Why is my Amazon RDS DB instance in storage-optimization state for a long time?
Last updated: 2022-07-06
I updated the storage size of my Amazon Relational Database (Amazon RDS) DB instance. However, the process is taking a long time, and the instance is in 'storage-optimization' state.
When you modify the storage size of your Amazon RDS DB instance, the status of the instance changes to storage optimization. This means that your DB instance is being modified to change the storage size or type. The storage optimization process is performed by RDS automation to make sure that data is evenly distributed to the underlying Amazon Elastic Block Store (Amazon EBS) volumes after storage modification.
Scaling storage in most cases doesn't cause any outage or performance degradation of the DB instance though this operation might take several hours. You can't make further storage modifications for either six hours or until storage optimization has completed on the instance, whichever is longer. However, when the DB instance is in the storage-optimization status, the instance is operational. Your application availability isn't affected. You don't have to wait for the DB instance to be in Available state to run your applications.
Note that any type of storage modification might result in the DB instance moving to storage optimization status. However, modifying the storage might also cause the instance to restart, requiring some downtime. This is needed in specific cases, such as changing the storage type from SSD to magnetic or vice versa. For more information, see Settings for DB instances.
To monitor the amount of free storage for your DB instance and action when necessary, it's a best practice to create an Amazon CloudWatch alarm.