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I have 3 node Galera Cluster on Ubuntu 18.04. As part of Ubuntu LCM, I'm upgrading my Setup to 22.04 along with this Galera MariaDB cluster will also upgrade.

I have designed below plan to upgrade my cluster using rolling upgrade.

  1. Trigger a Backup to get the latest production backup.

  2. Using wsrep_desync command stops the syncing between cluster

  3. upgrade OS and MariaDB and setup Galera on Node-1

  4. Start Mysqld on Node-1 as primary component.

  5. Restore the backup on Node-1

  6. Verify the Node-1

  7. Perform the Upgrade on node-2 and node-3 one by one.

  8. Join the node-2 and node-3 with node-1.

Please tell if I'm missing something, I have infra constrained so I can only perform rolling upgrade with minimal downtime.

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  • you should detail the mariadb version before and after the upgrade.
    – danblack
    Commented Oct 16, 2023 at 5:35
  • Mariadb version before upgrade is 10.4.12, Mariadb version after upgrade is 10.6.14 Commented Oct 17, 2023 at 6:11

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If the goal is a rolling upgrade with minimal downtime and you intend to do in-place upgrades for both DB and OS, I highly recommend doing the upgrades separately. I think it would work fine to upgrade both at the same time but I wouldn't chance it.

I also think using 'wsrep_desync' is unnecessary and might even cause problems.

For DB upgrades the procedure overview would be something like this (see MariaDB docs for detailed instructions:

  1. Stop MariaDB on node 1
  2. Reinstall new SQL version on node 1
  3. Upgrade tables and verify membership in the cluster
  4. Repeat for other nodes

This allows the cluster to retain 2 active nodes at all times. The cluster is expected to remain operational with a mix of different SQL versions participating in it. However, if you run into trouble, you can always revert manually or by snapshot, VM export, disk image, etc. You should also note that when rejoining the cluster, it may take some extra time to get back in sync.

The OS procedure would be largely the same, with the note that you might need to reinstall MariaDB after the upgrade. So far in my testing, the cluster seems to be perfectly happy to have mixed OS versions among its members.

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