Configuring MariaDB Galera Cluster

A number of options need to be set in order for Galera Cluster to work when using MariaDB. These should be set in the MariaDB option file.

Mandatory Options

Several options are mandatory, which means that they *must* be set in order for Galera Cluster to be enabled or to work properly with MariaDB. The mandatory options are:

• wsrep_provider — Path to the Galera library
• wsrep_cluster_address — See Galera Cluster address format and usage
• binlog_format=ROW — See Binary Log Formats
• default_storage_engine=InnoDB
• innodb_autoinc_lock_mode=2
• innodb_doublewrite=1 — This is the default value, but it should not be changed when using Galera provider version >= 2.0.
• query_cache_size=0 — Only mandatory for MariaDB versions prior to MariaDB Galera Cluster 5.5.40, MariaDB Galera Cluster 10.0.14, and MariaDB 10.1.2.
• wsrep_on=ON — Enable wsrep replication (starting 10.1.1)

Performance-related Options

These are optional optimizations that can be made to improve performance.

• innodb_flush_log_at_trx_commit=0 — This is not usually recommended in the case of standard MariaDB. However, it is a bit safer with Galera Cluster, since inconsistencies can always be fixed by recovering from another node.

Replication Filters

When using Galera Cluster, replication filters should be used with caution because they may not work as you'd expect.

The following replication filters are honored for InnoDB DML, but not DDL:

• binlog_do_db
• binlog_ignore_db
• replicate_wild_do_table
• replicate_wild_ignore_table

The following replication filters are honored for InnoDB DML and DDL:

• replicate_do_table
• replicate_ignore_table

However, it should be kept in mind that if replication filters cause inconsistencies that lead to replication errors, then nodes may abort.