AWS Underutilized RDS Instance

Rule Description

Rule Code: AWS-RDS-03

Identify any Amazon RDS database instances that appear to be underutilized and consider to downsize them.

By default, an RDS database instance is considered "underutilized" when meets both following criteria:

  • The average CPU utilization has been less than 40% for the last 7 days
  • The total number of ReadIOPS and WriteIOPS recorded per day for the last 7 days has been less than 100 on average.

Audit / Verification

Step 01: Log in to the AWS Management Console.

AWS Console login

Step 02: Navigate to RDS dashboard. Choose Instances under RDS Dashboard.

Step 03: Select the RDS instance that you need to check. Navigate the Show Monitoring button to view the graph.

Step 04: Follow the steps as below:

the selected database instance qualifies as candidate for the underused instance. Click X (close) to return to your dashboard.

  • Verify the average CPU utilization has been less than 40% for the last 7 days
  • Verify the total number of Read operations per second for the past 7 days. If the total number of ReadIOPS, WriteIOPS has been less than 100, e.g.

If all conditions outlined at step no. 4 are met, the selected RDS database instance is considered "underutilized" and should be downsized in order to stop accumulating unnecessary usage charges.

Step 05: Repeat steps no. 4 – 6 to verify the CPU, ReadIOPS and WriteIOPS for the rest of the RDS database instances within the current region.

Step 06: Switch to the other AWS regions and follow the same above audit process for other regions.