SOLVED: Everything You Need To Know About Expanding a Disk on an Azure VM

We are always being asked to expand disk and add new disk to VM’s on Azure and there is some confusion around the process.

how to expand a disk on an Azure VMhow to expand a disk on an Azure VM

Expanding a disk on an Azure virtual machine (WM) is easy:

  1. In the Azure portal, find the server in question
  2. Click / expand SETTINGS
  3. Click SIZE & PERFORMANCE
  4. Select the size of disk you want and click SAVE
  5. Log into the VM
  6. Right click on the START button and select DISK MANAGMENT
  7. Right click on the disk in question, click EXPAND
  8. Click NEXT on all of the subsequent prompts in the wizard

Here are the two catches:

  1. You must first shut down and deallocate the VM if the disk you are expanding contains the operating system. If it is just a data drive you do not need to reallocate the machine.
  2. If you decide on a CUSTOM SIZE you will still be paying for the size you selected. For instance if you select a CUSTOM SIZE of 400GB, you will be paying for 512GB.

Adding a New Drive to An Azure VM

Adding new drive to an Azure VM without shutting it down. Again, you will need to add the drive then use DISK MANAGER to partition and format the volume.

Changing Azure VM Drive Types

To change the type of a data disk (e.g., from Standard SSD to Premium SSD) on an Azure VM, you also need to deallocate the VM first. This involves stopping the VM, making the change, and then restarting the VM.

Alternatively, if it is just data disk (i.e. no the drive containing the OS), you could detach the disk while the VM is still running, change the disk type, and then reattach it. However, this method can sometimes lead to data loss, so it’s safer to deallocate the VM.

Note that disks can be downgraded just as easily as they can be upgraded. For example, you can move a disk from STANDARD SSD to SPINNING DISK using the same rules as stated above for upgrades.

Changing Azure VM Drive Types or Redundancy Zones

Changing the availability zone of an existing disk directly on the fly is not supported. To move a disk to a different availability zone, you need to follow these steps:

  1. Create a Snapshot: Take a zone-redundant snapshot of the existing disk.
  2. Create a New Disk: Use the snapshot to create a new disk in the desired availability zone.
  3. Attach the New Disk: Detach the old disk from the VM and attach the new disk.

This process ensures that the disk is moved to the new availability zone, but it does require some downtime.

How To Determine Pricing For Azure VM Drives

To figure out the cost of an drive changes on an Azure VM, use . You can change the type, redundancy and size to see what the price is.

  1. azure.microsoft.com/en-ca/pricing/calculator/
  2. Select VIRTUAL MACHINES
  3. Scroll DOWN the page
  4. Select the DISK SIZE you want and note the price beside it

If that is too much work, just click on the screenshot to the right to see what the prices were in USD in January 2024.


That is about all you need to know about expanding Azure VM disks.

Published by
Ian Matthews