The charges are unusual in that the two companies both acknowledge they are partners and have worked together on virtualization issues in the past.
Is VMware crying "wolf" when it's not clear to customers whether the wolf is really at their door? Or is VMware trying to avoid the fate of browser supplier Netscape and protest before what is now an independent class of software gets swallowed up by the operating system?
VMware charges Microsoft won't support Windows or its applications when they are running in a third party virtual machine, unless the customer has purchased its Premier support. If Microsoft can support its Premier customers, says VMware in the white paper, "there is no technical reason to deny the same to all customers" with lower level support contracts.
Microsoft's Mike Neil, general manager of virtualization strategy, says Microsoft's policies on its virtualization products "are progressive and fair... creating a level playing field for partners and customers." The requirement for Premier support for virtualization users is part of Microsoft's commitment "to providing high-quality technical support," said Neil in a message to Information Week.
Microsoft published its Virtual Hard Disk format in 2006 and vowed to keep it open under its Open Specification Promise. The move allowed users to format a copy of the Windows operating system and application as a single virtual file, in effect, creating a combination ready to run in a virtual machine.
VMware says Microsoft restricts running "some" of these VHD-formatted files in any virtual machine but its own. The virtual machine files are "configured to deactivate themselves if they find they are not running inside Microsoft's Virtual Server or Virtual PC products, the white paper says.
Neil didn't directly address this charge in his responses to the VMware white paper. But in a Feb. 25 blog on the Microsoft site, he noted that Microsoft has opted to work closely with XenSource, the commercial company behind the open source Xen virtual machine, to guarantee that Linux, as well as Windows, will run in virtual machines on Windows Server in the upcoming Longhorn version.
VMware says it does not restrict in what brand of virtual machines its Virtual Machine Disk format may run.
VMware's Srinivas Krishnamurti, director of product management, said in an interview that VMware's charges come down to Microsoft generating barriers to customers adopting VMware products during a period in which VMware has a clear lead in the marketplace.
With enough restrictions, virtualization users won't adopt VMware's Virtual Center for managing multiple virtual machines or VMotion for migrating running virtual machines from one physical server to another. It's keeping as many users as possible out of the VMware camp until it can bring new virtualization features to bear in Windows Longhorn Server. "That seems like their strategy," Krishnamurti said.
Neil spent a good part of his blog ignoring VMware's charges and emphasizing upcoming features in Viridian, the virtualization facility that will be part of Windows Longhorn Server and pull Microsoft into closer alignment with what VMware now offers. It will offer "live migration" of virtual machines between servers and make Windows "the most manageable virtualization platform," he wrote.
Charles King, analyst at Pund-IT, Inc., commented on the exchange: "Microsoft is simply doing what most any company would do in similar circumstances: protecting hard won turf and stymieing competitors in every way imaginable."