AWS Aurora MySQL Manual Failover Instructions – Demote Writer instance to Reader instance

This article is for you if…

  • You are using Aurora MySQL on Amazon Web Services (AWS).
  • You have one Writer instance and one Reader instance.
  • You would like to perform a manual failover (so that your Writer instance is demoted to a Reader instance).

I needed to do this recently, but could not find clear instructions anywhere. Here are step-by-step instructions with screenshots.

  1. Login to your AWS Console
  2. Go to the RDS Console and select your Aurora MySQL Cluster
  3. Highlight your Aurora MySQL Writer Instance, choose Failover from the Actions menu

    Comment: Highlighting a specific instance may not be important. I believe if you have multiple Reader instances, the failover will use the “Failover priority” (e.g. “tier-0”, “tier-1”, … “tier-15”) to determine which Reader to promote to Writer. When I added a temporary 2nd Reader with “Failover priority” of “tier-0” and performed failover, that Reader was promoted to Writer. Please post a comment at the bottom of this page if you can confirm how failover is handled with multiple Reader instances! If the “Failover priority” is used to select which Writer instance will be promoted, please confirm if “tier-0” is indeed considered first when promoting a Reader to a Writer and I will update these instructions.

4. Confirm you would like to failover the cluster.

5. Go to the RDS Console and select your Aurora MySQL Cluster. The page will not show any changes for a few seconds.

6. Go to the RDS Console and select your Aurora MySQL Cluster (or refresh the page). Repeat until the page shows that the Writer instance has been demoted to a Reader instance.

7. Failover complete!

In my experience, the failover occurs within 10-15 seconds after submitting the failover request. Our application is aware of the separate reader and writer instances. We have not noticed any application read errors during the manual failover process. However, we have noticed temporary write errors during the failover process. Our application is designed to handle brief write failures and retry the writes, so this was not an issue.

Did you find this helpful? Let me know by sending me a comment. I tend to update and maintain posts more frequently if I know others find them helpful. Thanks for visiting!

Leave a Reply

Your email address will not be published. Required fields are marked *