Introduction

MMM (MySQL Master-Master Replication Manager) is set of flexible scripts to perform monitoring and management of MySQL Masrter-Master replication cluster configurations.

Details

Generally, MMM offers MySQL monitoring and automatic failover for master-master pairs, it also has scripts for data backups, resynchronization between nodes etc.

In two node master-master setup, MMM uses five IPs: single permanent IP for each node that is never changed, 2 reader IPs (read-only) and 1 writer IP (updates). Last three IPs are migrating between the nodes depending on node availability.

Normally (no replication failures, no replication delay etc) active master has 2 IPs (reader and writer), standby master - 1 IP (reader). In case of a failure, both - writer and reader roles migrate to the working node.