How to Expand VHD in Windows Server 2012 Hyper-V?

December 30, 2014

To expand VHD in Windows Server 2012(R2) Hyper-V, now it is very easy. Make good use of different tools, a few steps will complete the task. In this article, I would like to recommend you a great tool named AOMEI Partition Assistant Server Edition.

Improvements of Windows Server 2012 Hyper-V

Compare with previous releases of Hyper-V, Windows Server 2012 VHDs can be much bigger, and even safer, and have shrinkable size and capacity. When you using the Hyper-V virtualization role in Windows Server 2012, you may have some virtual hard disks to manage. Once new virtual machines (VMs) are created, they are assigned one or more VHDs of specific types and sizes, and which VHDs new VMs receive are usually associated with a VM template or gallery image. After deploying the standard image VM, it’s frequently necessary to modify the VHD parameters over the lifecycle of the VM, for example, to expand the maximum size of one or more VHDs.

Expand VHD in Windows Server 2012 Hyper-V

To do this you need to open the Edit Virtual Hard Disk Wizard (by selecting Edit Disk from the Hyper-V manager), select the virtual hard disk that you want to increase, of course, select Expand option on the Choose Action page and then type a new size of the virtual hard disk that you want.

Because the guest is Windows Server 2012, you can create a Storage Space within the VM, as it’s quite easy to just add additional disks to an existing Storage Space extending its size. Please don’t try and create a Storage Space in a VM using passthrough disks, as when the host reboots, the host would see the disks have a Storage Pool and try to claim it.

Above part can be as preparation. Next is the key point. How to use the unallocated volume is key.

Case I

The empty space is in date disk, to expand this VHD in Windows Server 2012 Hyper-V, you just need to use Windows Server 2012 built-in Disk Manager, right click partition H, you can find the option “Extend Volume” is active. Choose it, then click Next to continue following every guides.

Extend Volume in Disk Management

Case II

I think this is the most often case, users expand VHD in Windows Server 2012 Hyper-V with the purpose of extending system partition on guest. Unfortunately, in this situation, Windows Server 2012 built-in disk management program can’t help you. You see, the “Extend Volume” is gray, which means it is invalid.

.Extend Volume is grey

Why? Because the unallocated volume is far from the C drive, while using Disk Manager to extend, the unallocated partition must be behind the system partition. Don’t worry, there are some third-party to break this limitation.

In this article, I suggest you try AOMEI Partition Assistant Server Edition. Download it from AOMEI official website, install and launch. Right click C: drive, you can find a option named “Merger Partitions”, select it.

Merge Partitions

In the pop-up window, select partition C and the unallocated space. Click “OK”.

Select Partitions

Back to the main menu, you can see that C: drive has been expanded. There are four pending operations. You may think maybe you can do these with Disk Manager, although it is said so, it is hard to do. Backup date? Transfer date? Waste time and may cause date loss. So using AOMEI Partition Assistant Server is better, fast and safe. At last, just click “Apply” to commit the changes. Wait a minute, system partition in Windows Server 2012 Hyper-V will be expanded successfully.


More about AOMEI Partition Assistant

AOMEI Partition Assistant Server Edition is an all-in-one partition management software. It can take the place of Windows Server 2012 Disk Manager completely. And can do many things that Disk Manager can’t do. Such as migrate OS to SSD, rebuild MBR, etc. Besides it supports Windows Server 2012(R2). Windows Server 2008(R2), Windows Server 2003, Windows XP/7/8 are all perfect supported.