Dell EMC VxBlock 240 Administration Manual page 68

When upgrading Cisco UCS rack servers in a Converged System, consider the following guidelines:
•
Enable EVC mode only if you are adding or planning to add hosts with newer CPUs to an existing
cluster.
•
Cisco UCS rack servers all support EVC mode Intel
Individual Cisco UCS rack servers support several EVC modes, but only Xeon Core i7 is a
commonly supported mode across all Cisco UCS rack servers. If the CPU feature sets are
greater than the EVC mode you are enabling, you may need to power down all VMs in the cluster
and enable or modify the EVC mode.
•
Some Cisco UCS rack servers support additional CPU features (such as those provided in 32-
nanometer EVC mode), but some of those features might not be enabled in the BIOS (due to
U.S. export rules). To ensure complete and reliable vMotion compatibility when mixing rack types
in a single cluster, use Intel Xeon
•
If all the Cisco UCS rack servers in the cluster have the same CPU type, set the EVC mode to
that of the CPU architecture. This allows vMotion compatibility between Cisco UCS rack servers
and other hosts.
•
Set the EVC mode before you add Cisco UCS rack servers with newer CPUs to the cluster. This
eliminates the need to power down the VMs running on the rack servers. Setting a lower EVC
mode than the CPU can support may hide some CPU features, which may impact performance.
Proper planning is needed if performance or future compatibility within the cluster is desired.
Related information
Enable EVC on an existing cluster
vMotion/EVC incompatibility issues due to AES/PCLMULQDQ
®
Nehalem Generation (Xeon
® ™
Core i7 EVC mode.
® ™
Core i7).
Managing storage resources | 68