Microsoft's Server Virtualization Roadmap

Microsoft's plans for virtualization technologies are in a state of flux, but company officials have been very clear that they're searching for ways to bring the technologies close to the core of Microsoft's infrastructure software stack.

With the virtualization software it bought two years ago from market also-ran Connectix, Microsoft trails VMware in capabilities and market share. Still Microsoft enjoys its usual advantage -- the ability to take relatively niche technologies and blast them into the mainstream by plugging them into Windows.

In a speech earlier this year, Microsoft CEO Steve Ballmer staked out a position that virtualization belongs in the operating system. "All operating systems have essentially been in the business to some degree in some way, shape and form of virtualization for all time. That's how operating systems grew up. Windows grew up virtualizing the screen, the printers, et cetera; so virtualization in a sense is not a new concept," Ballmer said at the Microsoft Management Summit in April. Ballmer is not alone in this view. Red Hat and Novell are both planning to bring virtualization into their Linux distributions.

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At the same time, Microsoft's virtualization-related message is changing from the Windows NT 4.0 migration and server consolidation gospel heard prior to the release of Virtual Server 2005 last year to a push for dynamic infrastructure. Microsoft is beginning to talk about virtualization's potential in terms of on-demand computing workloads in the same way that VMware has been talking about the technology for several years.

Earlier this summer, Bob Muglia, senior vice president for the Windows Server Division, put virtualization squarely inside Microsoft's Dynamic Systems Initiative (DSI), where: "We’re moving into a world where workloads are going to be moved dynamically across different machines." He added, "Another important component of DSI is a transition to virtualization as a more standard element in IT."

While the vision is clear, the precise roadmap remains murky and quite far off, subjecting it to all the vagaries of long-range Microsoft schedules. In the month-and-a-half between Ballmer's and Muglia's comments, the roadmap became a lot more specific, but it remains extremely loose.

The most solid thing on Microsoft's virtualization roadmap is Virtual Server 2005 Service Pack 1. Out in beta for months, SP1 is supposed to be released in final form before the end of the year. It goes part of the way to addressing some of Virtual Server 2005's most obvious shortcomings. One was the lack of Linux support. "We've added support for non-Windows virtual machines being hosted on top of our Virtual Server product, including support for Linux," Ballmer said. "We know folks are going to want to run Windows systems and Linux systems and other systems together on top of our Virtual Server and Windows."

The other major issue with Virtual Server 2005 was overhead. Like VMware's GSX Server, Microsoft Virtual Server requires a host operating system -- specifically a Windows server. Guest operating systems run on top of the host operating system, which runs the virtualization stack and handles resource virtualization and allocation. VMware moved beyond that model in 2001 with the release of ESX Server, a thin layer of software that runs directly on the hardware and handles virtualization tasks, but it will take Microsoft several years to get to the same place. For now, Microsoft's solution with SP1 is to support x64 hardware, which is supposed to offer such a scalability increase that the overhead won't be noticeable.

Another Microsoft virtualization element already in place is a management pack to allow management of the Virtual Server from Microsoft Operations Manager. A partner, Vintela, is working on a management pack to allow MOM administrators to manage Linux-based virtual machines within the Virtual Server 2005 SP1 environment.

The next generation is where things get interesting, and the roadmap gets fuzzy. Ballmer introduced a concept called hypervisors in April. Much like VMware's ESX Server, the hypervisor won't require a host operating system. In fact, Microsoft appears to be building the hypervisor atop another pre-release technology -- the Next Generation Secure Computing Base (NGSCB). The hypervisor would be Microsoft's place to support the virtualization technologies Intel and AMD are building into their processor platforms, as well. To complement the hypervisor and keep it thin, the Longhorn operating system would take on some virtualization services that would be available to the hypervisor. The approach confirms that Microsoft's virtualization approach would never be as platform independent as VMware's, as if that were in question. It would appear that at least one of the guest operating systems on a virtualized system would have to be running Longhorn server.

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With two pre-release technologies dependent on one another, Microsoft is not talking about bringing forward hypervisor virtualization in the Longhorn client (late 2006) or even the Longhorn server (2007). Instead, Microsoft officials talk about a Longhorn Wave. In an interview with Computerworld, Muglia suggested the hypervisor might make a first appearance in 2008 or 2009 as part of a Longhorn server service pack or Release 2 version.

In that same timeframe, Virtual Server is likely to drop away as a distinct product, as all of its functionality gets pulled into the hypervisor and base operating system. At the same time, Muglia speculated that Microsoft may release another product in the System Center family that handles virtualization management. Currently there is no piece of Microsoft software that can enable the movement of a virtual session from one physical machine to another. That kind of capability is key for the dynamic system management scenarios Microsoft hopes to enable in the next few years.

For now, EMC Corp.'s VMware has a clear lead over Microsoft, and customers looking for virtualization solutions today and into the next few years have a lot more flexibility from the current market leader. Even in the future, the type of vendor neutral platform VMware offers will have to be the choice of customers with little in the way of Microsoft server software. Nonetheless, Microsoft executives are saying the right things to be taken seriously as virtualization technology providers. While their roadmap is heavy on future deliverables, the company is improving the technologies it has today. Longer term, Microsoft may end up holding the stronger technology hand for one reason: Focusing resources on general virtualization development may prove to be more strategic for an operating system company than for a storage company.