Microsoft Slashes 'Viridian' Features to Meet Ship Date

Published: May 16, 2007

by Alex Woodie

Microsoft made the tough call last week when it announced it would be removing some features from its forthcoming hypervisor, codenamed "Viridian," in order to meet its previously scheduled ship date. Faced with a tight timeline and trouble meeting performance and scalability milestones, Microsoft decided to dramatically scale back Viridian's features so it could get the virtualization technology to Windows Server 2008 users on time, rather than shipping it late.

Indications started trickling in a month ago that something was amiss in Viridian-land. In mid-April, Microsoft announced it would not deliver the first public beta of the new technology during the first half of the year, as previously planned, and that instead the first beta would have to wait until the second half of the year. That put the first public beta of Viridian into the same six-month window that Microsoft committed to shipping "Longhorn," which Microsoft yesterday announced will be called Windows Server 2008.

With trouble already brewing in the Viridian lab and the project's timeline condensing, the crunch was really on to deliver a whole-hog, feature-complete version of Viridian, which Microsoft had boasted (perhaps a little too strongly) would do things no other hypervisor has been able to do. Microsoft had committed to delivering the Windows Server Virtualization technology within 180 days of the delivery of Longhorn, and had fiercely defended that plan against reports it planned otherwise. Not surprisingly, something had to give, and instead of delaying Viridian--a key Longhorn deliverable in lieu of Windows File System (WinFS), which was cut two-and-a-half years ago to keep Longhorn from further delays--the company decided to do the next best thing: start slashing the features.

Microsoft has cut three key features from Viridian, including support for live migration; support for hot-add of storage, networking, memory, and processor resources; and support for 64-core systems. Instead, Viridian will support only 16 cores, or logical processors, putting the product on par with the rest of the virtualization industry.

Even as Microsoft was delaying the first public beta of Viridian in April, the company was still beating its chest over Viridian's planned features. "We're designing Windows Server virtualization to scale up to 64 processors, which I'm proud to say is something no other vendor's product supports," Mike Neil, general manager of Microsoft's virtualization strategy, wrote in the Windows Server Division Blog last month. "We are also providing a much more dynamic VM [virtual machine] environment with hot-add of processors, memory, disk, and networking as well a greater scalability with more SMP [symmetric multi-processor] support and memory."

As it turns out, Microsoft is not going to lead the industry in any of those areas, at least not off the bat.

"But with all this progress comes the occasional tradeoff," Neil wrote on the Windows Server Division Blog last week. "Earlier this week we had to come to grips with some universal truths about product development [that] shipping is a feature, too; [that] the quality bar, the time you have, and the feature set are directly correlated; [and that] . . . resources are not infinite and even if you could add more it does not help get more done faster.

"So we had some really tough decisions to make," Neil continues. "We adjusted the feature set of Windows Server virtualization so that we can deliver a compelling solution for core virtualization scenarios while holding true to desired timelines."

To be sure, developing a hypervisor is not easy. Enabling the "hot add" of resources is a difficult task, but one that Microsoft's virtualization competitors, including VMware, can pull off. The difficulty level is one of the reasons why Microsoft has tapped XenSource, developer of the Xen hypervisor and an eventual competitor to Viridian, to assist with the development of Viridian.

Viridian will be a very important element of Windows Server at some point in time. Hypervisors already play key roles in server consolidation, high availability and disaster recovery, and test and development scenarios, and that role will only get bigger as mainstream virtualization technologies like Viridian are brought to market. The tough lessons Microsoft is learning now can only help Windows shops looking to adopt virtualization into their environments down the road. That road is just a little bit farther off now.

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'Viridian' Beta Delayed. Is Longhorn Next?

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Microsoft Unveils "Viridian" Hypervisor, Extends Virtualization Roadmap

Microsoft Cuts WinFS from Longhorn to Make 2006 Ship Date

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