3.2. Block Storage

Block storage allows the creation of high performance individual storage units. Unlike the traditional file storage capability that glusterfs supports, each storage volume/block device can be treated as an independent disk drive, so that each storage volume/block device can support an individual file system.
gluster-block is a distributed management framework for block devices. It aims to make Gluster-backed block storage creation and maintenance as simple as possible. gluster-block can provision block devices and export them as iSCSI LUN's across multiple nodes, and uses iSCSI protocol for data transfer as SCSI block/commands.

Note

  • Block volume expansion is not supported in OpenShift Container Storage 3.11.
  • Static provisioning of volumes is not supported for Block storage. Dynamic provisioning of volumes is the only method supported.
  • The recommended Red Hat Enterprise Linux (RHEL) version for block storage is RHEL-7.5.4. Please ensure that your kernel version matches with 3.10.0-862.14.4.el7.x86_64. To verify execute:
    # uname -r
    Reboot the node for the latest kernel update to take effect.

3.2.1. Dynamic Provisioning of Volumes for Block Storage

Dynamic provisioning enables you to provision a Red Hat Gluster Storage volume to a running application container without pre-creating the volume. The volume will be created dynamically as the claim request comes in, and a volume of exactly the same size will be provisioned to the application containers.

Note

The steps outlined below are not necessary when OpenShift Container Storage was deployed using the (default) Ansible installer and the default storage class (glusterfs-storage-block) created during the installation will be used.

3.2.1.1. Configuring Dynamic Provisioning of Volumes

To configure dynamic provisioning of volumes, the administrator must define StorageClass objects that describe named "classes" of storage offered in a cluster. After creating a Storage Class, a secret for heketi authentication must be created before proceeding with the creation of persistent volume claim.
3.2.1.1.1. Configuring Multipathing on all Initiators
To ensure the iSCSI initiator can communicate with the iSCSI targets and achieve HA using multipathing, execute the following steps on all the OpenShift nodes (iSCSI initiator) where the app pods are hosted:
  1. To install initiator related packages on all the nodes where initiator has to be configured, execute the following command:
    # yum install iscsi-initiator-utils device-mapper-multipath
  2. To enable multipath, execute the following command:
    # mpathconf --enable
  3. Create and add the following content to the multipath.conf file:

    Note

    In case of upgrades, make sure that the changes to multipath.conf and reloading of multipathd are done only after all the server nodes are upgraded.
    # cat >> /etc/multipath.conf <<EOF
    # LIO iSCSI
    devices {
            device {
                    vendor "LIO-ORG"
                    user_friendly_names "yes" # names like mpatha
                    path_grouping_policy "failover" # one path per group
                    hardware_handler "1 alua"
                    path_selector "round-robin 0"
                    failback immediate
                    path_checker "tur"
                    prio "alua"
                    no_path_retry 120
            }
    }
    EOF
  4. Execute the following commands to start multipath daemon and [re]load the multipath configuration:
    # systemctl start multipathd
    # systemctl reload multipathd
3.2.1.1.2. Creating Secret for Heketi Authentication
To create a secret for Heketi authentication, execute the following commands:

Note

If the admin-key value (secret to access heketi to get the volume details) was not set during the deployment of Red Hat Openshift Container Storage, then the following steps can be omitted.
  1. Create an encoded value for the password by executing the following command:
    # echo -n "<key>" | base64
    where “key” is the value for admin-key that was created while deploying CNS
    For example:
    # echo -n "mypassword" | base64
    bXlwYXNzd29yZA==
  2. Create a secret file. A sample secret file is provided below:
    # cat glusterfs-secret.yaml
    
    apiVersion: v1
    kind: Secret
    metadata:
      name: heketi-secret
      namespace: default
    data:
      # base64 encoded password. E.g.: echo -n "mypassword" | base64
      key: bXlwYXNzd29yZA==
    type: gluster.org/glusterblock
  3. Register the secret on Openshift by executing the following command:
    # oc create -f glusterfs-secret.yaml
    secret "heketi-secret" created
3.2.1.1.3. Registering a Storage Class
When configuring a StorageClass object for persistent volume provisioning, the administrator must describe the type of provisioner to use and the parameters that will be used by the provisioner when it provisions a PersistentVolume belonging to the class.
  1. Create a storage class. A sample storage class file is presented below:
    # cat > glusterfs-block-storageclass.yaml
    
