Earlier today, Rick Vanover discussed a major improvement to clustering in Windows Server 2008 R2, particularly as it pertains to supporting migration in Hyper-V R2. This improvement is just one of a ton of enhancements coming to the Hyper-V platform when Hyper-V R2 hits the streets. In this post, you’ll learn about some other offerings shipping with Hyper-V R2 that will go a long way toward helping the platform achieve viability for a larger number of organizations.

First of all, Hyper-V R2 will be capable of supporting 384 single virtual processor virtual machines on a single server. Assuming that you can get the RAM and processing power necessary to reasonably support that many virtual machines on one server, that’s a pretty densely packed machine! To achieve a high-density goal, Hyper-V R2 supports up to 512 virtual processors in a single host server, allowing up to 384 single virtual processors, 256 dual virtual processors, or 128 quad virtual processors — or any combination that doesn’t exceed a maximum of 512 virtual processors. VMware ESX 3.5 supports 170 virtual machines per physical host with up to 192 virtual CPUs per server. VMware vSphere increases the number of virtual machines and virtual CPUs per physical host to 256.

What does this mean for you? Probably not a whole lot right now since not too many people run production server farms with these kinds of densities, but it does indicate that Microsoft is working hard to make Hyper-V scalable at a very high level. Think mainframe size loads.

Perhaps the coolest new feature coming in Hyper-V R2 is Processor Compatibility, which allows the migration of virtual machines between host servers with different processors. That is, a machine can be migrated from one server running brand new Nehalem/Xeon 5500 series processors to a host containing, for example, Core 2 Duo or Xeon 5400 series processors, among other Intel-based processor families. Processor Compatibility will not allow you to migrate virtual machines between Intel and AMD hosts; you must stay within the same processor family.

In short, Processor Compatibility works by supporting only the feature set of the lowest common denominator processor family, even when the VM runs on a processor that supports a wider feature set. Processor Compatibility is handled on a per-VM basis, allowing you a great deal of granular control over which machines will use this feature.

It’s important to note that VMware’s vSphere (actually, ESX 3.5 with Update 2) product also supports this type of migration. Called Enhanced VMotion Compatibility, VMware-based virtual machines can be migrated between machines with different processor types too (check out this very cool YouTube video of a live migration demo). The primary difference between Hyper-V and ESX is in the way that the cross-platform migration is achieved. While ESX uses hardware methods built into processors, AMD uses what’s called Extended Migration, and Intel uses what’s called FlexMigration; Microsoft uses a software approach.

Although Microsoft has been seriously late to the enterprise virtualization game, it’s obvious that the company is working to make up for lost time.

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