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THE FILE FIELD GUIDE
.vdi

VirtualBox Virtual Disk

Virtual Machines

VDI is a VirtualBox disk, not the VM’s full settings, memory state or snapshot tree. Dynamic host file size can differ from guest capacity; size alone does not imply missing content.

What it is used for
VirtualBox virtual hard-disk storage
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 in VirtualBox

Identify current state and differencing disks.

  1. Shut down and back up the VM set.
  2. Inspect VDI and parent/child relationships in Media Manager.
  3. Identify the disk referenced by the current VM.
Attach a copy to a VM

Distinguish file copying from managed cloning.

  1. Create a copy through a supported clone/migration workflow.
  2. Inspect destination storage and firmware.
  3. Verify OS/data in a test environment.
Migrate the current state

Do not deliver a difference image alone.

  1. Identify the intended state and parent chain.
  2. Use supported clone/export to create an appropriate independent output.
  3. Compare capacity, boot and data on the copy.

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

Troubleshooting by symptom

  • Registration conflict: review existing media/identifiers before changing them.
  • Missing parent: inspect snapshot/linked-clone dependencies.
  • Different sizes: distinguish virtual capacity from host allocation.
  • Recent data missing: inspect the active difference image.
  • VDI does not shrink: distinguish allocation and supported compaction.
  • No boot after attach: compare controller and firmware.

VDI → VMDK / VHD

  1. Establish dependencies of stopped media and use supported copy/conversion.
  2. Validate output content/capacity and retain the original VM set.
  3. Compare representative data with the intended source state.

Disk conversion does not transfer settings/memory state; identify parents and desired state.

Dynamic allocation and parent chains

Compare virtual size/allocation and identify parent relationships.

Example: identify the active snapshot chain rather than assuming the base is current.

Source for these steps：Oracle · Virtual Storage — VirtualBox 7.2 / Oracle · Working with Virtual Machines — VirtualBox 7.2

History versus independent copy

Choose between preserving history and exporting the current state.

Source for these steps：Oracle · Virtual Storage — VirtualBox 7.2 / Oracle · Working with Virtual Machines — VirtualBox 7.2

Related-format differences

Related-format differences
Format / methodRoleWhat to verify
VDIVirtualBox diskUUID/parent
Differencing VDIChanges from parentNeeds parent
Independent cloneCopy of selected stateHistory differs

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

Can I move everything with VDI alone?

Check settings, parents and saved state.

Is dynamic allocation compression?

Allocation and ordinary compression differ.

Can I delete its parent?

Establish differencing/linked-clone dependencies first.

Can one snapshot VDI restore the VM?

Parents/configuration may be required; preserve a complete supported backup.

Does freeing guest space immediately shrink VDI?

Guest free space and host allocation differ; inspect supported compaction requirements.

Format facts: name, steward and MIME type
Formal name
Virtual Disk Image
Steward / specification
Oracle VirtualBox
MIME type
Depends on the producer or server; an extension alone does not establish a MIME type.

Primary and official sources