How can I convert my On-demand RDS DB Instance to Reserved RDS DB Instance?

Question

Hi,
I am running On-demand Sql Server RDS DB Instance for last 5 Years. Now I want to opt in for reserved RDS db instance. Is there a way I can just convert my existing on-demand DB instance to a Reserved Db instance?

I already explored the "Purchase Reserved DB Instance" option. There it seems I would end up buying another reserved instance and then I would need to migrate my data from my existing instance to the new reserved instance. This would be very challenging and error prone activity for me.

Instead, it would better for me to convert the existing DB instance to reserved db instance.
My objective is to avoid data migration challenges and to prevent other connectivity factors to change because it would demand me to update all connection strings in my applications.

secondabhi_aws · Answer

Hi,

Reserved instances are just a billing constructs, wherever they're available for services such as RDS, EC2, ElastiCache, etc. You need not to make any change to existing RDS instance. It's just, you purchased an RI and now it(discount) would immediately be applied to your instances of that type.

No changes are required for the instance, if you have an instance of m4.large instance in us-east-2a, one of your m4.large instances in us-east-2a will immediately begin charging at the lower hourly rate(RI's rate).

Please take a look at **"How Billing Works"** section on [Amazon RDS Reserved Instances](https://aws.amazon.com/rds/reserved-instances/).

For your quicker reference, attaching snapshot, where it clearly says, RIs discount automatically applies to already running instances of that type:

![Enter image description here](/media/postImages/original/IMDwIAhL_wQZ2XRJNdre1jkw)

**Conclusion:** You need not to convert On-demand RDS DB Instance to Reserved RDS DB Instance(it doesn't work that way), as once you purchase RI's plan of that instance type, discount would start getting applied immediately.

**References:** [Reserved DB instances for Amazon RDS Documentation](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithReservedDBInstances.html#USER_WorkingWithReservedDBInstances.Purchasing)

Feel free to comment if you have any additional questions.

How can I convert my On-demand RDS DB Instance to Reserved RDS DB Instance?

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