Pentacore CPUs in VMware ESX 4

You have probably heard that in VMware vSphere 4, ESX now supports up to 8 virtual CPUs per virtual machine.  A related change that hasn’t gotten much attention is the fact that ESX no longer requires the number of vCPUs in a VM to be a power of two — 2, 4, 8.

That means you don’t have to go for a full 8 vCPUs if your workload would not benefit from it.  You might choose to run 5 vCPUs:

Five vCPUs on a Windows 2003 VM.

The VM CPU configuration dialog now looks like this:

VMware ESX 4 now allows selecting any number of CPUs.

Will you deploy VMs with 3, 5, 6, or 7 vCPUs?

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  1. Erik’s avatar

    I’ll use VM with 3 vCPU when I want to software emulate a Sony PS3 😉

  2. craig’s avatar

    this features is good for the administrator to control the number of vcpu per VM, only add when it need 🙂

  3. Alejandro’s avatar

    Yes, I’ll use more than 2 Cpu for Real Time Video Transcoding… but currently has ESXi 3.5 and this not a feature for me 🙁

  4. milo’s avatar

    How many nic’s can i use with vsphere? is the maximum 4, like in the old version?

    1. Eric Gray’s avatar

      Milo, vSphere allows 10 NICs in a VM. Check out this article that discusses the vSphere configuration maximums document.

    2. Randy’s avatar

      This is quite useful when you want a lot of cores on your VM, but don’t want to oversubscribe. It is not recommended to run a VM with 4 cores on a host with 4 cores, since 1 core is usually needed for running VMkernel and other processes. So you can create a VM with 3 cores and get the best performance. Likewise, you can create a 7 core VM on a host with 8 cores.

      Although you can certainly do 4-on-4 or 8-on-8 it is generally not recommended due to co-scheduling concerns.

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