Azure Infrastructure: Azure Windows VM Disk Size Increase

This document walks through the process of increasing an azure windows virtual machine. This process is required whenever a virtual machine experiences a workload increase needs more storage for its data.

Step 1: Backup Virtual machine

It is always a good practice to backup the virtual machine before increasing the O.S or Data disk size.
Azure backup can be used to perform this backup.

Step 2: Stop & deallocate Virtual machine

After successfully backing up the virtual machine is it required to stop the VM and wait for it to be in the deallocated state before upgrading the disk space. Please see schreenshot.

Searching for the module — VM Status (enlarged image)

Step 3: Increase disk size

As seen below the current disk has a storage size of 128 GB.

Searching for the module — VM Status (enlarged image)

Next select the disk size, which in this case is 512 GB and upgrade size.

Searching for the module — VM initial size (enlarged image)

Once upgrade is complete, you will receive the following notification.

Searching for the module — VM new size (enlarged image)

Step 4: Start Virtual machine

Once the disk size upgrade is completed, you should restart the virtual machine and wait for it to show as running.

Searching for the module — VM Running status (enlarged image)

Step 5: Log into the Virtual Machine & perform disk extension

It is important to note that increasing the size disk via azure console is not sufficient to increase the disk on the virtual machine.
To perform a virtual machine disk upgrade, you must log into the virtual machine.
In the virtual machine, Search for Server Manager > then Tools > Computer Management > Disk management.

Searching for the module — Disk Management (enlarged image)

In the disk Management, you will the amount of disk space that is unallocated, the formula is usually desired Size – Current size.
In this scenario, we have 385.00 GB of unallocated size.
To extend the size, you have to right click on the disk tab Windows (C:) and select Extend Volume.

Searching for the module — Disk Extension (enlarged image)

After clicking Extend volume, the following tab will show, click on Next.

Searching for the module — Disk Extension Wizard (enlarged image)

-After clicking on next, it will the desired disk size growth, after confirming, click on Next and finish.

Searching for the module — Disk Extension Wizard (enlarged image)

Step 6: Validate disk size increase

To validate disk size increase, go to File Explorer and look at the the drive.

Searching for the module — Disk Extension Wizard (enlarged image)

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Updated on August 12, 2025