    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
     name: gluster-block
    provisioner: gluster.org/glusterblock
    reclaimPolicy: Retain
    parameters:
     resturl: "http://heketi-storage-project.cloudapps.mystorage.com"
     restuser: "admin"
     restsecretnamespace: "default"
     restsecretname: "heketi-secret"
     hacount: "3"
     clusterids: "630372ccdc720a92c681fb928f27b53f,796e6db1981f369ea0340913eeea4c9a"
     chapauthenabled: "true"
     volumenameprefix: "test-vol"
    
    
    
    
    where,
    resturl: Gluster REST service/Heketi service url which provision gluster volumes on demand. The general format must be IPaddress:Port and this is a mandatory parameter for GlusterFS dynamic provisioner. If Heketi service is exposed as a routable service in openshift/kubernetes setup, this can have a format similar to http://heketi-storage-project.cloudapps.mystorage.com where the fqdn is a resolvable heketi service url.
    restuser : Gluster REST service/Heketi user who has access to create volumes in the trusted storage pool
    restsecretnamespace + restsecretname : Identification of Secret instance that contains user password to use when talking to Gluster REST service. These parameters are optional. Empty password will be used when both restsecretnamespace and restsecretname are omitted.
    hacount: It is the count of the number of paths to the block target server. hacount provides high availability via multipathing capability of iSCSI. If there is a path failure, the I/Os will not be interrupted and will be served via another available paths.
    clusterids: It is the ID of the cluster which will be used by Heketi when provisioning the volume. It can also be a list of comma-separated cluster IDs. This is an optional parameter.

    Note

    To get the cluster ID, execute the following command:
    # heketi-cli cluster list
    chapauthenabled: If you want to provision block volume with CHAP authentication enabled, this value has to be set to true. This is an optional parameter.
    volumenameprefix: This is an optional parameter. It depicts the name of the volume created by heketi. For more information see, Section 3.2.1.1.6, “(Optional) Providing a Custom Volume Name Prefix for Persistent Volumes”

    Note

    The value for this parameter cannot contain `_` in the storageclass.
  2. To register the storage class to Openshift, execute the following command:
    # oc create -f glusterfs-block-storageclass.yaml
    storageclass "gluster-block" created
  3. To get the details of the storage class, execute the following command:
    # oc describe storageclass gluster-block
    Name:        gluster-block
    IsDefaultClass:    No
    Annotations:    <none>
    Provisioner:    gluster.org/glusterblock
    Parameters:    chapauthenabled=true,hacount=3,opmode=heketi,restsecretname=heketi-secret,restsecretnamespace=default,resturl=http://heketi-storage-project.cloudapps.mystorage.com,restuser=admin
    Events:        <none>
3.2.1.1.4. Creating a Persistent Volume Claim
To create a persistent volume claim execute the following commands:
  1. Create a Persistent Volume Claim file. A sample persistent volume claim is provided below:
    # cat glusterfs-block-pvc-claim.yaml
    kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
      name: claim1
      annotations:
        volume.beta.kubernetes.io/storage-class: gluster-block
    spec:
      persistentVolumeReclaimPolicy: Retain
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 5Gi
    
    persistentVolumeReclaimPolicy:This is an optional parameter. When this parameter is set to "Retain" the underlying persistent volume is retained even after the corresponding persistent volume claim is deleted.

    Note

    When PVC is deleted, the underlying heketi and gluster volumes are not deleted if "persistentVolumeReclaimPolicy:" is set to "Retain". To delete the volume, you must use heketi cli and then delete the PV.
  2. Register the claim by executing the following command:
    # oc create -f glusterfs-block-pvc-claim.yaml
    persistentvolumeclaim "claim1" created
  3. To get the details of the claim, execute the following command:
    # oc describe pvc <claim_name>
    For example:
    # oc describe pvc claim1
    
