Virtual hard disk
From WikiCover
On September 11, 2007, Microsoft and Citrix Systems have strengthened their integration alliance in the desktop and application delivery market by standardizing on the Microsoft Virtual Hard Disk (VHD) format as a common runtime environment for both virtualized operating systems and applications. This collaboration will result in future versions of Citrix's Desktop Server and virtual application solutions adopting the Microsoft VHD format. At the same time, Microsoft plans to adapt a future version of Microsoft SoftGrid Application Virtualization for both the desktop and Terminal Services to the VHD format.
Citrix announced its intention to acquire virtual infrastructure vendor XenSource, extending its capabilities into both server and desktop virtualization. Citrix uses the VHD format today and plans to extend its support in the future to include operating system streaming to both servers and desktops. XenSource also supports VHD as its native runtime format for virtual machines.
Microsoft's VHD format has been available under its Open Specification Promise since October 2006. The Open Specification Promise is a promise from Microsoft to every individual and organization in the world to make use of this patented technology for free, now and forever when implementing specified open standards. The VHD format, which has been available as a commercial license since May 2005, captures the virtual machine operating system and the application stack in a single file. With the VHD format as a freely available specification, Microsoft is contributing to the continued expansion of virtualization by fostering interoperability among commercial software solutions, including open source.