Multi-AZ instances of MySQL transparently replicate data across AZs using DRBD. Automated backups of multi-AZ instances run off the backup instance to reduce latency spikes on the primary.
🔸Performance Schema: While Performance Schema is enabled by default in MySQL 5.6.6 and later, it is disabled by default in all versions of RDS. If you wish to enable Performance Schema, a reboot of the RDS instance will be required.
🔸MySQL vs MariaDB vs Aurora: If you prefer a MySQL-style database but are starting something new, you probably should consider Aurora and MariaDB as well. Aurora has increased availability and is the next-generation solution. That said, Aurora may not be that much faster than MySQL for certain workloads. MariaDB, the modern community fork of MySQL, likely now has the edge over MySQL for many purposes and is supported by RDS.
RDS MySQL and MariaDB Gotchas and Limitations
🔸No SUPER privileges. RDS provides some stored procedures to perform some tasks that require SUPER privileges such as starting or stopping replication.
🔸There is no ability to manually CHANGE MASTER on replicas, so they must all be rebuilt after a failover of the master.
🔸Most global options are exposed only via DB parameter groups. Some variables that were introduced in later MySQL dot releases such as avoid_temporal_upgrade in MySQL 5.6.24 are not made available in RDS's 5.6.x parameter group and making use of them requires an upgrade to MySQL 5.7.x.
🔸RDS features such as Point-In-Time restore and snapshot restore are not supported on MyISAM tables. Ensure you lock and flush each MyISAM table before executing a snapshot or backup operation to ensure consistency.