Amazon RDS for MySQL now supports up to 15 read replicas for RDS Multi-AZ deployment option with two readable standby database instances

Amazon RDS now allows the creation of 15 additional asynchronous read replicas outside the cluster in addition to the two readable standby instances in Multi-AZ deployments with two readable standbys.

This enables scaling up the read capacity to 17 instances, providing improved performance and durability for read-heavy database workloads. The read replicas can also be promoted and modified to be a Multi-AZ deployment option with two readable standbys when needed.

Furthermore, Multi-AZ deployments with two readable standby database instances have faster transaction commit latencies compared to Multi-AZ deployments with one standby instance, and automated failovers typically take under 35 seconds. The two readable standbys can also serve read traffic.