Set the desired level of IOPS with Amazon RDS
Amazon's Cloud computing now includes new high performance provisioned IOPS storage for its Relational Database Service. Now, you can provision new RDS database instances with 1,000 to 10,000 IOPS, and with 100GB to 1 TB of storage for MySQL and Oracle databases. If you are using SQL Server, the maximum IOPS you can provision is 7,000 IOPS. The creation of an RDS instance with specified level of IOPs should give you more consistent throughput and performance.
Read more here - http://aws.typepad.com/aws/2012/09/new-high-performance-provisioned-iops-amazon-rds.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+AmazonWebServicesBlog+%28Amazon+Web+Services+Blog%29