MariaDB Replication Setup

Deterministic patterns for primary-replica replication: async baseline, semi-sync, parallel applier, GTID, and multi-source named connections. Skill covers MariaDB 10.6-LTS, 10.11-LTS, 11.x, 12.x.

Quick Reference

• ALWAYS set a UNIQUE server_id (1 to 2^32-1) on every node before enabling log_bin. Two nodes with the same server_id silently corrupt replication.
• ALWAYS use binlog_format=MIXED (default since 10.2.4) or ROW. NEVER use STATEMENT alone with non-deterministic functions (UUID(), NOW(6), LIMIT without ORDER BY, SLEEP, user-defined functions).
• Semi-sync is BUILT-IN from MariaDB 10.3+. NEVER run INSTALL PLUGIN rpl_semi_sync_master. Just set rpl_semi_sync_master_enabled=ON on the primary and rpl_semi_sync_slave_enabled=ON on the replica.
• On rpl_semi_sync_master_timeout (default 10000 ms) the primary falls back to async and logs a warning. When a replica catches up, semi-sync resumes automatically. Apparent "hangs" under load are usually this timeout being too low.
• slave_parallel_mode=optimistic is the DEFAULT from 10.5.1+. Earlier versions default to conservative. Both primary and replica must be 10.0.5+ for any parallel mode.
• Start slave_parallel_threads at 4-8 and TUNE based on actual disk-IO benchmark on the replica. NEVER set above 16 without proof it helps.
• MariaDB GTID format is domain-server-sequence (e.g. 0-1-1234). MySQL GTID is uuid:seqno. They are INCOMPATIBLE. MariaDB can replicate FROM a MySQL primary, but MySQL CANNOT replicate from a MariaDB primary. For two-way or MariaDB-to-MySQL: dump-and-load, not GTID.
• Multi-source uses NAMED CONNECTIONS: CHANGE MASTER 'channel_name' TO .... NEVER use MySQL FOR CHANNEL syntax: it returns a syntax error.
• SHOW SLAVE STATUS (single source) or SHOW ALL SLAVES STATUS (multi-source, 10.0+). Replica aliases SHOW REPLICA STATUS exist from 10.5+. Both Slave_IO_Running and Slave_SQL_Running MUST be Yes.
• Replication user privileges: REPLICATION SLAVE (mandatory) + REPLICATION CLIENT (recommended, for SHOW MASTER STATUS).

Decision Tree : Which Replication Shape