Why is my Amazon RDS DB instance in the storage-optimization state for a long time?

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I updated the storage size of my Amazon Relational Database (Amazon RDS) DB instance. But, the process is taking a long time, and the instance is in the storage-optimization state.

Resolution

When you modify the storage size of your Amazon RDS DB instance, the status of the instance changes to storage optimization. This modifies your DB instance to change the storage size or type. The storage optimization process is performed by RDS automation. RDS automation confirms that the data is evenly distributed to the Amazon Elastic Block Store (Amazon EBS) volumes after storage modification.

In most cases, scaling storage doesn't cause an outage or performance degradation of the DB instance. However, this operation might take several hours. You can't make further storage modifications for either 6 hours or until storage optimization completes on the instance, whichever is longer. But, you can perform any other instance modifications, such as instance size scaling or rebooting.

Typically, the storage optimization completes in a few hours, but can sometimes take up to or more than 24 hours. When the DB instance is in the storage-optimization state, the instance is operational. Your application availability isn't affected. You don't have to wait for the DB instance to be in the available state to run your applications.

Note: There's no way to speed up this process. You must wait for the optimization process to complete. The process takes longer for larger storage size increases and storage usage. Because this is an automated process, there's no fixed way to determine how long it takes to complete storage optimization on your RDS DB instance.

For a cluster volume, Amazon Aurora uses a custom storage solution that isn't backed by EBS volumes. Therefore, you don't need to consider storage optimization for Aurora instances. For more information, see Introducing the Aurora storage engine.

Note: Any type of storage modification might result in the DB instance moving to the storage-optimization state. However, modifying the storage might also cause the instance to restart and require downtime. This is a requirement in specific cases, such as changing the storage type between SSD and magnetic. For more information, see Settings for DB instances.

To monitor the amount of free storage for your DB instance, it's a best practice to create an Amazon CloudWatch alarm.

Related information

Managing an Amazon RDS DB instance

AWS OFFICIAL
AWS OFFICIALUpdated 10 months ago
1 Comment

Two things to note:

  1. storage optimization does not necessary occur during maintenance window.
  2. AWS Backup job will fail if the instance state is in storage-optimization state.
Reza
replied 3 months ago