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Microsoft Maps Out Plan to Integrate Virtualization into Windows

Over the next few years, Microsoft intends to phase out the virtualization products it acquired from Connectix Corp. and develop virtualization functionality of its own in the heart of the Windows operating system.

In an online customer chat last month with Bob Muglia, senior vice president of the Windows Server Division, Microsoft offered much more detail than ever before about how it plans to integrate virtualization technology directly within Windows.

Redmond's current virtualization product lineup consists of Virtual PC 2004 and Virtual Server 2005 (as well as Virtual PC for Mac). Eventually, Microsoft wants to put virtualization into the operating system via a virtualization stack and a thin software layer called the hypervisor. Microsoft describes the hypervisor as code that sits at the lowest level of the host OS to abstract and control hardware access for multiple guest operating systems.

The first move, announced in late August, will be to eliminate Virtual Server 2005 Service Pack 1, which has been in beta testing since April. Microsoft decided belatedly that SP1 had too much new functionality to be given away for free to anyone except customers already paying for Software Assurance. Renamed Virtual Server 2005 R2, the product is scheduled for a mid-Q4 release to manufacturing (RTM). There are no plans to update the beta code released as SP1 before R2's RTM. With no major security issues plaguing Virtual Server 2005, Microsoft has no plans to deliver a bug fix-only SP1 now either.

Support for Linux guest operating systems is the most notable new feature coming in Virtual Server 2005 R2. Other new features will include:

  • Support for x64 versions of Windows Server 2003 and Windows XP as hosts to allow more virtual machines per host
  • Performance enhancements like improved hyper-threading (performance improvements will be best on guest process switching and memory-intensive applications)
  • Built-in support for network installations of guest operating systems
  • Higher availability through support for failover clustering across hosts

Next Step
Microsoft intends to quickly follow the R2 release with another release of Virtual Server. The as-yet-unnamed, post-R2 version of Virtual Server is supposed to enter beta testing in the first half of 2006 and RTM in the second half. It will support the hardware-level virtualization platforms being developed by Intel and AMD. Both Intel, via VT or "Vanderpool," and AMD, with "Pacifica," are working to make their chips more adept at simultaneously running multiple operating systems. The post-R2 Virtual Server beta release should coincide with the initial availability of server chips from those companies sporting the new virtualization architectures.

In the user interface, R2 will bring only minor changes to the process of creating VMs and for branding. According to Mike Neil, product unit manager for virtualization, Microsoft is also considering adding support for snapshot backups of virtual machines in the post-R2 version.

On the client side, Virtual PC 2004 will go through another rev before hypervisors make their way into the Windows client. "We are planning an upgrade for next year that will have performance improvements," Neil said during the chat in response to a question complaining about the speed of the product versus competitors. "We have plans for an update to [Virtual PC] around Windows Vista that will provide improved performance as well as 64-bit host support. Look for more details on this toward the end of the year."

Microsoft repeatedly answered requests for features during the customer chat by promising support in Windows virtualization, which will not arrive for some time. "[Hypervisor support in Longhorn] will ship after Longhorn Server," Muglia said. Longhorn Server is promised for 2007. "The server implementation will come first as there are additional things which need to be done on the client." Microsoft plans to deliver support in an R2 version, a service pack or an update of Longhorn Server. With the client piece so far out, there's been no decision on whether it would be an upgrade for Windows Vista or whether it will ship with some other client operating system.

As if there were any doubt, Microsoft is not working on any VMware ESX-style virtualization software that requires a no host operating system (read no Windows). "The future of virtualization is in thin hypervisors with a virtualization stack built into the OS. That is what we're doing," Muglia said.

The frequently requested features that Windows virtualization will support include:

  • A completely revamped UI
  • Support for 64-bit guest operating systems
  • Support for SMP guests
  • Remote Desktop/Remote Desktop Protocol UI integration
  • Published interfaces to let developers of other operating systems plug into the Windows infrastructure
  • Copy-and-paste support and improvements in I/O performance

The SMP guest issue is one of the most interesting features. Virtual Server currently scales across multi-processor servers up to 32 processors. No individual virtual machine, however, is allocated more than a single processor. Running Virtual Server on large SMP systems lets users run more virtual machines, not larger ones. With Windows virtualization, Microsoft expects to create virtual machines on guest operating systems encompassing several processors.

At the same time, Virtual Server currently runs on dual-core processors, but doesn't recognize or use the second processor core. Microsoft aims to change that when it brings virtualization into Windows.

Along with the effort to shift from virtualization products to hypervisors and virtualization stacks within Windows, Microsoft is working on improving virtualization management technologies within the System Center product family. "We are building management tools to allow the placement of VMs and migration. We're also enhancing [Systems Management Server] and [Microsoft Operations Manager] to treat VMs as a core part of Windows," Muglia said.

Microsoft clearly has many balls in the air regarding virtualization. The change coming in Virtual Server 2005 R2 to support Linux guest operating systems is an important fix for enterprise customers with heterogeneous environments. At the same time, the recent chat highlighted a number of customer concerns, especially about I/O performance and feature parity with VMware in the SMP guest area. Microsoft's design decision to focus development efforts on bundling virtualization into Windows means many of those issues will have to linger for another three to five years.

About the Author

Scott Bekker is editor in chief of Redmond Channel Partner magazine.

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