    Name:        claim1
    Namespace:    block-test
    StorageClass:    gluster-block
    Status:        Bound
    Volume:        pvc-ee30ff43-7ddc-11e7-89da-5254002ec671
    Labels:        <none>
    Annotations:    control-plane.alpha.kubernetes.io/leader={"holderIdentity":"8d7fecb4-7dba-11e7-a347-0a580a830002","leaseDurationSeconds":15,"acquireTime":"2017-08-10T15:02:30Z","renewTime":"2017-08-10T15:02:58Z","lea...
           pv.kubernetes.io/bind-completed=yes
           pv.kubernetes.io/bound-by-controller=yes
           volume.beta.kubernetes.io/storage-class=gluster-block
           volume.beta.kubernetes.io/storage-provisioner=gluster.org/glusterblock
    Capacity:    5Gi
    Access Modes:    RWO
    Events:
     FirstSeen    LastSeen    Count    From                            SubObjectPath    Type        Reason            Message
     ---------    --------    -----    ----                            -------------    --------    ------            -------
     1m        1m        1    gluster.org/glusterblock 8d7fecb4-7dba-11e7-a347-0a580a830002            Normal        Provisioning        External provisioner is provisioning volume for claim "block-test/claim1"
     1m        1m        18    persistentvolume-controller                Normal        ExternalProvisioning    cannot find provisioner "gluster.org/glusterblock", expecting that a volume for the claim is provisioned either manually or via external software
     1m        1m        1    gluster.org/glusterblock 8d7fecb4-7dba-11e7-a347-0a580a830002            Normal        ProvisioningSucceeded    Successfully provisioned volume pvc-ee30ff43-7ddc-11e7-89da-5254002ec671
3.2.1.1.5. Verifying Claim Creation
To verify if the claim is created, execute the following commands:
  1. To get the details of the persistent volume claim and persistent volume, execute the following command:
    # oc get pv,pvc
    
    NAME                                          CAPACITY   ACCESSMODES   RECLAIMPOLICY   STATUS    CLAIM               STORAGECLASS    REASON    AGE
    pv/pvc-ee30ff43-7ddc-11e7-89da-5254002ec671   5Gi        RWO           Delete          Bound     block-test/claim1   gluster-block             3m
    
    NAME         STATUS    VOLUME                                     CAPACITY   ACCESSMODES   STORAGECLASS    AGE
    pvc/claim1   Bound     pvc-ee30ff43-7ddc-11e7-89da-5254002ec671   5Gi        RWO           gluster-block   4m
3.2.1.1.6. (Optional) Providing a Custom Volume Name Prefix for Persistent Volumes
You can provide a custom volume name prefix to the persistent volume that is created. By providing a custom volume name prefix, users can now easily search/filter the volumes based on:
  • Any string that was provided as the field value of "volnameprefix" in the storageclass file.
  • Persistent volume claim name.
  • Project / Namespace name.
To set the name, ensure that you have added the parameter volumenameprefix to the storage class file. For more information, refer Section 3.2.1.1.3, “Registering a Storage Class”

Note

The value for this parameter cannot contain `_` in the storageclass.
To verify if the custom volume name prefix is set, execute the following command:
# oc describe pv <pv_name>
For example:
# oc describe pv pvc-4e97bd84-25f4-11e8-8f17-005056a55501
    Name:            pvc-4e97bd84-25f4-11e8-8f17-005056a55501
    Labels:          <none>
    Annotations:     AccessKey=glusterblk-67d422eb-7b78-4059-9c21-a58e0eabe049-secret
                     AccessKeyNs=glusterfs
                     Blockstring=url:http://172.31.251.137:8080,user:admin,secret:heketi-secret,secretnamespace:glusterfs
                     Description=Gluster-external: Dynamically provisioned PV
                     gluster.org/type=block
                     gluster.org/volume-id=cd37c089372040eba20904fb60b8c33e
                     glusterBlkProvIdentity=gluster.org/glusterblock
                     glusterBlockShare=test-vol_glusterfs_bclaim1_4eab5a22-25f4-11e8-954d-0a580a830003
                     kubernetes.io/createdby=heketi
                     pv.kubernetes.io/provisioned-by=gluster.org/glusterblock
                     v2.0.0=v2.0.0
    StorageClass:    gluster-block-prefix
    Status:          Bound
    Claim:           glusterfs/bclaim1
    Reclaim Policy:  Delete
    Access Modes:    RWO
    Capacity:        5Gi
    Message:
    Source:
        Type:               ISCSI (an ISCSI Disk resource that is attached to a kubelet's host machine and then exposed to the pod)
        TargetPortal:       10.70.46.177
        IQN:                iqn.2016-12.org.gluster-block:67d422eb-7b78-4059-9c21-a58e0eabe049
        Lun:                0
        ISCSIInterface      default
        FSType:             xfs
        ReadOnly:           false
        Portals:            [10.70.46.142 10.70.46.4]
        DiscoveryCHAPAuth:  false
        SessionCHAPAuth:    true
        SecretRef:          {glusterblk-67d422eb-7b78-4059-9c21-a58e0eabe049-secret }
        InitiatorName:      <none>
    Events:                 <none>
The value for glusterBlockShare will have the custom volume name prefix attached to the namespace and the claim name, which is "test-vol" in this case.
3.2.1.1.7. Using the Claim in a Pod
Execute the following steps to use the claim in a pod.
  1. To use the claim in the application, for example
    # cat app.yaml
    
