Processors are grouped into families. Processors within a given family generally have similar feature sets.

Processor families are defined by the processor vendors. You can distinguish different processor versions within the same family by comparing the processors’ model, stepping level, and extended features. In some cases, processor vendors have introduced significant architectural changes within the same processor family, such as the SSSE3 and SSE4.1 instructions, and NX/XD CPU security features.

By default, vCenter Server identifies mismatches on features accessible to applications as incompatible to guarantee the stability of virtual machines after migrations with vMotion.

Server hardware’s CPU specifications will usually indicate whether or not the CPUs contain the features that affect vMotion compatibility. If the specifications of a server or its CPU features are unknown, VMware’s bootable CPU identification utility (available for download from the VMware website) can be used to boot a server and determine whether its CPUs contain features such as SSE3, SSSE3, and NX/XD.

For more information on identifying Intel processors and their features, see Application Note 485: Intel® Processor Identification and the CPUID Instruction, available from Intel. For more information on identifying AMD processors and their features, see CPUID Specification, available from AMD.