Virtual disks: VHD vs VHDX, fixed, dynamic and differencing disks; shared VHDX / VHD Set

A Hyper-V virtual hard disk is a file on the host that the VM sees as a physical disk. There are two formats. VHD is the original format, limited to about 2 TB (2,040 GB) and 512-byte sectors; it survives mainly for compatibility with older systems and some tools. VHDX, introduced with Windows Server 2012, supports disks up to 64 TB, 4 KB logical sectors that match modern physical disks, an internal metadata log that protects against corruption after a power failure, and TRIM/UNMAP so freed space can be returned to the storage. Generation 2 VMs boot only from VHDX. Use VHDX unless you have a specific reason not to.