Acropolis Hypervisor (AHV) & non-uniform node CPU generations

For those of you familiar with VMware vSphere’s Enhanced vMotion Compatibility (EVC) feature, you might be wondering how non-uniform CPU generations are handled in an Acropolis Hypervisor (AHV) environment.

Well, as with most things Nutanix, the answer is simple.

NOS 4.5 automatically detects and configures the lowest common CPU generation as the baseline on a per cluster basis.

The following diagram shows how it works:


As we can see, we have a four node Acropolis cluster with 3 different CPU generations. Acropolis detects Sandy Bridge as the lowest common denominator and ensures VMs on all nodes are only exposed the Sandy Bridge CPU capabilities.

This ensures Live migration capabilities are maintained across the cluster.

Note: As with vSphere’s EVC, VMs still benefit from higher clock rates and performance from newer generation CPUs, they just don’t have all CPU capabilities¬†exposed, so don’t be fooled into thinking your newer/faster CPUs are wasted in a mixed environment.

2 thoughts on “Acropolis Hypervisor (AHV) & non-uniform node CPU generations

  1. Hi Josh,
    How does the acropolis cluster deal with the scenario you described, where you retire the older nodes and introduce newer haswell CPUs across the cluster? What needs to happen to lift the CPU mask to be haswell? I am guessing there would be reboots required like vSphere to allow the VMs to detect the new mask?

    • Similar to vSphere the running VMs do need to power off/on to take advantage of the newer cpu instruction sets but powered off or new VMs powering on would have access to all CPU instruction sets straight away.

      Let me know if you have any other questions, also keep across it with Darryl as he’ll be a great source of information for you.