Upgrading from MariaDB 10.4 to MariaDB 10.5 Galera Cluster

Sat, 2020-11-21 20:58 — Shinguz

Because upgrading from MariaDB 10.4 to MariaDB 10.5 (non-clustered) seems not to be a problem [ 1 ] we take the challenge and try to create a receipt based on the MariaDB 10.3 to MariaDB 10.4 Galera Cluster upgrade documentation [ 3 ]:

Before you start

Before you begin with the upgrade you should consider a few things:

Downgrade is officially not supported! [ 4 ] It might work, or not.
So you should have taken a proper an clean backup before you start with the upgrade and you should be sure the restore works as well!
It is recommended to upgrade to the newest MariaDB minor release first [ 5 ] before you upgrade to a new major release. This reduces the risk that you run into already known and fixed bugs.
Take a look at Upgrading from MariaDB 10.4 to MariaDB 10.5 [ 1 ] to see what has changed between the major versions.
New MariaDB Major Release may behave differently than older MariaDB Major Release. Thus you should test the new major release series first before putting it into production!
Ideally, you want to have a large enough Galera Cache to avoid a State Snapshot Transfer (SST) during the rolling upgrade. The Galera Cache size can be configured by setting the Galera variable gcache.size.
For example: wsrep_provider_options = "gcache.size=2G"

Performing a Rolling Upgrade

The following steps can be used to perform a rolling upgrade from MariaDB 10.4 to MariaDB 10.5 when using Galera Cluster. In a rolling upgrade, each node is upgraded individually, so the cluster is always operational. There is no downtime from the application's perspective.

For each node, perform the following steps:

Modify the repository configuration, so the system's package manager installs MariaDB 10.5.
If you use a load balancer such as MaxScale, ProxySQL or HAProxy, make sure to drain the node from the pool so it does not receive any new connections.
Stop the MariaDB node.
Uninstall the old version of MariaDB and the Galera wsrep provider library.
Install the new version of MariaDB and the Galera wsrep provider library.
Make any desired changes to configuration options in option files, such as my.cnf. This includes removing any system variables or options that are no longer supported.
On Linux distributions that use systemd you may need to increase the service start-up timeout as the default timeout of 90 seconds may not be sufficient.
Start the MariaDB node.
Run mariadb-upgrade with the --skip-write-binlog option (I personally think this option is not necessary because it is the default).
mariadb-upgrade does two things:
- 1. Ensures that the system tables in the mysql database are fully compatible with the new version.
- 2. Does a very quick check of all tables and marks them as compatible with the new version of MariaDB.

When this process is done for one node, move onto the next node.

Note: When upgrading the Galera wsrep provider library, sometimes the Galera protocol version can change. The Galera wsrep provider should not start using the new protocol version until all cluster nodes have been upgraded to the new version, so this is not generally an issue during a rolling upgrade.
However, this can cause issues if you restart a non-upgraded node in a cluster where the rest of the nodes have been upgraded already.