Chapter 16. Replacing storage devices

Procedure

1. Identify the OSD that needs to be replaced and the OpenShift Container Platform node that has the OSD scheduled on it.

   $ oc get -n openshift-storage pods -l app=rook-ceph-osd -o wide

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   Example output:

   rook-ceph-osd-0-6d77d6c7c6-m8xj6    0/1    CrashLoopBackOff    0    24h   10.129.0.16   compute-2   <none>           <none>
   rook-ceph-osd-1-85d99fb95f-2svc7    1/1    Running             0    24h   10.128.2.24   compute-0   <none>           <none>
   rook-ceph-osd-2-6c66cdb977-jp542    1/1    Running             0    24h   10.130.0.18   compute-1   <none>           <none>

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   In this example, rook-ceph-osd-0-6d77d6c7c6-m8xj6 needs to be replaced and compute-2 is the OpenShift Container platform node on which the OSD is scheduled.

   Note

   If the OSD to be replaced is healthy, the status of the pod will be Running.

2. Scale down the OSD deployment for the OSD to be replaced.

   $ osd_id_to_remove=0
   $ oc scale -n openshift-storage deployment rook-ceph-osd-${osd_id_to_remove} --replicas=0

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   where, osd_id_to_remove is the integer in the pod name immediately after the rook-ceph-osd prefix. In this example, the deployment name is rook-ceph-osd-0.

   Example output:

   deployment.extensions/rook-ceph-osd-0 scaled

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3. Verify that the rook-ceph-osd pod is terminated.

   $ oc get -n openshift-storage pods -l ceph-osd-id=${osd_id_to_remove}

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   Example output:

   No resources found.

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   Note

   If the rook-ceph-osd pod is in terminating state, use the force option to delete the pod.

   $ oc delete pod rook-ceph-osd-0-6d77d6c7c6-m8xj6 --force --grace-period=0

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   Example output:

   warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.
     pod "rook-ceph-osd-0-6d77d6c7c6-m8xj6" force deleted

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4. Incase, the persistent volume associated with the failed OSD fails, get the failed persistent volumes details and delete them using the following commands:

   $ oc get pv
   $ oc delete pv <failed-pv-name>

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5. Remove the old OSD from the cluster so that a new OSD can be added.

   1. Delete any old ocs-osd-removal jobs.

      $ oc delete -n openshift-storage job ocs-osd-removal-${osd_id_to_remove}

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      Example output:

      job.batch "ocs-osd-removal-0" deleted

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   2. Change to the openshift-storage project.

      $ oc project openshift-storage

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   3. Remove the old OSD from the cluster.

      $ oc process -n openshift-storage ocs-osd-removal -p FAILED_OSD_IDS=${osd_id_to_remove} FORCE_OSD_REMOVAL=false |oc create -n openshift-storage -f -

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      You can add comma separated OSD IDs in the command to remove more than one OSD. (For example, FAILED_OSD_IDS=0,1,2).

      The FORCE_OSD_REMOVAL value must be changed to “true” in clusters that only have three OSDs, or clusters with insufficient space to restore all three replicas of the data after the OSD is removed.

      Warning

      This step results in OSD being completely removed from the cluster. Ensure that the correct value of osd_id_to_remove is provided.

6. Verify that the OSD was removed successfully by checking the status of the ocs-osd-removal-job pod.

   A status of Completed confirms that the OSD removal job succeeded.

   # oc get pod -l job-name=ocs-osd-removal-job -n openshift-storage

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7. Ensure that the OSD removal is completed.

   $ oc logs -l job-name=ocs-osd-removal-job -n openshift-storage --tail=-1 | egrep -i 'completed removal'

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   Example output:

   2022-05-10 06:50:04.501511 I | cephosd: completed removal of OSD 0

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   Important

   If the ocs-osd-removal-job fails and the pod is not in the expected Completed state, check the pod logs for further debugging.

   For example:

   # oc logs -l job-name=ocs-osd-removal-job -n openshift-storage --tail=-1

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8. If encryption was enabled at the time of install, remove dm-crypt managed device-mapper mapping from the OSD devices that are removed from the respective OpenShift Data Foundation nodes.

