When should I choose Provisioned IOPS over Standard RDS storage?
If you have batch-oriented workloads
If you use production online transaction processing (OLTP) workloads
If you have workloads that are not sensitive to consistent performance
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_Storage.html Amazon RDS provisions that
IOPS rate and storage for the lifetime of the DB instance or until you change it. Provisioned IOPS storage is
optimized for I/O intensive, online transaction processing (OLTP) workloads that have consistent performance
requirements. Provisioned IOPS helps performance tuning.