Currently, RDS for MySQL 5.6 and 5.7 support read replicas.
If few write requests but many read requests must be sent to the database, a single DB instance may be unable to handle the read pressure. In this case, operations may be affected. To expand the DB instance read ability to offload read pressure on the database, you can create one or more read replicas in a region. These read replicas can process a large number of read requests and increase application throughput.
A read replica uses the architecture of a single physical node (without a slave node). Changes to the primary DB instance are also automatically synchronized to all associated read replicas through the native replication function of MySQL. The synchronization is not affected by network latency. Read replicas and the primary DB instance must be in the same region but can be in different AZs.
RDS provides up to 20 monitoring metrics, including storage space, IOPS, number of database connections, CPU usage, and network traffic. You can view these metrics to determine the load of DB instances.