Galera Cluster
A synchronous multi-master replication library for MySQL, MariaDB, and Percona Server — every node accepts reads and writes, with no replication lag and no lost transactions on failover.
Galera Cluster, developed by Codership, replicates transactions synchronously across every node via certification-based replication: a transaction only commits once every node has validated (“certified”) it against conflicting writes in-flight elsewhere in the cluster, which removes the replication lag and lost-transaction windows inherent to traditional asynchronous MySQL replication. Any node accepts both reads and writes, cluster membership is managed automatically, and a failed node is simply dropped from the cluster rather than triggering a manual failover.
It’s released under the GPLv2 license and ships as a loadable wsrep provider plugin rather than a standalone server. Galera is the clustering engine underneath both MariaDB Galera Cluster and Percona XtraDB Cluster, and can also be built directly against upstream MySQL via the companion codership/mysql-wsrep repository.
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