Knowledge Base

This issue is seen with Enhanced VMotion Compatibility (EVC) clusters where the ESX Host CPU Model is Intel 3500 series or 5500 series (Nehalem).

The problem occurs if ESX 3.5 Update 4 or later and vCenter Server 2.5 Update 4 or later are not installed.

1. As per the VMware Compatibility Guide ensure that any ESX in the EVC cluster with a Nehalem CPU has ESX 3.5 Update 4 or later installed.
   
   Note: ESX hosts in the cluster that do not have a Nehalem CPU do not need to be upgraded to ESX 3.5 Update 4. However, they must meet the minimum requirements to support EVC as detailed in Enhanced VMotion Compatibility (EVC) processor support (1003212) .
   
   
2. Ensure that vCenter Server 2.5 Update 4 or later is installed.
   
   
3. If, having completed the steps above there are still problems with VMotion, ensure that no CPUID masks are applied to the virtual machines. If CPUID masks have been applied, reset the masks to the default:
   
   
   1. Power down the virtual machine.
   2. Right-click on the virtual machine and choose Edit Settings.
   3. Click the Options tab.
   4. Select CPUID Mask under Advanced.
   5. Click Advanced.
   6. Click Reset All to Default.
   7. Click OK.
   8. Click OK.
   9. Power on the virtual machine and migrate.