Hyper-V VHD or VHDX? Advantages, Limitations, and Disadvantages

When you have the choice between VHD and VHDX for Hyper-V virtual disks, you may want to consider the following advantages, disadvantages, and limitations of each virtual disk format:


VHD Features

VHDs work on Windows Server 2008, 2008 R2, 2012 and 2012 R2.  Hyper-V on Windows 8 also supports it as well as Virtual PC and Virtual Server, remember those? Hence if you want to move your disks around different Windows host versions, VHD is the way to go.

VHDs use a 512 byte block size internally

VHDs are limited to a 2TB

VHDs can’t be resized live.


VHDX Features

Microsoft is quite an anxious animal. They put a lot of work into the VHD format, now VHDX, to better compete with VMware. Hence, a lot of improvements were added:

Live resize of virtual disks.

4KB block size, aligns well with modern hard drives (3TB+) which also use 4KB internally. Hence, it’s best to format NTFS partitions using the default cluster size of 4KB.

Improved handling of power failure conditions

Better handling of snapshots

Up to 64TB disk sizes supported

Only supported on Windows 8, Windows Server 2012 and later.


For best backup performance, use BackupChain to back up your VHD and VHDX Hyper-V virtual machines.