Explanation
Why the waste happens and who it affects.
In many cases, provisioned IOPS are set at or below the free baseline included with gp3 (3,000 IOPS and 125 MiB/s, rising to 12,000 IOPS and 500 MiB/s for volumes of 400 GiB or more on Db2, MariaDB, MySQL, and PostgreSQL, or 200 GiB or more on Oracle; RDS for SQL Server stays at 3,000 IOPS and 125 MiB/s). In such scenarios, continuing to use provisioned IOPS storage results in elevated cost with no functional advantage. These misconfigurations often persist due to legacy templates, default settings, or a lack of periodic review.
Billing model
The pricing dimensions that drive this cost.
RDS storage is billed per GB-month based on the storage type selected. Premium options like io1 and io2 charge separately for provisioned IOPS, while general-purpose types like gp3 include baseline IOPS and throughput at no extra cost. Overprovisioning or selecting the wrong storage tier leads to unnecessary spend.
How to detect
4 checks to find it in your estate.
- Identify RDS instances using high-cost storage types (e.g., io1, io2)
- Review IOPS and throughput metrics to assess whether provisioned performance is being fully utilized
- Evaluate whether current workloads would meet SLAs with a general-purpose alternative like gp3
- Confirm with application owners whether the selected storage type is still required
How to fix
How to remove the waste.
If the provisioned IOPS are within the gp3 baseline, migrate to gp3 to reduce costs without impacting performance. Storage type can be changed by modifying the DB instance, either immediately or during the next maintenance window; in most cases this requires no outage, although the instance enters a storage-optimization state with somewhat elevated latency until the change completes. Update infrastructure templates and provisioning logic to default to gp3 when appropriate.
Documentation
Vendor references for pricing and configuration.