The Multi-Master Monitor is a monitoring module for MaxScale that monitors Master-Master replication. It assigns master and slave roles inside MaxScale based on whether the read_only parameter on a server is set to off or on.
A minimal configuration for a monitor requires a set of servers for monitoring and an username and a password to connect to these servers. The user requires the REPLICATION CLIENT privilege to successfully monitor the state of the servers.
[Multi-Master Monitor] type=monitor module=mmmon servers=server1,server2,server3 user=myuser passwd=mypwd
Common Monitor Parameters
For a list of optional parameters that all monitors support, read the Monitor Common document.
Multi-Master Monitor optional parameters
These are optional parameters specific to the Multi-Master Monitor.
Allow previous master to be available even in case of stopped or misconfigured replication. This allows services that depend on master and slave roles to continue functioning as long as the master server is available.
This is a situation which can happen if all slave servers are unreachable or the replication breaks for some reason.