Fixed VHDs consist of a raw disk image followed by a VHD footer (512 or formerly 511 bytes). The following types of VHD formats are supported by Microsoft Virtual PC and Virtual Server: VHDs are implemented as files that reside on the native host file system. VHDX was added in Hyper-V in Windows Server 2012 to add larger storage capacity, data corruption protection, and optimizations to prevent performance degradation on large-sector physical disks.
The ability to directly modify a virtual machine's hard disk from a host server supports many applications, including: This method enables developers to test software on different operating systems without the cost or hassle of installing a second hard disk or partitioning a single hard disk into multiple volumes. A Virtual Hard Disk allows multiple operating systems to reside on a single host machine.
