How to change RDS instance type in Aurora cluster without downtime?

Question

I want to change the instance type of the current Reader (PostgreSQL),
and I am having 2 Reader instances.
I will replace the instance one by one, wait for it to succeed, then replace the next instance.
Will this cause downtime for my Aurora Cluster, and if yes, how long will it be?

Accepted Answer

Hello,

The following link include information for your use case

> **Amazon RDS Multi-AZ with two readable standbys:** Automatically failover in typically under 35 seconds with zero data loss and with no manual intervention.

https://aws.amazon.com/rds/features/multi-az/#Amazon_RDS_Multi-AZ_with_two_readable_standbys

Answer

There is no way to change instance class of Aurora instances. It may take up to 15 mins. From this [link ](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.Managing.html#AuroraPostgreSQL.Managing.Performance.InstanceScaling): 
"Scaling isn't instantaneous. It can take 15 minutes or more to complete the change to a different DB instance class. We recommend that if use this approach to modify the DB instance class, you apply the change during the next scheduled maintenance window (rather than immediately) to avoid affecting users. "

How to change RDS instance type in Aurora cluster without downtime?

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