The next presentation by Piotr Biel from Percona was on Multi-Master Manager for MySQL.

The introduction included a discussion of the popular MySQL HA solutions including:

• MySQL Master-slave replication with failover
• MMM managed bi-directional replication
• Heartbeat/SAN
• Heartbeat/DRBD
• NDB Cluster

A key problem that was clarified in the talk is the discussion of Multi-Master and this IS NOT master-master. You only write to a single node. With MySQL is this critical because MySQL replication does not manage collision detection.

The MMM Cluster Elements are:

• monitoring node
• database nodes

And the Application Components are:

• mon
• agent
• angel

MMM works with 3 layers.

• Network Layer – uses a virtual IP address, related to servers, not a physical machine
• Database Layer
• Application Layer

MMM uses two roles for management with your application.

• exclusive – also known as the writer
• balanced – also known as the reader

There are 3 different statuses are used to indicate node state

• proper operation
• maintenance
• fatal errors

The mmm_control is the tool used to manage the cluster including:

• move roles
• enable/disable individual nodes
• view cluster status
• configure failover

The Implementation challenges require the use of the following MySQL settings to minimize problems.

• auto_increment_offset/auto_increment_increment
• log_slave_updates
• read_only

FOSDEM 2010 MySQL Developer Room Schedule
FOSDEM 2010 Website
Brussels, Belgium
February 7, 2010