CODEWITHSUNDEEP
amazon-rdsaws-serverlessaws-aurora-serverless
Ben Walton
Ben Walton

Reputation: 453

Aws Aurora serverless v2 will not scale down to .5 ACU even though 0 connections

I'm running a v2 instance and from the documentation aws states you should only be paying for resources that you are actually using. I have an instance than is most of the time at 0 connections but it never scales down under 2 ACUs. See images below for reference. I have the instance setup to scale between 0.5-16ACU. But it doesn't seem to matter the load it always stays at a baseline of 2ACUs.

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Upvotes: 10

Views: 5088

Answers (5)

tbmpls
tbmpls

Reputation: 231

I had the same situation. Our cluster would not scale down to 0.5 ACU even though there were no connections and no activity (test environment). This sequence fixed it for me:

  • Modify the Cluster to turn off 'Enable Performance Insights'. Wait for cluster to implement the change.
  • On the Cluster, Actions / 'Stop Temporarily'. This took at least several minutes to shut down.
  • Restart the Cluster.
  • Modify the Cluster to turn back on 'Enable Performance Insights'

The Cluster has been at 0.5 ACUs for a couple of days now as it should be.

I suspect that modifying the cluster to Turn off/on Enable Performance Insights wasn't needed but of course I can't go back to re-try that now.

Before doing this I had also reached out to AWS Tech Support. They had suggested that Enhanced Monitoring and Performance Insights could be leading to the issue but I have this setup in a different environment and it scales down to 0.5 ACU as expected. But the clue they gave me was to stop the database. I had previously rebooted the writer instance which did not fix the problem. It was the cluster that needs to be shut down and restarted.

Upvotes: 0

stephane.c
stephane.c

Reputation: 186

be aware also if you use a serverless as a backup failover in a cluster with a provisioned production server (a common scenario where you want the serverless to be at 0.5 ACU).

If your serverless is Tier1 (the default), AWS will automatically provision the same number of ACU as the writer instance (so if you have for example a r6x2large production writer (64Gb), the serverless will stay at 128 ACU even if there's zero connection).

So make sure to set it to Tier2 or higher.

Upvotes: 0

ajain
ajain

Reputation: 344

I had a similar issue and was coming back to this page again and again only to find no new answers have been added. Finally I decided to contact AWS support for it and the solution was very simple. AWS had some underlying patch added for it, which was supposed to be upgraded manually. Once the upgrade is made to all the instances in the cluster, the ACUs have come down. Now, I am planning to reduce the minimum ACU even lower to see if it can go further down (I had it set to 2 as minimum but my cluster was stuck at 4 ACUs).

Upvotes: 0

Ben Walton
Ben Walton

Reputation: 453

I had to turn off the AI monitoring on the DB. Then restart the instance. This then started the db at the minimum.

Upvotes: 2

graemebryce
graemebryce

Reputation: 1

I can confirm this behaviour but as yet can't explain it. We have three databases running, all with the same schema and with different ACU limits set. Our production and staging databases insist at near flatlines close to the max capacity allowed whilst one other behaves as we would expect and only shows an upscale when we actually send it load.

We have tried rebooting the instances but they immediately scale up and do not appear willing to scale down.

We have full support with AWS so will raise a ticket with them and should report back here if we get an explanation/solution

Upvotes: 0

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