What is a .vmdk file?
VMware Virtual Disk · Disk image · VMware · 1999
A .vmdk file is a VMware virtual disk, the file that stores a virtual machine's hard drive. It is the VMware equivalent of Hyper-V's VHDX, and is widely supported by other hypervisors too.
What is a .vmdk file used for?
Monolithic sparse VMDKs start with the magic KDMV, while some VMDKs are a small text descriptor pointing to separate data extents. Either way the file represents a whole virtual disk.
VMDK is one of the most portable VM disk formats: VirtualBox, qemu and cloud import tools all read it, which is why it is common for distributing appliances.
What opens a .vmdk file?
The .vmdk format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- VMware Workstation
- VirtualBox
- qemu-img
macOS
- VMware Fusion
- VirtualBox
- qemu-img
Linux
- qemu / qemu-img
- VirtualBox
- VMware
Open a .vmdk file step by step
- Confirm the file really is a .vmdk. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with VMware Workstation or VirtualBox.
- On Mac, use VMware Fusion or VirtualBox.
- On Linux, try qemu / qemu-img or VirtualBox.
- Still stuck? Convert the .vmdk to vhd, which opens more widely.
Why can't I open my .vmdk file?
Almost always because no installed app understands VMDK. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .vmdk at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .vmdk file
You can convert a .vmdk file to vhd, vhdx, img, qcow2 using a conversion tool or the export menu of an app that opens it.
What is the .vmdk file signature (magic bytes)?
A .vmdk file starts with the hex bytes 4B 44 4D 56, which read as KDMV in ASCII. Programs identify VMDK by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for VMDK. For a full breakdown, see the VMDK (VMware disk) file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 4B 44 4D 56 | 0 | KDMV | 'KDMV' (sparse); some VMDKs start with a text descriptor |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .vmdk file?
A .vmdk file is a VMware virtual disk, the file that stores a virtual machine's hard drive. It is the VMware equivalent of Hyper-V's VHDX, and is widely supported by other hypervisors too.
How do I open a VMDK file?
Attach it to a VM in VMware or VirtualBox, or convert and inspect it with qemu-img. It is a virtual hard disk, not a document.
Can VirtualBox open a VMDK?
Yes. VirtualBox reads VMDK directly; when creating a VM you can attach an existing .vmdk as its disk.
How do I convert VMDK to VHD?
Use qemu-img: qemu-img convert -O vpc disk.vmdk disk.vhd, or the conversion tools built into VirtualBox.
Comparisons
Related formats
Sources
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