Consumers cannot run home versions of Windows Vista as virtual machines because virtualization is not mature enough for broad adoption, says Microsoft.
A Microsoft spokesperson told ZDNet Asia: "For production machines and everyday usage, virtualization is a fairly new technology and one that we think is not yet mature enough for broad consumer adoption."
According to Microsoft's Windows Vista End User License Agreement (EULA), the platform's Home Basic and Home Premium editions cannot be run as a virtual machine (VM). Such restrictions do not apply to the business versions of the OS.
"Today, customers using this technology are primarily business customers addressing application compatibility needs or technology enthusiasts," the spokesperson said. "For everyday use, Windows Vista Home and Home Premium cannot be installed in any virtual machine technology, but Business and Ultimate versions can. Each virtual installation of Windows requires a new license just as it was for Windows XP."
Microsoft said developers who obtain Windows Vista Home Basic or Windows Vista Home Premium through their MSDN (Microsoft Developer Network) subscription may use those programs within a virtual machine to assist them in designing, developing, testing and demonstrating their programs.
Michael Silver, Gartner's research vice president, wrote on the analyst company's blog that like Windows rootkits, there is a risk that VM rootkits can be installed unbeknownst to the consumer.
"Microsoft says that consumers don't understand the risks of running virtual machines, and they only want enterprises that understand the risks to run Vista on a VM," Silver said.
"So, Microsoft removes user choice in the name of security," he said.
According to the Gartner analyst, Microsoft's decision is derived from a license restriction, not a technical one. So, a consumer who wants to run Windows Vista under VMware on a Mac, for instance, will violate Microsoft's EULA, he added.
"The other option is to pay Microsoft US$300 for Windows Vista Business or US$399 for Windows Ultimate, instead of US$200 for Home Basic or US$239 for Home Premium," Silver suggested.
"[But] does paying US$60 or US$100 more mean they understand the risks?" he said. "We suppose that to Microsoft, it does [mean that]. Or maybe for the extra money, Microsoft just doesn't care as much."
Dan Chu, VMware's vice president of emerging products and markets noted in his company blog that the restriction is in stark contrast to the several million users of software such as VMware Workstation and VMware Player, who have adopted virtualization for their general-purpose desktops.
"There has been broad criticism of this policy from customers and industry observers who have been clear that such moves to arbitrarily inhibit the use of operating systems are unacceptable," he added.
Chu highlighted concerns that Microsoft has also begun to put restrictive terms on the use of VMs. Specifically, Microsoft is starting to restrict use of its VMs to Microsoft's Virtual Server and Virtual PC only. One such VM is the next release of Microsoft's development tool Visual Studio, codenamed Orcas.
In contrast, Chu noted, there are over 300 virtual appliances available on VMware Technology Network, ranging from Oracle databases to CRM (customer relationship management) packages to firewalls to e-mail security products to operating systems, that are "freely downloadable and usable by any user regardless of platform or product".
Microsoft said it supports products within its Virtual platforms such as Virtual PC and Virtual Server, because they are optimized for the Windows environment. But there is "no reason someone can't create a third-party virtual image of Visual Studio using our installation guides", the company noted.
Jim Lenox, general manager of VMware Asia South, noted during a media briefing Wednesday that standardization of VM disk formats will allow greater choice for users, and spur innovation among partners that develop virtual appliances.
In April this year, VMware announced that it was making its VM disk format, VMDK, available and free for anyone who wanted to use it. Since then, over 2,000 vendors and developers have requested to review and use VMware's VMDK specification, according to Chu.
Although Microsoft's recent evaluation of VMs for Exchange, SQL Server, and Windows Server can run on VMware products, "it is still troubling to see language from Microsoft that seemingly restricts [VM] usage to only Microsoft products," Chu said.
"Customers and partners have been very clear that a closed system based on licensing restrictions, that locks customers into one vendor's products and formats is not acceptable, and we look forward to Microsoft changing its published guidelines," he added.