    apiVersion: v1
    kind: Pod
    metadata:
      name: busybox
    spec:
      containers:
        - image: busybox
          command:
            - sleep
            - "3600"
          name: busybox
          volumeMounts:
            - mountPath: /usr/share/busybox
              name: mypvc
      volumes:
        - name: mypvc
          persistentVolumeClaim:
            claimName: claim1
    # oc create -f app.yaml
    pod "busybox" created
  2. To verify that the pod is created, execute the following command:
    # oc get pods -n storage-project
    
    NAME                               READY     STATUS    RESTARTS   AGE
    block-test-router-1-deploy         0/1       Running     0          4h
    busybox                            1/1       Running   0          43s
    glusterblock-provisioner-1-bjpz4   1/1       Running   0          4h
    glusterfs-7l5xf                    1/1       Running   0          4h
    glusterfs-hhxtk                    1/1       Running   3          4h
    glusterfs-m4rbc                    1/1       Running   0          4h
    heketi-1-3h9nb                     1/1       Running   0          4h
  3. To verify that the persistent volume is mounted inside the container, execute the following command:
    # oc rsh busybox
    /  # df -h
    Filesystem                Size      Used Available Use% Mounted on
    /dev/mapper/docker-253:1-11438-39febd9d64f3a3594fc11da83d6cbaf5caf32e758eb9e2d7bdd798752130de7e
                            10.0G     33.9M      9.9G   0% /
    tmpfs                     3.8G         0      3.8G   0% /dev
    tmpfs                     3.8G         0      3.8G   0% /sys/fs/cgroup
    /dev/mapper/VolGroup00-LogVol00
                             7.7G      2.8G      4.5G  39% /dev/termination-log
    /dev/mapper/VolGroup00-LogVol00
                             7.7G      2.8G      4.5G  39% /run/secrets
    /dev/mapper/VolGroup00-LogVol00
                             7.7G      2.8G      4.5G  39% /etc/resolv.conf
    /dev/mapper/VolGroup00-LogVol00
                             7.7G      2.8G      4.5G  39% /etc/hostname
    /dev/mapper/VolGroup00-LogVol00
                             7.7G      2.8G      4.5G  39% /etc/hosts
    shm                      64.0M         0     64.0M   0% /dev/shm
    /dev/mpatha                  5.0G     32.2M      5.0G   1% /usr/share/busybox
    tmpfs                     3.8G     16.0K      3.8G   0% /var/run/secrets/kubernetes.io/serviceaccount
    tmpfs                     3.8G         0      3.8G   0% /proc/kcore
    tmpfs                     3.8G         0      3.8G   0% /proc/timer_list
    tmpfs                     3.8G         0      3.8G   0% /proc/timer_stats
    tmpfs                     3.8G         0      3.8G   0% /proc/sched_debug
3.2.1.1.8. Deleting a Persistent Volume Claim

Note

If the "persistentVolumeReclaimPolicy" parameter was set to "Retain" when registering the storageclass, the underlying PV and the corresponding volume remains even when a PVC is deleted.
  1. To delete a claim, execute the following command:
    # oc delete pvc <claim-name>
    For example:
    # oc delete pvc claim1
    persistentvolumeclaim "claim1" deleted
  2. To verify if the claim is deleted, execute the following command:
    # oc get pvc <claim-name>
    For example:
    # oc get pvc claim1
    No resources found.
    When the user deletes a persistent volume claim that is bound to a persistent volume created by dynamic provisioning, apart from deleting the persistent volume claim, Kubernetes will also delete the persistent volume, endpoints, service, and the actual volume. Execute the following commands if this has to be verified:
    • To verify if the persistent volume is deleted, execute the following command:
      # oc get pv <pv-name>
      For example:
      # oc get pv pvc-962aa6d1-bddb-11e6-be23-5254009fc65b
      No resources found.
Next step: If you are installing Red Hat Openshift Container Storage 3.11, and you want to use block storage as the backend storage for logging and metrics, proceed to Chapter 7, Gluster Block Storage as Backend for Logging and Metrics.

