AWS RDS PIOPS bottlenecked

Question

I have the following instances and my write PIOPS is bottlenecked at 20% of the allocated PIOPS.

db.r3.xlarge
Provisioned IOPS (SSD)
5000 PIOPS
600 GB

Does anyone have any idea why it's stuck there?

Answer 1

IOPS and throughput are the two factors that limit your  RDS instance type I/O. It's your throughput that gets stuck when your IOPS limit is not reached.
Upgrade from r3.xlarge to r3.2xlarge so that you can test your throughput needs and update accordingly.