VHD stands for Virtual Hard Disk, a very common virtual drive file format mostly used by Oracle VM VirtualBox and Microsoft Windows Virtual PC (commonly termed as Hyper-V). These files are virtual but just act as a physical HDD to Hypervisors which in turn contain files and folders, its own file system and disk partitions.
A Virtual Hard Disk is alone an isolated hard disk giving users mobility to run multiple operating systems simultaneously on one computer.
Based on their allocation pattern there are mainly 4 different types of VHDs
VHDX is a virtual machine disk file format created with Microsoft Hyper-V (Windows Server Virtualization tool), supported on Windows 8, Windows Server 2012 and 2012 R2.
A virtual machine disk file captures the instance of a virtual machine state and stores that information as a file, with the upgrade in size of these virtual machine disk files from 64TB to 2TB, allows virtual disks to capture a detailed version of the instance of operating system.
The change in block size from 512 byte to 4kb makes it in coordination with today's storage devices and suitable to format NTFS partitions.
VHDX keeps and regularly updates the changes in metadata periodically making it possible to fight against the corruption situations regarding power failures.
Supported Hypervisors For WindowsMicrosoft Windows Virtual PC Microsoft Virtual Server Oracle VM VirtualBox VMware Workstation 11
Supported Hypervisors For MAC
Oracle VM VirtualBox VMware Fusion 7
Supported Hypervisors For Linux
Oracle VM VirtualBox VMware Workstation 11