Virtual Hard Disk (VHD)

Please help to improve this article by expanding it. Further information might be found on the discussion page.

The Virtual Hard Disk (VHD) commonly uses the .vhd extension.

This format is used to store virtual disk images by:

• Microsoft Virtual PC
• Microsoft Virtual Server
• Microsoft Hyper-V Server

Image types

There are multiple types of Virtual Hard Disk (VHD) images:

• Fixed-size hard disk image; the image contains all data
• Dynamic-size (or sparse) hard disk image; the image contains used data only
• Differential (or differencing, or delta) hard disk image; the image contains changes relative to its parent image

Snapshots

Hyper-V has functionality to create snapshots.

These snapshots are stored in Snapshot Differencing Disk (AVHD) files which commonly uses the .avhd extension.

The snapshot can be interdependent on one-another, because they are differential images of the previous snapshot.

Windows integration

"Disk Management" in (at least) Windows 7 support attaching and creating Fixed and Dynamic VHD image files.

See Also

• Disk Images

External Links

• VHD (file format), by Wikipedia
• Virtual Hard Disk Image Format Specification, by Microsoft, October 2006
• Virtual Hard Disk (VHD) image format, by the libvhdi project, September 2012

Snapshots

• Hyper-V Concepts - Snapshots
• Virtual Machine Snapshotting under Hyper-V
• Hyper-V SnapShot Files – AVHD and VHD? What The ?
• Manually Merge .avhd to .vhd in Hyper-V