MariaDB Galera Cluster Upgrade Path

Fri, 2020-12-18 10:47 — Shinguz

Because we conduct many customers in MariaDB Galera Cluster upgrades and because these customers sometimes have pretty old MariaDB Galera Cluster set-ups I think it is good to have a rough MariaDB Galera Cluster Upgrade Path.

For an Upgrade Path we have to consider a few things:

We face different MariaDB Galera Cluster version (5.5, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5 and soon 10.6).
We face different Galera plug-in versions (v2, v3 and v4). Direct upgrade from v2 to v4 is not possible. Upgrade from latest lower version to higher version is supported.
We should upgrade to the newest version of a Release Series first before upgrading to the next major Release Series.
MariaDB supports skipping of Major Release Series in general but we should consider the Galera plug-in as well.
New versions in a Release Series can have new bugs.
We should make sure that also application side MariaDB connectors are ready for the new version and not only the MariaDB database server. In MariaDB this is a bit less of an issue than with MySQL but it can happen as well (see 10.4.17).
Upgrading with dump/restore (without the mysql schema) should always work also skipping Major Release Series or Galera versions.
Following the Upgrade Path can take 3 to 7 steps. So it makes sense to not postpone upgrades too long into the future!
To reduce impact on service and having better testing possibilities use traditional Master (old) → Slave (new) Replication.
To not get a kick in the teeth you should test your MariaDB Galera Cluster Upgrade carefully (see for example 10.3.27, 10.4.16 and 10.4.17 (MDEV-24229, MDEV-23851 and MDEV-24406)).
Do NOT forget to always run mysql_upgrade/mariadb-upgrade after each and every upgrade!

MariaDB Galera Cluster Upgrade from 5.5 to 10.0

At these times we had the change from Galera 2 to Galera 3. You should upgrade to the newest MariaDB 5.5 version first and then do the upgrade to MariaDB 10.0:

If you are upgrading from the most recent MariaDB Galera Cluster 5.5 release to MariaDB Galera Cluster 10.0, then the versions will be compatible. The latest releases of MariaDB Galera Cluster 5.5 and MariaDB Galera Cluster 10.0 use Galera 3, so they should be compatible. [ 2 ]

If a direct upgrade from 5.5 to 10.3 (or any intermediate major version) is working you should test carefully!

MariaDB Galera Cluster Upgrade from 10.0 to 10.1

MariaDB 10.1 is Galera ready by default. This is not so much of a database issue but more of an installation issue:

Since MariaDB 10.1, the MySQL-wsrep patch has been merged into MariaDB Server. Therefore, in MariaDB 10.1 and above, the functionality of MariaDB Galera Cluster can be obtained by installing the standard MariaDB Server packages and the Galera wsrep provider library package. [ 3 ]

MariaDB Galera Cluster Upgrade from 10.1 to 10.2 and 10.2 to 10.3

Here we have no huge changes so we do not expect any significant problems.

MariaDB Galera Cluster Upgrade from 10.3 to 10.4

In MariaDB 10.4 we have the new Galera version 4 plug-in with the new streaming replication functionality. An upgrade is possible from newest MariaDB 10.3 to MariaDB 10.4 as follows:

If you are upgrading from the most recent MariaDB 10.3 release to MariaDB 10.4, then the versions will be compatible. MariaDB 10.3 uses Galera 3, and MariaDB 10.4 uses Galera 4. This means that upgrading to MariaDB 10.4 also upgrades the system to Galera 4. However, Galera 3 and Galera 4 should be compatible for the purposes of a rolling upgrade, as long as you are at least MariaDB 10.4.4 or later. [ 6 ]

MariaDB Galera Cluster Upgrade from 10.4 to 10.5

Here again we have no huge changes so we do not expect any significant problems.

Skipping MariaDB Major Release Series

About skipping Major Releases MariaDB documentation states:

You should be able to trivially upgrade from ANY earlier MariaDB version to the latest one (for example MariaDB 5.5.x to MariaDB 10.5.x), usually in a few seconds. [ 9 ]