Chapter 4. Upgrading RHCS 5 to RHCS 6 involving RHEL 8 to RHEL 9 upgrades with stretch mode enabled

You can perform an upgrade from Red Hat Ceph Storage 5 to Red Hat Ceph Storage 6 involving Red Hat Enterprise Linux 8 to Red Hat Enterprise Linux 9 with the stretch mode enabled.

Important

Upgrade to the latest version of Red Hat Ceph Storage 5.3.z5 prior to upgrading to the latest version Red Hat Ceph Storage 6.1.

Prerequisites

Red Hat Ceph Storage 5 on Red Hat Enterprise Linux 8 with necessary hosts and daemons running with stretch mode enabled.
Backup of Ceph binary (/usr/sbin/cephadm), ceph.pub (/etc/ceph), and the Ceph cluster’s public SSH keys from the admin node.

Note

Arbiter monitor cannot be drained or removed from the host. Hence, 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

Procedure

Log into the Cephadm shell:
Example
```
[ceph: root@host01 /]# cephadm shell
```
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
```
Example
```
[ceph: root@host01 /]# ceph orch host label add host02 admin
```

Set the noout flag.

Example

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

Drain all the daemons from the host:
Syntax
```
ceph orch host drain HOSTNAME --force
```
Example
```
[ceph: root@host01 /]# ceph orch host drain host02 --force
```
The _no_schedule label is automatically applied to the host which blocks deployment.
Check if all the daemons are removed from the storage cluster:
Syntax
```
ceph orch ps HOSTNAME
```
Example
```
[ceph: root@host01 /]# ceph orch ps host02
```
Check the status of OSD removal:
Example
```
[ceph: root@host01 /]# ceph orch osd rm status
```
When no placement groups (PG) are left on the OSD, the OSD is decommissioned and removed from the storage cluster.

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]

Example

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

zap successful for /dev/vdb on ceph-host02

Remove the host from the cluster:

Syntax

ceph orch host rm HOSTNAME --force

Example

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

Re-provision the respective hosts from RHEL 8 to RHEL 9 as described in Upgrading from RHEL 8 to RHEL 9.
Run the preflight playbook with the --limit option:
Syntax
```
ansible-playbook -i INVENTORY_FILE cephadm-preflight.yml --limit NEWHOST_NAME
```
Example
```
[ceph: root@host01 /]# ansible-playbook -i hosts cephadm-preflight.yml --extra-vars "ceph_origin={storage-product}" --limit host02
```
The preflight playbook installs podman, lvm2, chronyd, and cephadm on the new host. After installation is complete, cephadm resides in the /usr/sbin/ directory.

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

Syntax

ceph cephadm get-pub-key ~/PATH

Example

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

Copy Ceph cluster’s public SSH keys to the re-provisioned node:
Syntax
```
ssh-copy-id -f -i ~/PATH root@HOST_NAME_2
```
Example
```
[ceph: root@host01 /]# ssh-copy-id -f -i ~/ceph.pub root@host02
```
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
```
Add the host again to the cluster and add the labels present earlier:
Syntax
```
ceph orch host add HOSTNAME IP_ADDRESS --labels=LABELS
```
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
```
  Example
```
[ceph: root@host01 /]# ceph mon add ceph-host02 10.0.211.62 datacenter=DC2
```
  Syntax
```
ceph orch daemon add mon HOSTNAME
```
  Example
```
[ceph: root@host01 /]# ceph orch daemon add mon ceph-host02
```
Verify the daemons on the re-provisioned host running successfully with the same ceph version:
Syntax
```
ceph orch ps
```
Set back the monitor daemon placement to managed.
Note
This step needs to be done one by one.
Syntax
```
ceph orch apply mon PLACEMENT
```
Repeat the above steps for all hosts.
Follow the same approach to re-provision admin nodes and use a second admin node to manage clusters.
Add the backup files again to the node.
. Add admin nodes again to cluster using the second admin node. Set the mon deployment to unmanaged.
Follow Replacing the tiebreaker with a new monitor to add back the old arbiter mon and remove the temporary mon created earlier.
Unset the noout flag.
Syntax
```
ceph osd unset noout
```
Verify the Ceph version and the cluster status to ensure that all demons are working as expected after the Red Hat Enterprise Linux upgrade.
Now that the RHEL OS is successfully upgraded, follow Upgrade a Red Hat Ceph Storage cluster using cephadm to perform Red Hat Ceph Storage 5 to Red Hat Ceph Storage 6 Upgrade.

Chapter 4. Upgrading RHCS 5 to RHCS 6 involving RHEL 8 to RHEL 9 upgrades with stretch mode enabled

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