VMware cries foul over Microsoft virtualisation

The battle to control the virtualisation market has heated up with the launch of a white paper from VMware, which accuses Microsoft of anti-competitive practices.

In language reminiscent of Microsoft's anti-trust battles in the US and its ongoing struggle with the European Union, VMware claimed that the software giant is "forcing [its] specifications and APIs on the industry", and "trying to restrict customers' flexibility and freedom to choose virtualisation software".

Tension between the two companies over the issue has been building for some time. VMware is the market leader with 53 percent of the market, according to analyst group Forrester. From a slow start in virtualistion, Microsoft is in third place with 9 percent.

It is a fast-growing market. "Marketing professionals across the technology industry are climbing on the server virtualisation bandwagon," said Forrester analyst, Frank Gillett, in his report.

In its white paper, which was published last Friday, VMware charged that Microsoft is struggling in some areas because of deficiencies in its own product areas, and is trying to find ways around that by denying access to competing products.

"Microsoft does not have key virtual infrastructure capabilities, like VMotion [a key VMware application]", VMware wrote in the white paper, "and they are making those either illegal or expensive for customers." VMware pinpoints the virtual desktop, claiming that as Microsoft does not have a virtual desktop of its own, it is "denying it to customers".

In addition, Microsoft is "moving to control this new layer that sits on the hardware by forcing [its] specifications and APIs on the industry".

VMware's basic charge is that Microsoft is not acting in the interests of the industry or the public by promoting virtualisation fairly. Instead, it is "attempting to force an integrated virtual hardware/operating system/application stack for [its] operating system and applications", the company's white paper argues.

Other claims made in the white paper include:

• There are prohibitions on running Microsoft virtual machines on third-party virtualisation software
• Microsoft's virtual hard disks are now configured to de-activate themselves if they are run on any virtualisation product besides Microsoft Virtual PC or Virtual Server
• Windows Vista only allows customers to transfer their virtual desktop to another system once
• Microsoft is not letting other virtualisation vendors or open-source projects use its virtualisation APIs

Microsoft has not yet responded directly to VMware's criticisms. When asked for comment it pointed to a general statement by Mike Neil, Microsoft's general manager for virtualisation, which makes it clear that for Microsoft, the route to virtualisation is through a Microsoft operating system only -- its next-generation server, code-named Longhorn. Writing in his blog on Monday, Neil wrote: "Our desire is to bring hypervisor-based virtualisation to Windows Server with Windows Server Longhorn," he wrote.

According to VMware, the problem is Microsoft's focus on one operating system. "Customers require freedom of choice to implement both Microsoft and non-Microsoft applications running on Windows with any chosen system virtualisation layer," the white paper says. By prohibiting the use of Microsoft virtual machines with those from other vendors, "Microsoft virtualisation products eliminates choice and competition in the marketplace".

VMware had not responded for requests for further comment at the time of writing.

Colin Barker reported for ZDNet UK from London