VMDK (VMware disk)
Also known as: vmdk file, vmware disk, virtual machine disk
A VMDK is the virtual disk format created by VMware. The file stores a virtual machine’s entire drive — its partitions, file system, and data — as a self-contained disk image, and it can occupy a large amount of space on the host computer.
- VMware’s virtual machine disk format
- Stores a guest system’s full drive as a file
- Can take up large host storage; may not shrink on delete
What a VMDK represents
VMDK stands for Virtual Machine Disk. It holds everything a guest operating system sees as its hard drive: the partition layout, file system, installed software, and files. The host treats it as one (or several) ordinary files, while the virtual machine treats it as a physical disk.
A single VMDK can also be split across multiple files, and other virtualization tools can often read or convert the format.
Storage impact
Like other virtual disks, a VMDK can be preallocated to its full size or grow on demand. Growable disks frequently hold onto space after data is deleted inside the VM, so the file on the host stays large even when the guest reports free space.
VMDK is VMware’s counterpart to the VHD/VHDX format used by Microsoft tools; both are disk images, just from different ecosystems.