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.vhd

Virtual Hard Disk

Virtual Machines

VHD is a virtual-disk container with fixed/dynamic/differencing variants. Differencing disks need parents. Container support, filesystem readability and guest bootability are separate conditions.

What it is used for
Virtual hard disks and differencing media
What the file contains
Binary data
All sections, questions and sources

Content reviewed： · Editor：Kai

Opening steps

Choose your environment or purpose to see its steps.

Inspect the virtual disk

Separate VM use from content inspection.

  1. Ensure the disk is not in use.
  2. Back up configuration, VHD and differencing files.
  3. Inspect parent requirements and intended state.
Read contained files

Use a read-only copy on supported Windows.

  1. Check supported read-only mounting.
  2. Attach the copy and inspect partitions/filesystems.
  3. Inspect required files and detach afterward.
Convert disk format

Convert an unattached offline disk.

  1. Check offline state and output space.
  2. Create a separate output with supported tools such as Convert-VHD.
  3. Compare capacity, partitions and required data.

Menu labels and support vary by app, OS and version. Preserve the original before making changes.

Troubleshooting by symptom

  • Image in use: review VM/process access.
  • Initialization prompt: check filesystem/encryption instead of assuming empty data.
  • Missing parent: establish differencing dependencies.
  • Volume absent after mount: inspect partitions and drive assignment.
  • Output lacks space: compare fixed/dynamic allocation and virtual capacity.
  • No VM boot: inspect firmware/controller.

Stopped VHD → VHDX or supported format

  1. Check tool support/dependencies and use offline conversion.
  2. Write separately and validate data, capacity and target support.
  3. Compare representative files with the intended source state.

Conversion does not guarantee whole-VM/snapshot migration; validate before replacing originals.

Attachment versus VM boot

Mounting for inspection does not boot the guest; choose the workflow by purpose.

Example: file inspection can use supported read-only mounting separately from guest boot.

Source for these steps：Microsoft · Convert-VHD / Microsoft · Mount-DiskImage / Microsoft · Hyper-V checkpoints

Preserve differencing state

Preserve parent/child state and use complete supported VM backups.

Source for these steps：Microsoft · Convert-VHD / Microsoft · Mount-DiskImage / Microsoft · Hyper-V checkpoints

Related-format differences

Related-format differences
Format / methodRoleWhat to verify
VHDVirtual hard diskParent/format limits
VHDXAnother virtual-disk formatTool support
CheckpointState managementConfiguration/deltas

Handling and security

Stop the VM and preserve originals/parents. Disks may contain credentials or deleted data; avoid public converters and shared host connections for unknown guests.

Questions and answers

Does mounting boot the OS?

Attaching content and booting differ.

Should I initialize to open it?

Preserve and identify the existing data first.

Can renaming produce VHDX?

Use real supported conversion.

Does an OS-bearing VHD boot in every VM?

Firmware, controller and guest support still matter.

Does read-only mode decrypt the disk?

No; authorized keys/recovery are still required.

Format facts: name, steward and MIME type
Formal name
Virtual Hard Disk
Steward / specification
Microsoft / compatible virtualization tools
MIME type
Depends on the producer or server; an extension alone does not establish a MIME type.

Primary and official sources

  • Platform documentationConvert-VHD

    Reference for offline VHD/VHDX conversion.

    Microsoft · Link checked：
  • Platform documentationMount-DiskImage

    Reference for supported Windows disk-image mounting.

    Microsoft · Link checked：
  • Official documentationHyper-V checkpoints

    Checkpoint types, management and merging.

    Microsoft · Link checked：