iops
The amount of Provisioned IOPS (input/output operations per second) to be initially allocated for each DB instance in the Multi-AZ DB cluster.
For information about valid IOPS values, see Amazon RDS Provisioned IOPS storage in the Amazon RDS User Guide.
Valid for Cluster Type: Multi-AZ DB clusters only
Constraints:
Must be a multiple between .5 and 50 of the storage amount for the DB cluster.