Which two steps can be taken to resolve this issue?

An administrator is migrating a virtual machine in a DRS cluster. The migration fails the validation check because of a CPU incompatibility issue.

Which two steps can be taken to resolve this issue? (Choose two)

A.
Identify the CPU feature incompatibility, and then disable the feature in the BIOS of the effected ESXi hosts.

B.
Configure EVC for RDS (DRS?) cluster.

C.
Configure EVC for each ESXi host.

D.
Identify the CPU feature incompatibility, and then mask the feature on all virtual machines in the cluster.

Explanation:
CPU Compatibility and EVC
vCenter Server performs a number of compatibility checks before allowing migration of running or suspended virtual machines to ensure that the virtual machine is compatible with the target host. vMotion transfers the running state of a virtual machine between underlying ESXi systems. Successful live migration requires that the processors of the target host be able to provide the same instructions to the virtual machine after migration that the processors of the source host provided before migration. Clock speed, cache size, and number of cores can differ between source and target processors, but the processors must come from the same vendor class (AMD or Intel) to be vMotion compatible.

Migrations of suspended virtual machines also require that the virtual machine be able to resume execution on the target host using equivalent instructions.
When you initiate a migration with vMotion or a migration of a suspended virtual machine, the Migrate Virtual Machine wizard checks the destination host for compatibility and produces an error message if there are compatibility problems that will prevent migration.

The CPU instruction set available to the operating system and applications running in a virtual machine is determined at the time that a virtual machine is powered on. This CPU "feature set" is determined based on the following items:

* Host CPU family and model
* Settings in the BIOS that might disable CPU features
* The ESX/ESXi version running on the host
* The virtual machine’s virtual hardware version
* The virtual machine’s guest operating system

To improve CPU compatibility between hosts of varying CPU feature sets, some host CPU features can be "hidden" from the virtual machine by placing the host in an Enhanced vMotion Compatibility (EVC) cluster.

4 Comments on “Which two steps can be taken to resolve this issue?

  1. Anitha says:

    Correct answer should be B and D

    To improve CPU compatibility between hosts of varying CPU feature sets, some host CPU features can be “hidden” from the virtual machine by placing the host in an Enhanced vMotion Compatibility (EVC) cluster.

  2. Anitha says:

    option A is definetly incorrect

    Hardware vendors sometimes disable particular CPU features in the BIOS by default. This can cause problems in enabling EVC, because the EVC compatibility checks detect the absence of features that are expected to be present for a particular CPU. If you cannot enable EVC on a system with a compatible processor, ensure that all features are enabled in the BIOS.

  3. Teesh Ali says:

    Answer is B & D


    Enhanced vMotion Compatibility (EVC) – You can use EVC to help ensure vMotion compatibility for the hosts in a cluster. EVC ensures that all hosts in a cluster present the same CPU feature set to virtual machines, even if the actual CPUs on the hosts differ. This prevents migrations with vMotion from failing due to incompatible CPUs.
    Configure EVC from the Cluster Settings dialog box. The hosts in a cluster must meet certain requirements for the cluster to use EVC. For information about EVC and EVC requirements, see the VMware vSphere Datacenter Administration Guide.

    CPU compatibility masks – vCenter Server compares the CPU features available to a virtual machine with the CPU features of the destination host to determine whether to allow or disallow migrations with vMotion. By applying CPU compatibility masks to individual virtual machines, you can hide certain CPU features from the virtual machine and potentially prevent migrations with vMotion from failing due to incompatible CPUs.

    source: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003212


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