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Hyper-V SP1 increases support for VMs/core for Windows 7

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Awesome news, hot off the press. We have just completed a new round of testing for Windows Server 2008 R2 SP1 with Hyper-V and Dynamic Memory. What showed was that Hyper-V SP1 could scale a lot more with Windows 7 SP1 than we were actually supporting previously with 8 VMs/core. I should be clear here though. We dont really support VMs/core...we actually support VMs/logical proc. The new support limit is 12VMs/Logical Processor. Whats the difference?

VMs/core support implies only physical core support. Logical processors can be either physical or multi threaded cores. As an example, Intels newest Westmere processors support 6 cores, though they are Hyperthreaded, meaning that you actually have 12 logical processors. According to our new support statement this means that on just one of these Westmere processors, we can support up to 144 VMs! Of course this depends on the workload in use but it definitely lifts the game in support.

Watch out also for a whitepaper in process on Hyper-V coming soon, that will highlight some of the testing I referenced in my post on the Virtualization blog. In fact if you want to see me presenting on this, youre welcome to view the session I did at TechEd Europe on how we scaled 40% higher in density with Hyper-V SP1 and Windows 7

Comments

  • Anonymous
    January 07, 2011
    Michael, wasn't the support limit (and hard limit) previously based on the number of vCPUs per core? So a quad core CPU (no HyperThreading) could support 32 virtual CPUs, not necessarily 32 guests? In that case the Westmere (6+HT) CPUs can support 144 virtual CPUs each:
  • 144 single vCPU guests
  • 72 dual vCPU guests
  • 36 quad vCPU guests
  • A mixture of the above specs, with the total number of running vCPUs being less than 144 (12 x host Logical CPUs)