active-active

For this how-to we were working with a MariaDB 10.6.5 database server and the newest MariaDB MaxScale 6.3.0 (aka 2.6) load balancer/proxy.

As a starting point we had a working MariaDB Master/Master replication with one active Master (M_a) and one passive Master (M_p). Whereas the passive Master was set to read_only. As a replication user we used the user replication.

Electing a slave as new master and aligning the other slaves to the new master

In a simple MySQL Replication set-up you have high-availability (HA) on the read side (r). But for the master which covers all the writes (w) and the time critical read (rt) there is no HA implemented. For some situations this can be OK. For example if you have rarely writes or if you can wait until a new Master is set up.

But in other cases you need a fast failover to a new master.