Posts Tagged ‘EVC’

VMware: EVC – Method not found: ‘Vmomi.HostSystemArray EVCState.get_BadSoftwareHostsBlockingEVC()’

January 7th, 2011 3 comments

Today I got an error when selecting the “VMware EVC” option in the Cluster Settings at my vCenter 4.0 host with multiple HP Blades with same CPU. Error message:

Method not found: ‘Vmomi.HostSystemArray EVCState.get_BadSoftwareHostsBlockingEVC()’



This issue occurs when a system installed with vSphere 4.1 and you use vSphere 4.0 Client on that system to access vCenter Server 4.0.

To workaround this issue, install a vSphere 4.0 Client on a system on which you have not installed vSphere4.1 Client earlier and then update the EVC cluster using the vSphere 4.0 Client.


Source: VMware


Sander Daems is founder and author of this blog and working as a Lead (Sr.) Consultant by UNICA ICT Solutions. Sander has over 15 years experience in IT, primary focus: virtualization and modern worksplace.

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VMware: VMotion CPU Compatibility Requirements for Intel Processors (1991)

June 8th, 2009 No comments

Why am I unable to migrate virtual machines with VMotion across Intel processors?

In ESX 3.5 Update 2 and later, VMware recommends using Enhanced VMotion Compatibility (EVC) to eliminate many VMotion CPU compatibility problems. For more information on EVC, see KB 1003212.
To ensure system stability during migration with VMotion, VirtualCenter and vCenter Server require the source and target CPUs to be compatible. For more information on CPU compatibility requirements, see Basic System Administration for your version of VirtualCenter or vCenter Server, available from

If the source and target CPUs are incompatible for VMotion, you can:

  • Perform a cold migration (rather than a VMotion migration), thereby removing VMotion CPU requirements as an issue.
  • Remove VMotion compatibility constraints by modifying the default bit-mask used by VirtualCenter or vCenter Server. Note that some modifications discussed in this knowledge base article are neither supported nor recommended by VMware for production environments. In general, masking any CPU features intended for applications (such as SSE3) is not supported for VMotion. Use of EVC is recommended for migrating virtual machines across CPU generations.

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VMware: Enhanced VMotion Compatibility (EVC) processor support (1003212)

May 20th, 2009 1 comment

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.


To use the EVC feature, you must be running ESX Server 3.5 Update 2 or higher with Virtual Center 2.5 Update 2 or higher and have only compatible processors that are listed in one of the following tables. EVC does not allow for migration with VMotion between Intel and AMD processors. Note the following restrictions:

  • The tables below are based upon public information. VMware has not verified all of these processors. For more information on which servers and processors are supported, see the Systems Compatibility Guide for ESX Server 3.5 and ESX Server 3i.
  • This list only covers server class processors compatible with the EVC baseline(s) and might not be a complete list.
  • You must ensure the BIOS settings for these processors enable Hardware Virtualization (if available) and Execute Protection. Default BIOS settings may not always enable these features. Hardware Virtualization is Intel VT on Intel processors and AMD-V on (supported) AMD processors. Execute Protection is Intel eXecute Disable (XD) on Intel processors and AMD No eXecute (NX) on AMD processors.

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