Added limitation if the disk is attached to a VM

[mhenderik]

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[ttorble]

@roygara

Can you review the proposed changes?

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[roygara]

@mhenderik Hi there. I went ahead and confirmed with the product team that this isn't a restriction and that the feature doesn't behave this way. Can I ask why you were adding this to the documentation? Did you encounter a scenario where it was occurring? :)

[mhenderik]

Certainly, there are 2 reasons why I request this document change.

First of all I changed a P80 tier to a P60 tier today using terraform. The VM went down and got deallocated. After the tier was changed the VM got booted again.

Secondly, although I searched and searched the Microsoft documentation, it is mentioned in the terraform documentation in de notes section.

https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/managed_disk#tier-1

I'm glad you picked this request up this quickly. Thanks for this.

[roygara]

@mhenderik Interesting. Thanks for the clarification. :)

The product team had already tested and this behavior wasn't exhibited if the change is made in the Azure portal. I've circled back with them and mentioned you saw this with terraform, and that terraform is documenting it. We'll see what the product team comes back with.

[mhenderik]

@roygara it is kinda weird if only terraform had this "issue". In the end it are just some api calls. The sad thing is, I checked the documentation and I was certain no harm was done. Well one of the production VMs went down. Luckily just a database replica but still.

Currently I'm in the 12 hour cooldown period of upgrading a few disks on a test vm. Tomorrow I'll try to downgrade them via the portal. But then, what kind of magic is happening behind the scenes. I wonder... 😄

Thanks for all the feedback!

[mhenderik]

Finally I was able to test it myself. Indeed via the Azure portal it does work without deallocation the VM. In that case the comment might me more appropriate to switch to:

" - Changing the tier of a managed disk with IaC tools like Terraform may require deallocating the associated VM during the update process."

However I do wonder what the team will say since I expect that both operations are using the same API's.