3.2.2. Replacing a Block on Block Storage

If you want to replace a block from a node that is out of resource or is faulty, it can be replaced to a new node.
Execute the following commands
  1. Execute the following command to fetch the zone and cluster info from heketi
    # heketi-cli topology info --user=<user> --secret=<user key>
    --user - heketi user
    --secret - Secret key for a specified user
  2. After obtaining the cluster id and zone id add a new node to heketi by executing the following command:

    Note

    Before adding the node, ensure the node is labeled as a glusterfs storage host by adding the label "glusterfs=storage-host", using the following command;
    # oc label node <NODENAME> glusterfs=storage-host
    # heketi-cli node add --zone=<zoneid> --cluster=<clusterid> --management-host-name=<new hostname> --storage-host-name=<new node ip> --user=<user> --secret=<user key>
    --cluster - The cluster in which the node should reside
    --management-host-name - Management hostname. This is the new node that has to be added.
    --storage-host-name - Storage hostname.
    --zone - The zone in which the node should reside
    --user - heketi user.
    --secret - Secret key for a specified user
    For example:
    heketi-cli node add --zone=1 --cluster=607204cb27346a221f39887a97cf3f90 --management-host-name=dhcp43-241.lab.eng.blr.redhat.com --storage-host-name=10.70.43.241 --user=admin --secret=adminkey
    
    Node information:
    Id: 2639c473a2805f6e19d45997bb18cb9c
    State: online
    Cluster Id: 607204cb27346a221f39887a97cf3f90
    Zone: 1
    Management Hostname dhcp43-241.lab.eng.blr.redhat.com
    Storage Hostname 10.70.43.241
    
  3. Execute the following command to add the device
    # heketi-cli device add --name=<device name> --node=<node id> --user=<user> --secret=<user key>
    --name - Name of device to add
    --node - Newly added node id
    For example:
    # heketi-cli device add --name=/dev/vdc --node=2639c473a2805f6e19d45997bb18cb9c --user=admin --secret=adminkey
    Device added successfully
    
  4. After the new node and its associated devices are added to heketi, the faulty or unwanted node can be removed from heketi
    To remove any node from heketi, follow this workflow:
    • node disable (Disallow usage of a node by placing it offline)
    • node replace (Removes a node and all its associated devices from Heketi)
    • device delete (Deletes a device from Heketi node)
    • node delete (Deletes a node from Heketi management)
  5. Execute the following command to fetch the node list from heketi
    #heketi-cli node list --user=<user> --secret=<user key>
    For example:
    # heketi-cli node list --user=admin --secret=adminkey
    Id:05746c562d6738cb5d7de149be1dac04    Cluster:607204cb27346a221f39887a97cf3f90
    Id:ab37fc5aabbd714eb8b09c9a868163df    Cluster:607204cb27346a221f39887a97cf3f90
    Id:c513da1f9bda528a9fd6da7cb546a1ee    Cluster:607204cb27346a221f39887a97cf3f90
    Id:e6ab1fe377a420b8b67321d9e60c1ad1    Cluster:607204cb27346a221f39887a97cf3f90
    
  6. Execute the following command to fetch the node info of the node, that has to be deleted from heketi:
    # heketi-cli node info <nodeid> --user=<user> --secret=<user key>
    For example:
    # heketi-cli node info c513da1f9bda528a9fd6da7cb546a1ee --user=admin --secret=adminkey
    Node Id: c513da1f9bda528a9fd6da7cb546a1ee
    State: online
    Cluster Id: 607204cb27346a221f39887a97cf3f90
    Zone: 1
    Management Hostname: dhcp43-171.lab.eng.blr.redhat.com
    Storage Hostname: 10.70.43.171
    Devices:
    Id:3a1e0717e6352a8830ab43978347a103   Name:/dev/vdc            State:online    Size (GiB):499     Used (GiB):100     Free (GiB):399     Bricks:1
    Id:89a57ace1c3184826e1317fef785e6b7   Name:/dev/vdd            State:online    Size (GiB):499     Used (GiB):10      Free (GiB):489     Bricks:5
    
    
  7. Execute the following command to disable the node from heketi. This makes the node go offline:
    # heketi-cli node disable <node-id> --user=<user> --secret=<user key>
    For example:
    # heketi-cli node disable ab37fc5aabbd714eb8b09c9a868163df --user=admin --secret=adminkey
    Node ab37fc5aabbd714eb8b09c9a868163df is now offline
    
