VirtualBox emulates hard disks in one of three disk image formats:

  1. VDI: This format is the native file format for VirtualBox,  VirtualBox Disk Image
  2. VMDK: This open format is used by VMWare products such as VMWare Workstation and VMWare Player. It stores data in one or more files bearing “.vmdk” filename extensions. A single virtual hard disk may span several files.
  3. VHD: This format is used by Windows Virtual PC, and is the native virtual disk format of the Microsoft Windows operating system, starting with Windows 7 and Windows Server 2008 R2. Data in this format are stored in a single file bearing the “.vhd” filename extension.

VirtualBox virtual machine can, therefore, use disks previously created in VMware or Microsoft Virtual PC, as well as its own native format.

VMWare Products use the VMDK format as the native file format:

  • VMware Workstation
  • VMware Player
  • VMware Server
  • VMware Fusion
  • VMware ESXi
  • VMware ESX

Open Virtualization Format (OVF) is an open standard for packaging and distributing virtual appliances or, more generally, software to be run in virtual machines.

An OVF package structure consists of a number of files: a descriptor file, optional manifest and certificate files, optional disk images, and optional resource files (such as ISO’s). The optional disk image files can be VMware vmdk’s, or any other supported disk image file. More information about the OVF format standard can be found here.

Use unzip tools to open .OVF files.