   1. Get PVC name(s) of the replaced OSD(s) from the logs of ocs-osd-removal-job pod :

      $ oc logs -l job-name=ocs-osd-removal-job -n openshift-storage --tail=-1  |egrep -i ‘pvc|deviceset’

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      For example:

      2021-05-12 14:31:34.666000 I | cephosd: removing the OSD PVC "ocs-deviceset-xxxx-xxx-xxx-xxx"

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   2. For each of the nodes identified in step #1, do the following:

      1. Create a debug pod and chroot to the host on the storage node.

         $ oc debug node/<node name>
         $ chroot /host

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      2. Find relevant device name based on the PVC names identified in the previous step

         sh-4.4# dmsetup ls| grep <pvc name>
         ocs-deviceset-xxx-xxx-xxx-xxx-block-dmcrypt (253:0)

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      3. Remove the mapped device.

         $ cryptsetup luksClose --debug --verbose ocs-deviceset-xxx-xxx-xxx-xxx-block-dmcrypt

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         Note

         If the above command gets stuck due to insufficient privileges, run the following commands:

         • Press CTRL+Z to exit the above command.

         • Find PID of the process which was stuck.

           $ ps -ef | grep crypt

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         • Terminate the process using kill command.

           $ kill -9 <PID>

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         • Verify that the device name is removed.

           $ dmsetup ls

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9. Delete the ocs-osd-removal job.

   $ oc delete -n openshift-storage job ocs-osd-removal-${osd_id_to_remove}

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   Example output:

   job.batch "ocs-osd-removal-0" deleted

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Verfication steps

1. Verify that there is a new OSD running.

   $ oc get -n openshift-storage pods -l app=rook-ceph-osd

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   Example output:

   rook-ceph-osd-0-5f7f4747d4-snshw                                  1/1     Running     0          4m47s
   rook-ceph-osd-1-85d99fb95f-2svc7                                  1/1     Running     0          1d20h
   rook-ceph-osd-2-6c66cdb977-jp542                                  1/1     Running     0          1d20h

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2. Verify that there is a new PVC created which is in Bound state.

   $ oc get -n openshift-storage pvc

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   Example output:

   NAME                           STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                  AGE
   db-noobaa-db-0                 Bound    pvc-b44ebb5e-3c67-4000-998e-304752deb5a7   50Gi       RWO            ocs-storagecluster-ceph-rbd   6d
   ocs-deviceset-0-data-0-gwb5l   Bound    pvc-bea680cd-7278-463d-a4f6-3eb5d3d0defe   512Gi      RWO            standard                      94s
   ocs-deviceset-1-data-0-w9pjm   Bound    pvc-01aded83-6ef1-42d1-a32e-6ca0964b96d4   512Gi      RWO            standard                      6d
   ocs-deviceset-2-data-0-7bxcq   Bound    pvc-5d07cd6c-23cb-468c-89c1-72d07040e308   512Gi      RWO            standard                      6d

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3. Optional: If cluster-wide encryption is enabled on the cluster, verify that the new OSD devices are encrypted.

   1. Identify the nodes where the new OSD pods are running.

      $ oc get -n openshift-storage -o=custom-columns=NODE:.spec.nodeName pod/_<OSD-pod-name>_

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      <OSD-pod-name>

      Is the name of the OSD pod.

      For example:

      $ oc get -n openshift-storage -o=custom-columns=NODE:.spec.nodeName pod/rook-ceph-osd-0-544db49d7f-qrgqm

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      Example output:

      NODE
      compute-1

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   2. For each of the nodes identified in previous step, do the following:

      1. Create a debug pod and open a chroot environment for the selected host(s).

         $ oc debug node/<node name>
         $ chroot /host

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      2. Run “lsblk” and check for the “crypt” keyword beside the ocs-deviceset name(s)

         $ lsblk

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4. Log in to OpenShift Web Console and view the storage dashboard.

   Figure 16.1. OSD status in OpenShift Container Platform storage dashboard after device replacement