Reducing Allocated Storage for RDS Instance to Optimize Costs(Caused by Storage Autoscaling)

Question

I have an Amazon RDS instance with an allocated storage of 3000GB, but the actual storage usage is only around 1300GB. This means I'm paying for 1700GB of storage that I'm not utilizing, incurring unnecessary costs. I would like to reduce the allocated storage to approximately 1500GB to optimize my costs and align the allocated storage with my actual usage.

Here are the details:

RDS Instance Type: PostgreSQL
Allocated Storage: 3000GB
FreeStorageSpace: 2200GB
Meaning Storage Used: 1300GB

I have created a new instance from a snapshot to reduce this but the minimum allocated storage is still set to the 3000GB which means I can't go below the 3000GB.

I would appreciate guidance on the best approach to reduce the allocated storage for my RDS instance to around 1500GB. If there is a way to modify the allocated storage without creating a new instance, that would be ideal.

However, if creating a new instance is necessary, please provide step-by-step instructions on how to migrate the data safely without any data loss or downtime.

I'm looking for a cost-effective solution that aligns my allocated storage with my actual usage while minimizing any potential risks or downtime.

Thank you in advance for your help!

Accepted Answer

Unfortunately you can't decrease the allocated size after the instance is created. Please refer to this article on [how to decrease the total provisioned storage size.](https://repost.aws/knowledge-center/rds-db-storage-size)

Answer

When restoring an Amazon RDS instance from a snapshot, the minimum allocated storage size for the new instance is determined by the maximum storage size ever used by the original instance. If the original instance's storage was increased to 3000GB at any point, the new instance cannot be restored with a smaller storage size, even if the current usage is only around 1300GB. Check here for more information [Restoring from a snapshot](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_RestoreFromSnapshot.html).

#### Possible Solution:
To work around this limitation, export the data from the original instance and import it into a new instance with the desired storage size of 1500GB. This process involves creating a new RDS instance with the desired storage size, using a database export tool to export the data from the old instance, and then importing the data into the new instance. Once the data transfer is complete and the new instance is functioning correctly, the old instance can be deleted.

Reducing Allocated Storage for RDS Instance to Optimize Costs(Caused by Storage Autoscaling)

Possible Solution:

Relevant content