Archive for the ‘EVC’ Category


We wanted to enable VMware EVC on our cluster (cluster 1) but we couldn’t enable the EVC , because in order to be able to enable EVC – all virtual machines must be powered off , and our vCenter server as a virtual machine, was standing in our way.


  • Take one ESX server from cluster 1 and insert it into maintenance mode.
  • Remove ESX server from cluster 1 .
  • Create a new cluster (cluster 2)
  • Add the ESX server which you have just removed from cluster 1 to cluster 2 (make sure not to change anything in the storage configuration in that ESX server – the ESX server has access to the old cluster LUNs)
  • Use Live migration (vMotion) in order to migrate vCenter server from cluster 1 to cluster 2


  • Power off all virtual machines in cluster 1.
  • Enable EVC on cluster 1 ( stand on the cluster > Edit Settings > VMware EVC > Change > Enable EVC for Intel Hosts)



  • Connect using the vSphere client directly to the ESX host in cluster 2.
    • Stand on vCenter Server virtual machine.
    • Right click > Edit Settings > Options > General Options > Virtual Machine Configuration File.
    • Write down the full path of the vCenter server virtual machine.
  • Connect using SSH to the ESX host in cluster 2.
    • Navigate to the vCenter path (which you’ve found out in the paragraph above)
    • Copy the full path (including *.vmx file).
    • From the SSH, power off vCenter server. Using the following command : vmware-cmd “Virtual_Mchine_Full_Path.vmx”  stop
    • In order to check if the vcenter server has powered off, run the following command: vmware-cmd “Virtual_Mchine_Full_Path.vmx” getstate
    • After you’ll see that the server is powered off , unregister the virtual machine from the ESX host in cluster 2 , using the following command:
      • vmware-cmd –s unregister “Virtual_Mchine_Full_Path.vmx”


  • Afterwards connect using SSH to another ESX server in cluster 1.
    • Register vCenter server in that ESX server using the following command:
      • vmware-cmd –s register “Virtual_Mchine_Full_Path.vmx”


    • Make sure that the vCenter server has successfully registered in the new ESX server, and is currently powered off using the following command:
      • vmware-cmd “Virtual_Mchine_Full_Path.vmx” getstate
    • Power on vCenter server virtual machine using the following command:
      • vmware-cmd “Virtual_Mchine_Full_Path.vmx” start
    • Answer vCenter server virtual machine’s question.
      • vmware-cmd “Virtual_Mchine_Full_Path.vmx” answer
    • Create a new identifier by choosing 0
  • Enter the ESX which exist in cluster 2 into maintenance mode.
  • Remove the ESX from the cluster.
  • Add the ESX server to cluster 1.
  • Delete cluster 2.

Fixed! You have just configured EVC in cluster 1, and returned vCenter server virtual machine back to that cluster 1.

If you like you can read about it in the following link:


Yaron & Idit.


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Enhanced VMotion Compatibility (EVC) simplifies VMotion compatibility issues across CPU generations. EVC automatically configures server CPUs with Intel FlexMigration or AMD-V Extended Migration technologies to be compatible with older servers. After EVC is enabled for a cluster in the VirtualCenter inventory, all hosts in that cluster are configured to present identical CPU features and ensure CPU compatibility for VMotion. The features presented by each host are determined by selecting a predefined EVC baseline. VirtualCenter does not permit the addition of hosts that cannot be automatically configured to be compatible with the EVC baseline.

Hardware Changes

In order to enable VMware EVC we must first change two parameters in the server’s BIOS:

1)      HP DL 380 G5

Please enter the BIOS and change the following:

In order to enter the BIOS please press F9 at startup.

  1. Advanced Options > Processor Options > No-Execute Memory Protection (Enabled)
  2. Advanced Options > Processor Options > Intel Virtualization Technology (Enabled)


2)      IBM x3550

Please enter the BIOS and change the following:

In order to enter the BIOS please press F1 at startup.

  1. Advanced Setup > CPU Options > Execute Disable Bit (Enabled)
  2. Advanced Setup > CPU Options > Intel Virtualization Technology (Enabled)



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