Chapter 3. Upgrading RHCS 6 to RHCS 8 involving RHEL 8 to RHEL 9 upgrades with stretch mode enabled

Procedure

1. Log into the Cephadm shell:

   Example

   [ceph: root@host01 /]# cephadm shell

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2. Label a second node as the admin in the cluster to manage the cluster when the admin node is re-provisioned.

   Syntax

   ceph orch host label add HOSTNAME _admin

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   Example

   [ceph: root@host01 /]# ceph orch host label add host02_admin

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3. Set the noout flag.

   Example

   [ceph: root@host01 /]# ceph osd set noout

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4. Drain all the daemons from the host:

   Syntax

   ceph orch host drain HOSTNAME --force

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   Example

   [ceph: root@host01 /]# ceph orch host drain host02 --force

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   The _no_schedule label is automatically applied to the host which blocks deployment.

5. Check if all the daemons are removed from the storage cluster:

   Syntax

   ceph orch ps HOSTNAME

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   Example

   [ceph: root@host01 /]# ceph orch ps host02

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6. Zap the devices so that if the hosts being drained have OSDs present, then they can be used to re-deploy OSDs when the host is added back.

   Syntax

   ceph orch device zap HOSTNAME DISK --force

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   Example

   [ceph: root@host01 /]# ceph orch device zap ceph-host02 /dev/vdb --force
   
   zap successful for /dev/vdb on ceph-host02

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7. Check the status of OSD removal:

   Example

   [ceph: root@host01 /]# ceph orch osd rm status

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   When no placement groups (PG) are left on the OSD, the OSD is decommissioned and removed from the storage cluster.

8. Remove the host from the cluster:

   Syntax

   ceph orch host rm HOSTNAME --force

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   Example

   [ceph: root@host01 /]# ceph orch host rm host02 --force

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9. Re-provision the respective hosts from RHEL 8 to RHEL 9 as described in Upgrading from RHEL 8 to RHEL 9.

10. Run the preflight playbook with the --limit option:

    Syntax

    ansible-playbook -i INVENTORY_FILE cephadm-preflight.yml --limit NEWHOST_NAME

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    Example

    [ceph: root@host01 /]# ansible-playbook -i hosts cephadm-preflight.yml --extra-vars "ceph_origin={storage-product}" --limit host02

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    The preflight playbook installs podman, lvm2, chronyd, and cephadm on the new host. After installation is complete, cephadm resides in the /usr/sbin/ directory.

11. Extract the cluster’s public SSH keys to a folder:

    Syntax

    ceph cephadm get-pub-key ~/PATH

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    Example

    [ceph: root@host01 /]# ceph cephadm get-pub-key ~/ceph.pub

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12. Copy Ceph cluster’s public SSH keys to the re-provisioned node:

    Syntax

    ssh-copy-id -f -i ~/PATH root@HOST_NAME_2

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    Example

    [ceph: root@host01 /]# ssh-copy-id -f -i ~/ceph.pub root@host02

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    1. Optional: If the removed host has a monitor daemon, then, before adding the host to the cluster, add the --unmanaged flag to monitor deployment.

       Syntax

       ceph orch apply mon PLACEMENT --unmanaged

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13. Add the host again to the cluster and add the labels present earlier:

    Syntax

    ceph orch host add HOSTNAME IP_ADDRESS --labels=LABELS

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    1. Optional: If the removed host had a monitor daemon deployed originally, the monitor daemon needs to be added back manually with the location attributes as described in Replacing the tiebreaker with a new monitor.

       Syntax

       ceph mon add HOSTNAME IP LOCATION

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       Example

       [ceph: root@host01 /]# ceph mon add ceph-host02 10.0.211.62 datacenter=DC2

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       Syntax

       ceph orch daemon add mon HOSTNAME

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       Example

       [ceph: root@host01 /]# ceph orch daemon add mon ceph-host02

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14. Verify the daemons on the re-provisioned host running successfully with the same ceph version:

    Syntax

    ceph orch ps

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15. Set back the monitor daemon placement to managed.

    Syntax

    ceph orch apply mon PLACEMENT

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16. Repeat the above steps for all hosts.

    1. The arbiter monitor cannot be drained or removed from the host. Therefor, the arbiter mon needs to be re-provisioned to another tie-breaker node, and then drained or removed from host as described in Replacing the tiebreaker with a new monitor.
17. Follow the same approach to re-provision admin nodes and use a second admin node to manage clusters.
18. Add the backup files again to the node.
19. . Add admin nodes again to cluster using the second admin node. Set the mon deployment to unmanaged.
20. Re-add the old arbiter monintor and remove the temporary monitor created earlier. For more information, see Replacing the tiebreaker with a new monitor.

21. Unset the noout flag.

    Syntax

    ceph osd unset noout

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22. Verify the Ceph version and the cluster status to ensure that all demons are working as expected after the Red Hat Enterprise Linux upgrade.
23. Follow Upgrade a Red Hat Ceph Storage cluster using `cephadm` to perform a Red Hat Ceph Storage 6 to Red Hat Ceph Storage 8 upgrade.