Function app with Elastic Premium service plan won't scale out to 100 instances

Question

I have a function app configured for Elastic Premium plan, that is configured for 100 maximum instances for scale out. as per this documentation, function app on east us should be able to scale to 100 instances, but mine keeps capped at 20 instance with almost 100 % cpu usage. https://learn.microsoft.com/en-us/azure/azure-functions/functions-premium-plan?tabs=portal#region-max-scale-out

I've checked my subscriptions limits&quotas from the portal and couldn't see any limit for this scale operation, how can I identify the issue here, and can you verify with mentioned setup function app indeed needs to be able to scale up to 100 instances.

Note, my app is set to linux os but I've checked this with windows os instance as well and observed the same situation.

Answer 1

Hi Ahmet,

When you create a premium function app via the portal the maximum limit is set to 20 by default.

Please navigate to your function app -- Settings -- Scale out (App Service plan) blade. Please drag the Maximum Burst slider to 100 and click Save. Once that is set, please run your test again to confirm that it scales to 100 instances.

Please click Accept Answer and upvote if the above was helpful.

Thanks.

-TP