Galera Cluster is a synchronous multi-master cluster for MySQL that allows you to synchronously replicate your data to every node in the cluster. Galera Cluster makes the life of a DBA easier with features like automatic node joining, electing donor nodes and automatic node removal once a node has failed. There is also no need to distinguish master and slave relations in your application as all nodes in the cluster are writable. Consider all nodes in the cluster as one big MySQL database server.
In this talk I will explain how Spil Games strives to have their entire MySQL environment running on Galera Cluster. At Spil Games we have a large variety of MySQL implementations ranging from traditional functionally sharded database master-master pairs, single masters with many read slaves and user/location sharded database nodes. Migrating these different implementations to a Galera Cluster requires careful planning.
The biggest challenge is to migrate all our existing (ageing) asynchronous Master-Master setup to a synchronous Galera replicator. Because the ageing servers are less performant than the new servers used for Galera we merge multiple existing clusters into one cluster, saving us lots of space and power in our data center.
The session will include design choices, learnings and the pitfalls we fell into.