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Modify number of CPUs in VM

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  • Modify number of CPUs in VM

    We P2V'd a server with 4 physical processors and it has only 2 virtual CPUs afterward. Can I increase the number of CPUs to 4 without issue as the VIC says the OS may become unstable if the number of CPUs is modified?

    We are using ESX 3.5 Update 6 and the virtual server is Windows 2003 Standard edition.

    Thanks for your assistance.

  • #2
    Re: Modify number of CPUs in VM

    Is the application or OS performance a problem with only 2 CPUs? Just because the OS had 4 CPUs available on the physical server doesn't mean it actually used them effectively. If you do need to increase the number of CPUs there shouldn't be a problem, Windows will already be using a multiprocessor kernel to access the 2 CPUs.
    VCP2 / VCP3 / VCP4 / VCP 5 / VCAP-DCA4 / VCI / vExpert 2010-2012


    • #3
      Re: Modify number of CPUs in VM

      The server is running IIS and one the Application Pools is periodically pegging the CPU utilization at between 80 and 100 percent until worker threads are released. I was thinking that increasing the CPUs back to 4 would alleviate the issue.

      Thanks for your response.


      • #4
        Re: Modify number of CPUs in VM

        should be fine. I've amended cpu settings before - obviously you nede to shut the guest down to do it.

        But - you've also got a fairly simple roll-back plan if it doesn't work.. simply remove the two additional processors..
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        • #5
          Re: Modify number of CPUs in VM

          the thing to remember is that Windows detects HW changes and may need to be re-activated.
          change only one HW setting at a time.
          increasing the CPU cores is no problem unless you change another setting, such as RAM and MAC address at the same time.
          Simply boot inbetween changes, that'll do