Open Source Weblog

Microsoft already provides technical support for Linux running on Virtual Server R2, following its launch at the LinuxWorld Conference and Expo in April. The latest agreement will enable Longhorn server to run Linux running on XenEnterprise.

It will also provide interoperability between Linux running on Xen on Windows, and Windows running on Microsoft's own Windows hypervisor on the Longhorn Windows Server. Steve Ballmer mooted plans for a hypervisor in April 2005 at the company's Microsoft Management Summit in Las Vegas.

Plans were confirmed by Microsoft's corporate vice president of server and tools marketing and solutions, Andy Lees, in June last year.

Earlier this year Xen quietly licensed the Virtual Hard Disk (VHD) format from Microsoft, enabling it to import virtual machines created with Microsoft Virtual Server.

Previously Xen had problems with Windows given that its para-virtualization approach requires a port of the operating system to compile for the Xen Hypervisor.

The deal with Microsoft is a return to a mutually beneficial relationship between the two, however, as Xen creator Ian Pratt had access to the source code to Windows XP from Microsoft when creating Xen 1.0 at Cambridge University, which allowed the Xen team to put Windows XP inside Xen partitions.

Anyone waiting for the new Microsoft/Xen-developed functionality would be advised not to hold their breath, however. Microsoft said it plans to release a beta of Windows Server virtualization by the end of this year, with a release to manufacturing due six months after the release to manufacturing of Windows Server Longhorn.

That is not expected until the end of 2007, which means it could be at least two years before the Microsoft XenSource deal bears fruit.