File extension
.vmdk
VMware Virtual Machine Disk
.vmdk files are VMware Virtual Machine Disk images: a disk format used by VMware products and supported by many other virtualization tools.
Known meanings
Formats and reference material for .vmdk
VMware Virtual Machine Disk
Virtual disk format for VMware virtual machines, with descriptor and extent files
Details
Format notes
VMDK
VMDK (Virtual Machine Disk) is the virtual disk format of VMware Workstation, Fusion, Player and ESXi. It was designed by VMware, and has become a common interchange format; it is also supported by VirtualBox, QEMU and others, and is the disk format used inside OVA packages.
Structure
A virtual disk can consist of a small text descriptor file that describes the
disk geometry, type and list of extents, plus one or more extent files holding the
data. The descriptor can also be embedded in a single file. Sparse extents begin
with the magic KDMV, followed by a header with capacity, grain size and the
location of the grain directory. Common disk types include monolithic sparse,
monolithic flat, split into 2 GB extents, and, on ESXi, -flat and -delta
extents. Snapshots are stored as child disks that refer to a parent.
Adoption And Tooling
VMware products create and manage VMDK files, and the vmware-vdiskmanager and
qemu-img tools can convert them to and from raw, qcow2 and VHD formats. Open
source libraries such as libvmdk provide read access without VMware software.
VMware has published a technical note on the format, but older links to it have
moved, so consult current VMware documentation.
Preservation And Security Notes
Keep descriptor files and all extent files together, along with any parent disks, since a VMDK that refers to missing extents cannot be opened. Disk images contain whole file systems, including deleted data and possible credentials, and should be treated accordingly.
Further Reading
- libvmdk project (libyal):
https://github.com/libyal/libvmdk