diff --git a/Documentation/Monitors/MariaDB-Monitor.md b/Documentation/Monitors/MariaDB-Monitor.md index 8ca3e45cb..b6d2924c3 100644 --- a/Documentation/Monitors/MariaDB-Monitor.md +++ b/Documentation/Monitors/MariaDB-Monitor.md @@ -246,14 +246,16 @@ In addition, the monitor needs to know which username and password a slave should use when starting replication. These are given in `replication_user` and `replication_password`. -All three operations can be activated manually through MaxAdmin. Failover -selects the new master server automatically, switchover and rejoin require the -user to designate the new master. Switchover also requires the user to designate -the current master server which will be replaced by the new. Example commands -are below: +All three operations can be activated manually through MaxAdmin/MaxCtrl. All +commands require the monitor instance name as first parameter. Failover selects +the new master server automatically and does not require additional parameters. +Switchover requires the new master server name. Additionally, the user may +designate the current master server in the switchover command. Rejoin requires +the name of the joining server. Example commands are below: ``` call command mariadbmon failover MyMonitor +call command mariadbmon switchover MyMonitor SlaveServ3 call command mariadbmon switchover MyMonitor SlaveServ3 MasterServ call command mariadbmon rejoin MyMonitor NewServer2 ``` @@ -285,7 +287,7 @@ With `auto_rejoin` active, the monitor will try to rejoin any server matching the above requirements. When activating rejoin manually, the user-designated server must fulfill the same requirements. -### Limitations +### Limitations and requirements Switchover and failover only understand simple topologies. They will not work if the cluster has multiple masters, relay masters, or if the topology is circular. @@ -309,6 +311,13 @@ any users who commonly do updates should not have the SUPER-privilege. For even more security, the only SUPER-user session during a switchover should be the MaxScale monitor user. +When mixing rejoin with failover/switchover, the backends should have +*log_slave_updates* on. The rejoining server is likely lagging behind the rest +of the cluster. If the current cluster master does not have binary logs from the +moment the rejoining server lost connection, the rejoining server cannot +continue replication. This is an issue if the master has changed and +the new master does not have *log_slave_updates* on. + ### Configuration parameters #### `auto_failover`