VHD/VHDX (virtual hard disk)
Also known as: vhd file, vhdx, virtual hard disk
A VHD (and its successor VHDX) is a single file that acts as a complete virtual hard disk, holding its own partitions and file system. Windows and virtual machines use it as a self-contained disk image. These files can grow very large as their contents fill up.
- A file that acts as a full virtual hard disk
- VHDX is the newer, larger-capacity version
- Can occupy large amounts of host storage
A disk inside a file
VHD stands for Virtual Hard Disk. The file behaves like a physical drive: it contains its own partition table and file system, and software treats it as a separate disk you can format, mount, and read from. VHDX is the newer version, with support for larger capacities and better resilience.
A virtual machine stores its drive as a VHD/VHDX, and Windows can also mount one directly so it appears as an extra drive letter in File Explorer.
Why VHD files get large
A virtual disk can be fixed, reserving its full size up front, or dynamic, growing as data is added. Dynamic disks often keep space even after files inside are deleted, so a VHDX can stay large on the host even when the virtual machine looks half-empty.
Old or unused virtual disks are a common source of hidden storage use, since a single file can represent tens of gigabytes of a guest system.