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Thoughts on the Windows Server Virtualization Announcement

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By now most readers of this blog will have heard that some of the planned Windows Server Virtualization (Viridian) features have been deferred. The details were posted here. Dan Kusnetzky over on ZDnet has a blog post with good analysis of the options. This was certainly a disappointment for those of us who are excited about the technology. Clearly some work needs to be done on the planning and expectation setting process. The bottom line in a situation like this is that this technology is complicated and sometimes issues crop up that are not possible to anticipate and sometimes take longer than expected to solve. This leads to the situation where you are behind schedule. At this point, as both the orginal post and Kusnetzky's post point out, in software dev you have three choices: Reduce quality and testing to ship on time; Push out the release date for the full product; Cut features and ship on schedule. You then need to make the decision as to which course to take and let your customers know as soon as possible. Given the state of the market, my view is that the team made the right decision.

The decision-making process for what to virtualize should revolve around the resources required by the workload to be virtualized (processor, ram, I/O, etc). Currently, Microsoft virtual machines are limited to a single processor core, just under 4 GB of RAM, and 4 NICs. Consequently, no single server workload that requires more than this can be virtualized without changes such as scaling it out to multiple VMs etc. Windows Server Virtualization is being designed to remove those limitations as a top priority. There are additional priorities such as high availability, dynamic data center scenarios, etc. The identification and prioritization of these scenarios is critical and customer driven as it should be.

Those priorities were planned to be accomplished in WSV via the following major features.

  1. Multi-Processor Virtual Machines
  2. Large Memory Support in Virtual Machines
  3. 64-bit Virtual Machines
  4. "Live Migration" or vMotion-like Functionality
  5. Hot Addition of Processors, RAM, NICs 

As you can see from the announcement, Live Migration and Hot Add are being deferred. That still leaves several major features (in addition to a lot of other features) still included in the initial release. The features that are in address the biggest limitation with our current offerings, namely the size of the single server workload that can be virtualized. The team in my view is correctly evaluating the market, our offerings, competitor's offerings, and customer needs. I certainly wish all five features would be in the first release but I also would certainly rather have the first three on schedule than to have to wait 3, 6, or more months to get any of them. Put simply, the cup is 3/5ths full...

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