MariaDB Galera Cluster

MariaDB Galera Cluster is a synchronous multi-master replication solution for MariaDB. It is built on the Galera replication library, originally developed by Codership (acquired by MariaDB in 2025). Unlike traditional MySQL replication, which is asynchronous and uses a single primary, Galera keeps all nodes in sync — every node accepts reads and writes, and transactions are certified across the cluster before committing.

The cluster uses the wsrep (write set replication) API to intercept commits at the database level and replicate them as write sets to all other nodes. Certification-based conflict detection ensures that conflicting transactions on different nodes are resolved deterministically. When a node joins or rejoins the cluster, Galera handles state transfer automatically — either incrementally from the transaction log or as a full snapshot. This makes adding capacity or recovering from failures straightforward.

The Galera documentation covers cluster setup, configuration, and monitoring. MariaDB also maintains integration guides specific to MariaDB Server.