Amazon RDS DB instance stuck in the modifying state may happen when we try to increase the allocated storage for an Amazon RDS DB instance.

Here, at Bobcares, we assist our customers with several AWS queries as part of our AWS Support Services.

Today, let us see how to resolve this error.

Amazon RDS DB instance stuck in the modifying state

By design, storage scaling operations for an Amazon RDS DB instance have minimal impact on ongoing database operations.

In most cases, they completely offload to the Amazon EBS layer and are transparent from the database.

However, when it comes to some legacy Amazon RDS storage volumes, to modify the size, IOPS, or volume type of the Amazon RDS storage we require a different process.

We must use the legacy method under either of the following conditions:

• RDS instance doesn’t have either one or four volumes.
• The target size for the modification increases the allocated storage beyond 400 GB.

Factors that affect the time to increase the allocated storage

1. The legacy method uses I/O resources. This can increase the database workload.

In this case, it is best to use the minimal impact method whenever possible. It doesn’t use any resources on the database.

2. Suppose we have high load conditions and must use the legacy method. Then we can create a read replica for the RDS DB instance.

We can perform the storage scaling operations on the read replica. After that, we can promote the read replica DB instance to the primary DB instance.

3. In case of high-load conditions, our Support Techs recommend the following:

a) First, create a read replica for the RDS DB instance.
b) Then perform storage scaling operations on the read replica.
c) After that, promote the read replica DB instance to the primary DB instance.

Once the storage modification starts, we can’t cancel the operation. The DB instance status will be in modifying state until the Amazon EBS operations are complete.

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Conclusion

In short, we saw how our Support Techs fix the instance stuck error for our customers.