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vMotion/EVC incompatibility issues due to AES/PCLMULQDQ (1034926)

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Export restrictions for some models (Clarkdale, Westmere-EP, Westmere-EX, Sandy Bridge, Ivy Bridge) of Intel CPUs require that the Advanced Encryption Standard (AES) and Carry-less Multiplication (PCLMULQDQ) features be disabled. Some OEM BIOS software might also have AES/PCLMULQDQ disabled by default.  

vMotion operations between hosts that have the same model/class CPUs will fail if AES/PCLMULQDQ features are enabled on one of the hosts involved in the operation and disabled on the other.

The error message contains the following information:

Host CPU is incompatible with the virtual machine's requirements at CPUID level 0x1 register 'ecx'.
Host bits: 0000:0010:1001:1000:0010:0010:0000:0011
 Required: x000:0x0x:10x1:1xx0:xxx0:xx1x:xxxx:xx01
Mismatch detected for these features:

Problematic BIOS software includes, but might not be limited to, Dell BIOS versions 2.1.9 and 2.1.15 and Cisco UCSM prior to version 1.4(3q).

For EVC, when you attempt to add the same models to clusters configured with the highest possible EVC mode based on the micro-architecture, the following error message appears:

The host's CPU hardware should support the cluster's current Enhanced vMotion Compatibility mode, but some of the necessary CPU features are missing from the host. Check the host's BIOS configuration to ensure that no necessary features are disabled (such as XD, VT, AES, or PCLMULQDQ for Intel, or NX for AMD). For more information, see KB article 1003212.

For example, some Westmere micro-architecture processors that have AES/PCLMULQDQ features disabled are not permitted into Intel Westmere (Xeon 32nm Core i7) EVC clusters. If these features cannot be enabled in the BIOS, the host will only be admitted to the Intel Nehalem Generation mode or below.


  1. Check your BIOS settings for an option to enable the features (look for "AES" or "Advanced Encryption Standard").   Note: In some cases, you may need to enable the Monitor/Mwait feature.
  2. Ask your system vendor for a new BIOS to enable the features.
  3. If you are unable to enable the features, use a Nehalem or earlier EVC cluster for these CPUs if you need to vMotion between them.

Additional Information

For translated versions of this article, see:

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  • 17 Ratings