  8. Execute the following command to remove a node and all its associated devices from Heketi:
    #heketi-cli node remove <node-id> --user=<user> --secret=<user key>
    For example:
    # heketi-cli node remove ab37fc5aabbd714eb8b09c9a868163df --user=admin --secret=adminkey
    Node ab37fc5aabbd714eb8b09c9a868163df is now removed
    
    
  9. Execute the following command to delete the devices from heketi node:
    # heketi-cli device delete <device-id> --user=<user> --secret=<user key>
    For example:
    # heketi-cli device delete 0fca78c3a94faabfbe5a5a9eef01b99c --user=admin --secret=adminkey
    Device 0fca78c3a94faabfbe5a5a9eef01b99c deleted
    
  10. Execute the following command to delete a node from Heketi management:
    #heketi-cli node delete <nodeid> --user=<user> --secret=<user key>
    For example:
    # heketi-cli node delete ab37fc5aabbd714eb8b09c9a868163df --user=admin --secret=adminkey
    Node ab37fc5aabbd714eb8b09c9a868163df deleted
    
  11. Execute the following commands on any one of the gluster pods to replace the faulty node with the new node:
    1. Execute the following command to get list of blockvolumes hosted under block-hosting-volume
      # gluster-block list <block-hosting-volume> --json-pretty
    2. Execute the following command to find out which all blockvolumes are hosted on the old node, with the help of info command
      # gluster-block info <block-hosting-volume>/<block-volume> --json-pretty
    3. Execute the following command to replace the faulty node with the new node:
      # gluster-block replace <volname/blockname> <old-node> <new-node> [force]
      For example:
      {
        "NAME":"block",
        "CREATE SUCCESS":"192.168.124.73",
        "DELETE SUCCESS":"192.168.124.63",
        "REPLACE PORTAL SUCCESS ON":[
          "192.168.124.79"
        ],
        "RESULT":"SUCCESS"
      }
      
      Note: If the old node is down and does not come up again then you can force replace:
      gluster-block replace sample/block 192.168.124.63 192.168.124.73 force --json-pretty
      
      {
        "NAME":"block",
        "CREATE SUCCESS":"192.168.124.73",
        "DELETE FAILED (ignored)":"192.168.124.63",
        "REPLACE PORTAL SUCCESS ON":[
          "192.168.124.79"
        ],
        "RESULT":"SUCCESS"
      }
      

    Note

    The next steps henceforth are to be executed only if the block that is to be replaced is still in use.
  12. Logout of the old portal by executing the following command on the initiator:
    # iscsiadm -m node -T <targetname> -p <old node> -u
    For example:
    # iscsiadm -m node -T iqn.2016-12.org.gluster-block:d6d18f43-8a74-4b2c-a5b7-df1fa3f5bc9a -p 192.168.124.63 -u
    Logging out of session [sid: 8, target: iqn.2016-12.org.gluster-block:d6d18f43-8a74-4b2c-a5b7-df1fa3f5bc9a, portal: 192.168.124.63,3260]
    Logout of [sid: 8, target: iqn.2016-12.org.gluster-block:d6d18f43-8a74-4b2c-a5b7-df1fa3f5bc9a, portal: 192.168.124.63,3260] successful.
  13. To re-discover the new node execute the following command:
    # iscsiadm -m discovery -t st -p <new node>
    For example:
    # iscsiadm -m discovery -t st -p 192.168.124.73
    192.168.124.79:3260,1 iqn.2016-12.org.gluster-block:d6d18f43-8a74-4b2c-a5b7-df1fa3f5bc9a
    192.168.124.73:3260,2 iqn.2016-12.org.gluster-block:d6d18f43-8a74-4b2c-a5b7-df1fa3f5bc9a
  14. Login to the new portal by executing the following command:
    # iscsiadm -m node -T <targetname> -p <new node ip> -l
    For example:
    # iscsiadm -m node -T iqn.2016-12.org.gluster-block:d6d18f43-8a74-4b2c-a5b7-df1fa3f5bc9a -p 192.168.124.73 -l
  15. To verify if the enabled hosting volume is replaced and running successfully, execute the following command on the initiator:
    # ll /dev/disk/by-path/ip-* | grep <targetname> | grep <“new node ip”>