Microsoft Competing Unfairly on Virtualization, VMware Says

Published: March 6, 2007

by Alex Woodie

Microsoft is leveraging its dominant market position to restrict Windows users from using non-Microsoft virtualization software, VMware claims in a new white paper posted to its Web site last week. According to VMware--still the dominant vendor in the nascent virtualization market--instead of competing fairly, the software giant is using licensing to restrict customer choice and to steer the industry toward its own virtualization specifications and APIs. Microsoft denies the claim, and says it's working in the best interest of its customers.

In its seven-point complaint, VMware posits that Microsoft recently made changes to its licensing policies that restricts how customers can use Microsoft products in virtualized environments. It also claims Microsoft is unfairly favoring its own virtualization products through restrictive licensing and keeping a close lid on APIs, an accusation that Microsoft denies.

"Microsoft is not acting in customers' best interests when they attempt to force an integrated virtual hardware/operating system/application stack for their operating system and applications," VMware says its in white paper, which can be viewed here. "Customers require an 'any to any' interoperability model where Microsoft application stacks can run freely with licensing, open APIs, and support equivalence on non-Microsoft virtual hardware to Microsoft's own virtualization technologies."

Specifically, VMware points to changes Microsoft has made to how it licenses its Virtual Hard Disk (VHD) spec, a key technology that enables entire OS images to be easily distributed as a single file. Last October, Microsoft committed to distributing the VHD spec via its Open Specification Promise (OSP), a relatively new licensing scheme in which Microsoft promises not to sue those who adopt products or technology distributed under the OSP license.

According to VMware, Microsoft's VHD licensing also restricts virtual machines formatted with the VHD spec to running only in Microsoft's virtualization products, including Virtual Server and Virtual PC. VMware also claims any attempts to open and run virtual machines formatted with the VHD spec on third-party virtualization products, such as VMware's ESX Server, will cause the VHD-formatted virtual machines to deactivate themselves. Users are also prevented from moving VHD-formatted virtual machines into virtual machines based on other virtualization technologies, the company claims.

VMware wasn't happy with the inclusion of VHD into the OSP back in October, and it's not any more pleased about it now. VMware sells its own competitive virtual machine format, called Virtual Machine Disk Format (VMDK), which it claims is adopted by more than 2,000 technology partners, including Oracle and Red Hat. Microsoft also has substantial industry backing from players like Fujitsu and virtualization software developer XenSource, which is working with Microsoft on the development of the new "Viridian" hypervisor layer that will debut with Windows Server "Longhorn," expected to debut later this year.

Viridian is another bone of contention between VMware and Microsoft. VMware claims Microsoft is not sharing the APIs for Viridian with other virtualization software developers, such as itself. "Microsoft disclosed these API specifications at the WinHEC conference in June 2006, but is not permitting use of these APIs by other virtualization vendors," the company claims.

Mike Neil, Microsoft's virtualization program manager, acknowledges that Microsoft isn't sharing APIs for products that aren't yet commercially available--a list that includes the Viridian hypervisor. But he maintains that Microsoft is open to working with others in the industry to serve customers' best interests.

"To encourage interoperability," he says, "we openly share technology and have published a set of APIs for all our commercially available virtualization products today and provided documentation on APIs for the hypervisor that will be part of the next version of Windows Server, codenamed Longhorn."

VMware also says Microsoft unnecessarily restricts users from moving their virtual machines from server to server, which is necessary for disaster recovery and network load balancing, and is one of the primary benefits of virtualization software, VMware claims. Again, the company points to Microsoft's licensing terms, which prevents volume license customers from moving server-based products from one machine (either virtual or physical) more than twice in any 90-day period. VMware says it's a blatant attempt to get customers to buy more copies of Windows Server.

Microsoft is also using virtualization to squeeze more money out of Vista users, VMware claims. Microsoft only allows the most expensive versions of Vista, such as Vista Business and Vista Ultimate, to run in a virtualized environment. Windows Vista Home Basic and Home Premium cannot be run in virtualized environments. Microsoft's rationale is that only higher-end customers (or those most likely to have qualified technical support) are skilled enough to deal with the security threats that running Windows Vista in virtualized environments exposes.

VMware isn't buying this rationale. "This contention stands in contrast to the several million users of software like VMware Workstation and VMware Player who have adopted virtualization for their general purpose desktop . . . ," VMware says in its document.

Microsoft hasn't done anything untoward in its virtualization licensing, according to Neil. "Virtualization has long been a core part of server operating systems and this dynamic market is enjoying a fresh round of innovation," he says. " Microsoft believes the best approach for customers lies in establishing a foundation of cooperation between vendors, which is why we strive to regard virtual machines and virtualization technology the same way. Windows server licensing offers a level playing field to all."

As the issue escalated last Tuesday, Microsoft released this additional statement from Neil: "Microsoft believes the claims made in VMware's white paper contain several inaccuracies and misunderstandings of our current license and use policies, our support policy, and our commitment to technology collaboration," he says. "We believe it's better to resolve VMware's claims between our two companies so that we can better serve customers and the industry. EMC is a long-time partner of Microsoft. We've extended this courtesy to VMware . . . We are committed to continuing to collaborate with VMware."

More explanations from Neil on Microsoft's stance on virtualization can be found at the Windows Server Division blog and the Windows virtualization team blog.

VMware's attack on Microsoft's virtualization strategy comes at a curious time, considering VMware's current dominance of the market for virtualization software. The company, which is a subsidiary of EMC, has been so successful that EMC is planning to spin-off VMware into its own company with an initial public offering (IPO) of stock, rekindling the hopes of a new technology bull rush on stock market.

In the middle of these two extremes lies VMware, which seeks to give companies the freedom of movement among their proprietary stacks, while supporting open standards and cooperation with other vendors along the way. That is why the partnership between XenSource and Microsoft poses such a threat to VMware, because it has been outflanked on both sides. VMware is the 800-pound gorilla at the moment, but only time will tell if VMware can maintain its leadership position against Microsoft's market power and unlimited resources.

RELATED STORIES

XenSource, Virtual Iron Gun for VMware with Features, Low Prices

Microsoft to Distribute VHD Spec Under New OSP License

Microsoft Taps Xen to Help Build Longhorn's Hypervisor

Microsoft Unveils "Viridian" Hypervisor, Extends Virtualization Roadmap

                     Post this story to del.icio.us
               Post this story to Digg
    Post this story to Slashdot