How to Help Hyper-V Increase Virtual Disk Size?

February 18, 2019

This article is about helping Hyper-V Windows Server 2008 or 2012 (R2) increase virtual disk size, in this article, we take virtual machine hard disks in Hyper-V Windows Server 2008 as an example and will recommend you the best server partition software.


First, let me clarify that this article is based on Hyper-V 2.0 (Windows Server 2008), this might not apply to Hyper-V 3.0 (Windows Server 2012). For Windows Server 2012 (R2), please visit another post.

Why need to increase virtual disk size in Hyper-V 2008?

Have you ever troubled with the problem of “out of Disk Space on Drive C” of a Virtual Machine Running Windows Server 2008 (R2)? If yes, then this article may solve your problem.

Firstly we will help your Hyper-V increase virtual disk size, so at the hardware level – the VM’s .vmdk file. Once this is completed, we will get into the virtual machine and make the necessary changes through the operating system GUI in order to take advantage of the additional space that has been provided by the hard disk being extended.

Put simply, there are two parts. The first one is making the VHD bigger. The second one is extending the system partition to use all the new space. Thus, your problem solved!

The way to increase virtual disk size in Hyper-V Windows 2008

Part I - Increase Virtual Disk Size

Shutdown the server, open Hyper-V Manager and select Edit Disk. In the Welcome screen click Next and then click on the file path of the VHD that you want to increase and then click Next again. Then will be on the Choose Action window, certainly choose Expand, and then click Next. Enter a new size of the virtual disk size and click Next. In this example used the VHD had 648.45 GB will be increased to 698.49 GB.

Choose Action

Choose Action Page

Edit Virtual Hard Disk

Expand VHD page

You can also use the PowerShell script if you need to to automate the above process. For information about PowerShell script, please search from them Google, in order to save space, I will not explain it here.

Part II – Extending the drive C To use the full larger VHD unallocated capacity

Once the virtual disk size increased at the underlying hardware level has completed as in the previous part, you are now ready to extend the system partition through the Windows GUI. This process is extremely simple and only requires a few mouse clicks.

Extend Volume is grey

Open the Windows Server 2008 built-in Disk Manager, right click C: drive, you may find the “Extend Volume” is invalid. Am I wrong? Not a few mouse clicks! Oh, sorry, I forget to tell you a tool - AOMEI Partition Assistant Server Edition. It is a third-party partition manager. With it, you can extend the system partition easily.

Download it first, install and run. Right click the C: drive and select “Merge Partitions”.

Merge Partitions

In the pop-up window, check the unallocated space. Click “OK” to go back the main interface.

Tick Unallocated Space

You can see some changes. Partition C has been become larger. In fact, there are several steps, move first, then resize. Using AOMEI Partition Assistant Server just hidden these, which is more powerful and convenient than Windows Server Disk Management. Click “Apply”, wait a minute, the start trouble “out of Disk Space on Drive C” will be solved totally.


More about AOMEI Partition Assistant

In this tutorial, AOMEI Partition Assistant Server works perfect on Window Server 2008. In reality, AOMEI Partition Assistant Server Edition as a professional partition tool not only works well on all Windows Server operating systems: Windows Server 2012(R2), Windows Server 2003, but also runs normally on Windows XP, Window Vista, Windows 7 and Window 8/8.1. In functional aspect, it is full scale: create partition, copy partition, split partition, convert partition style, and more. With AOMEI Partition Assistant, Window Disk Manager can be replaced entirely.