Monitoring MariaDB read replicas - Amazon Relational Database Service

Monitoring MariaDB read replicas

For MariaDB read replicas, you can monitor replication lag in Amazon CloudWatch by viewing the Amazon RDS ReplicaLag metric. The ReplicaLag metric reports the value of the Seconds_Behind_Master field of the SHOW REPLICA STATUS command.

Note

Previous versions of MariaDB used SHOW SLAVE STATUS instead of SHOW REPLICA STATUS. If you are using a MariaDB version before 10.5, then use SHOW SLAVE STATUS.

Common causes for replication lag for MariaDB are the following:

  • A network outage.

  • Writing to tables with indexes on a read replica. If the read_only parameter is not set to 0 on the read replica, it can break replication.

  • Using a nontransactional storage engine such as MyISAM. Replication is only supported for the InnoDB storage engine on MariaDB.

When the ReplicaLag metric reaches 0, the replica has caught up to the source DB instance. If the ReplicaLag metric returns -1, then replication is currently not active. ReplicaLag = -1 is equivalent to Seconds_Behind_Master = NULL.