XenSource Licenses Microsoft's VHD As Format War Begins

XenSource has licensed Microsoft's Virtual Hard Disk (VHD) format for its upcoming Xen 3.0-based virtualization server, called XenEnterprise.

As LinuxWorld Expo and Open Solutions World kick off in Boston, XenSource announced the deal with Microsoft and formally launched XenEnterprise, which is slated to begin shipping in the second half. XenSource is the Palo Alto, Calif.-based commercial spinoff of the Xen open-source project.

Meanwhile, virtualization market leader VMware stoked the fires by announcing Monday availability of its own virtual disk format specification at no cost.

For XenSource customers, supporting Microsoft's VHD format will enable XenEnterprise to run high-performance Windows guest workloads on Xen 3.0, according to XenSource. XenEnterprise will virtualize Windows, Linux and other operating systems in production environments and offer built-in physical-to-virtual tools, the company said.

The deal illustrates the increasing “co-opetition” and competition in the virtualization software market.Microsoft's Virtual Server and future Windows Server hypervisor will compete head-on against Xen 3.0, the open-source virtualization hypervisor developed by the Xen open-source project.

Xen 3.0, for example, is being integrated into two upcoming Linux server operating environments: Novell's SUSE Linux Enterprise Linux 10 and Red Hat Enterprise Server 5.

Microsoft said it would license its VHD format last April.

One Xensource executive said the virtualization extensions in Intel and AMD processors will enable Windows workloads to run on Xen 3.0, but use of Microsoft's VHD format will ensure high performance.

"It's quite a strategic move on the part of Microsoft to license this format to us," said Simon Crosby, CTO of XenSource. "It will meet a key need for us to deliver high-performance virtualization."At LinuxWorld, VMware--which competes against Microsoft and will compete against Xen open-source virtualization--responded by announcing the availability of its virtual machine disk format specification to developers and vendors without royalties, restrictions or the need for licensing.

In October, VMware said it was working with the Distributed Management Task Force (DMTF) to create common interfaces.

VMware said a virtual machine encapsulates an entire server or desktop environment in a single file. Patch, provisioning, security, management, backup and other infrastructure solutions for virtual machine environments all depend heavily on the virtual machine disk format, according to the company.

Akimbi Systems, Altiris, BMC Software, IBM, PlateSpin, rPath, Surgient, Symantec and Trend Micro said they will support VMware's specification.

One solution provider with expertise in virtualization said it remains unclear how well Xen will be adopted vis-a-vis leading proprietary solutions."I have not yet encountered any demand for Xen hypervisors. We have been engaging with enterprise customers that are embracing horizontal virtual infrastructure initiatives, and given that VMware and Microsoft dominate this space, these are the virtualization platforms of choice," said John Dodge, CIO of Foedus, New York.

The format war is on, although VMware also said Monday it’s committed to supporting any other open virtual machine disk formats that are broadly adopted by customers.