Restarting the cluster nodes¶
To restart a cluster node, shut down MySQL and restarting it. The node should leave the cluster (and the total vote count for quorum should decrement).
When it rejoins, the node should synchronize using IST.
If the set of changes needed for IST are not found in the
on any other node in the entire cluster,
then SST will be performed instead.
Therefore, restarting cluster nodes for rolling configuration changes
or software upgrades is rather simple from the cluster’s perspective.
If you restart a node with an invalid configuration change that prevents MySQL from loading, Galera will drop the node’s state and force an SST for that node.
If MySQL fails for any reason, it will not remove its PID file (which is by design deleted only on clean shutdown). Obviously server will not restart if existing PID file is present. So in case of encountered MySQL failure for any reason with the relevant records in log, PID file should be removed manually.