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VMDK File Format

Virtual Machine Disk file for VMware virtual machines

The VMDK file extension is associated with the Virtual Machine Disk (VMDK) format specification used with VMware virtual machine files. 

Non-virtualized computers load and execute hundreds or thousands of individual files, including operating-system kernel files, device drivers, application components and data files. Virtualization abstracts the software from the underlying hardware and puts all the constituent data for a given virtual machine (VM) in a single disk file. The disk file is essentially a complete and independent virtual machine. 

A disk file with the VMDK extension is a virtual machine using VMware virtualization products or other platforms that support VMDK files such as Sun XVM, QEMU, or VirtualBox.

The VMDK file format competes with the Microsoft Virtual Hard Disk (VHD) format used with Virtual Server and Hyper-V hypervisors.


Learn more about VMDK files:

Stephen J. Bigelow discusses the VMDK file format in this tip. 

See questions and answers about virtual machines. offers news, learning resources and expert advice about server and desktop virtualization.

This was last updated in September 2010
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