Question on Scaling up App service plan

Question

Hi,

I am currently utilizing an Azure Function App on an App Service Plan placed in the Isolated Tier. I am planning to scale up from the existing Isolated v2 I2V2 to the Isolated v2 I4V2 plan.

My query pertains to whether there will be any downtime encountered during the scale-up process and what scale up stratery is followed?

Answer 1

@Malik, Deepankar, you can't expect there to be zero downtime. When scaling to a different SKU, there will be some cold start costs as the new scale unit needs to start your application.

Answer 2

Hey there Malik, Deepankar

That's a good question and thanks for using QandA platform.

So scaling up your Azure Function App to a higher-tier App Service Plan is a seamless process that typically does not result in any downtime as far as I know.

Azure has various strategies and mechanisms in place t to ensure continuous availability and minimal disruption to your application during the migration.

So yes, I guess there will be minimal to zero downtime will be faced.

If this helps kindly accept the answer thanks much.

Answer 3

Hi,

Yes, there will be small amount of downtime, and some existing sessions/operations may receive an error. To minimize downtime what you can do is create new Isolated V2 I4V2 App Service Plan in same App Service Environment (I assume you are on v3), same operating system, with desired instance count.

Once the new App Service Plan is ready you can navigate to your Function App -- Change App Service plan blade, and switch it to the new plan you created. I suggest switching during off hours. Once you verify everything is running well on the new plan you can delete the old one.

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

Thanks.

-TP