stop tcmu-runner
  6. Restart the iSCSI gateway services in the following order:

    [root@iscsigw ~]# systemctl start tcmu-runner
    [root@iscsigw ~]# systemctl start rbd-target-gw
    [root@iscsigw ~]# systemctl start rbd-target-api

10.10. Monitoring the iSCSI gateways

Red Hat Ceph Storage cluster now incorporates a generic metric gathering framework within the OSDs and MGRs to provide built-in monitoring. The metrics are generated within the Red Hat Ceph Storage cluster and there is no need to access client nodes to scrape metrics.

To monitor the performance of RBD images, Ceph has a built-in MGR Prometheus exporter module to translate individual RADOS object metrics into aggregated RBD image metrics for Input/Output(I/O) operations per second, throughput, and latency. The Ceph iSCSI gateway also provides a Prometheus exporter for Linux-IO (LIO) level performance metrics, supporting monitoring and visualization tools like Grafana. These metrics include the information about defined Target Portal Groups (TPGs) and mapped Logical Unit Numbers (LUNs), per LUN state and the number of Input Output operations per second (IOPS), read bytes and write bytes per LUN per client. By default, the Prometheus exporter is enabled.

You can change the default settings by using the following options in the iscsi-gateway.cfg:

Example

[config]

prometheus_exporter = True
prometheus_port = 9287
prometheus_host = xx.xx.xx.xxx

Note

The gwtop tool used for Ceph iSCSI gateway environments to monitor performance of exported Ceph block device (RBD) images is deprecated.

Additional Resources

  • For details how to monitor iSCSI gateways using the Red Hat Ceph Storage Dashboard, see the iSCSI functions section in the Red Hat Ceph Storage Dashboard Guide.

10.11. Removing the iSCSI configuration

To remove the iSCSI configuration, use the gwcli utility to remove hosts and disks.

Prerequisites

  • Disconnect all iSCSI initiators:

    • Red Hat Enterprise Linux initiators:

      Syntax

      iscsiadm -m node -T TARGET_NAME --logout

      Replace TARGET_NAME with the configured iSCSI target name, for example:

      Example

      # iscsiadm -m node -T iqn.2003-01.com.redhat.iscsi-gw:ceph-igw --logout
      Logging out of session [sid: 1, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.21,3260]
      Logging out of session [sid: 2, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.22,3260]
      Logout of [sid: 1, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.21,3260] successful.
      Logout of [sid: 2, target: iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw, portal: 10.172.19.22,3260] successful.

    • Windows initiators:

      See the Microsoft documentation for more details.

    • VMware ESXi initiators:

      See the VMware documentation for more details.

Procedure

  1. Run the iSCSI gateway command line utility:

    [root@iscsigw ~]# gwcli
  2. Remove the hosts:

    Syntax

    /> cd /iscsi-target/iqn.2003-01.com.redhat.iscsi-gw:$TARGET_NAME/hosts
    /> /iscsi-target...TARGET_NAME/hosts> delete CLIENT_NAME

    Replace TARGET_NAME with the configured iSCSI target name, and replace CLIENT_NAME with iSCSI initiator name, for example:

    Example

    /> cd /iscsi-target/iqn.2003-01.com.redhat.iscsi-gw:ceph-igw/hosts
    /> /iscsi-target...eph-igw/hosts> delete iqn.1994-05.com.redhat:rh7-client

  3. Remove the disks:

    Syntax

    /> cd /disks/
    /disks> delete POOL_NAME.IMAGE_NAME

    Replace POOL_NAME with the name of the pool and the IMAGE_NAME with the name of the image, for example:

    Example

    /> cd /disks/
    /disks> delete rbd.disk_1

10.12. Additional Resources

  • For details on managing iSCSI gateway using the Red Hat Ceph Storage Dashboard, see the iSCSI functions section in the Dashboard Guide for Red Hat Ceph Storage 5.