How to increase default disk size,

Question

while increasing the disk size, save button is greyed out and it is is Changes to the disk size can be made only when the disk is unattached or the managing virtual machine(s) are deallocated. which is also I am unable to unattached it. Kindly assist

Answer 1

Hello @Chandrakanth Gaikwad

Thank you for reaching out to the Microsoft Q&A platform. Happy to answer your question.

As mentioned in other answers and in document, to increase the disk size of a virtual machine, the disk must be unattached, or the managing virtual machine(s) must be deallocated. This is because the disk size can only be changed when the disk is not in use.

To deallocate the virtual machine, you can use the Azure portal or Azure PowerShell. In the Azure portal, navigate to the virtual machine and select "Deallocate" from the "Overview" page. In Azure PowerShell, you can use the Stop-AzVM command to deallocate the virtual machine.

Once the virtual machine is deallocated, you can then increase the disk size by following the steps outlined in the documentation. In the Azure portal, navigate to the "Disks" section under "Settings" and select the disk you want to expand. Then, select "Size + performance" and choose the new disk size. Finally, select "Resize" to save the changes.

In case you are unable to deallocate the virtual machine, you can try to detach the disk from the virtual machine. In the Azure portal, navigate to the "Disks" section under "Settings" and select the disk you want to detach. Then, select "Detach" to detach the disk from the virtual machine. Once the disk is detached, you can then increase the disk size as outlined above.

Hope this helps!

Please let me know if you have any further queries.

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Answer 2

Hello,

this is expected. Changes to the OS disk can only happen on unattached disks, or when the VM is de-allocated.

https://learn.microsoft.com/en-us/azure/virtual-machines/windows/expand-os-disk

Answer 3

I had this exact situation with a VM that I had shutdown via Start > Shutdown. However just shutting down is not enough. It has to be "stopped" via the Azure control panel or else you won't be able to modify the disk as described by the OP.