MariaDB Galera Cluster: Setting Up a 3-Node High-Availability Cluster

What is Galera Cluster

MariaDB Galera Cluster is a synchronous multi-master replication solution. All three nodes accept writes simultaneously. If one node fails, the cluster continues working. Ideal for high-availability applications.

Galera Configuration (each node)

[mysqld]
binlog_format=ROW
wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so
wsrep_cluster_name="my_cluster"
wsrep_cluster_address="gcomm://10.0.0.1,10.0.0.2,10.0.0.3"
wsrep_node_address="10.0.0.1"  # unique per node
wsrep_node_name="node1"         # unique per node
wsrep_sst_method=rsync

Bootstrap Cluster (node1 only)

sudo galera_new_cluster

Start Remaining Nodes

sudo systemctl start mariadb

Check Cluster Status

mysql -u root -p -e "SHOW STATUS LIKE 'wsrep_%';" | grep -E "cluster_size|cluster_status|ready"