The Amazon RDS Read Replica feature lets you create a DB Instance as a
replica of another DB Instance. Any updates to the data on the source DB Instance
are replicated to the Read Replica DB Instances using the built-in replication
feature of MySQL 5.1. You can use the Read Replica feature to scale beyond the capacity
constraints of a single DB Instance for read-heavy database workloads.
For more information on the Amazon RDS Read Replica feature, go to the Amazon Relational Database Service User Guide.