does resizing a vm's disk delete the old disk?

Question

i'm troubleshooting some unattached premium disks i found in a resource group containing a functioning vm and its attached disks

prior to this i know of 2 actions that might have triggered this

• during the arm template debug cycle extra disks may have been created
• during the performance testing the vm disk was resized from the portal a few times

i'm wondering what the expected behaviour is for the latter action, resize vm disk from the portal

the question is, does/should resizing the vm disk from the portal leave the old disk orphaned or is it deleted?

Answer 1

Hello @ataxlab canary ,
When you resize the OS VM disk it will just replace the original disk.

1. For example , lets say right now you have a VM1 with OS disk name disk1 with 127 GB
   When you try to resize the OS disk1 to 256 GB , it will just replace the original one.
   2. If you just delete the VM , then OS disk will be retained .

(FYI - OS disk can be resized only when the underlying VM is in stopped state)

Let us know if you have additional questions.

(If the above clarifies your query , kindly upvote and accept the answer )