VMotion EVC?

[AWo]

What exactly does EVC (Enhanced VMotion Compatibility) care about? Is this some kind of validating the validation?

I assumed that the VMotion process already checks if moving a machine is possible including processor type and architecture.

[sbeaver · Accepted solution]

EVC can be enabled by selecting the VT and no execute bit options from the BIOS. What you get from using EVC is a widder range of hosts that you can add to the cluster and will allow vmotion to work. Say you have some older ESX server and want to add newer servers to the cluster. If the CPU stepping was to far apart vmotion would not work. With EVC setup it has the ability to make it work.

Steve Beaver

VMware Communities User Moderator

Orlando Area VMware User Group Leader

====

Co-Author of "VMware ESX Essentials in the Virtual Data Center"

(ISBN:1420070274) from Auerbach

*Virtualization is a journey, not a project.*

[malaysiavm]

As the promise of the major chipmakers today, to ensure the quad core, dual core, 6 cores and 8 cores processor to be compatible for any Vmotion capability, the EVC will help you to ensure the ESX host you deploy in the future with more cores tehnology will compatible to support the vmotion across the esx host which run in different cores processor. Without EVC, you may experience the incompatible issue within different range of quad core processors from Intel or AMD both.

Malaysia VMware Communities -

[azn2kew]

Steve,

So is this feature close to the advance configuration of a VM->CPUID Mask->Hide the Nx flag from guest->this will allow the VM to vmotion across? Or its something different but EVC seems a great feature to enable though.

If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!

Regards,

Stefan Nguyen

iGeek Systems Inc.

VMware, Citrix, Microsoft Consultant

[sbeaver]

If I understand it correctly when the cluster is created and EVC is enabled it sets the NxFlag to match those processors and when a new processor is introduced it works of that NX flag to fit in. So EVC will set the cluster to the lowest level processor in the cluster to keep uniformity.

[Omar_Muntslag]

Hi, was your assumption correct ? Will EVC "tune down" faster ESX hosts in the cluster to match the speed op the slowest host in the cluster ?

I have got 2 ESX hosts with 2.0GHZ cpu's and 2 ESX hosts with 3.0 GHZ cpu's in one cluster with EVC.

Will the 2 ESX hosts with 3.0 GHZ only run at 2.0 GHz ?

Regards,

Omar

[dpkenn]

Could another use for EVC setting be to move VMs to another Cluster if possible? Our setup is 8 - 8 node clusters using HP 460c blades striped vertically across four enclosures. Total of 64 blades/ESX hosts in 4-C7000 enclosures, in one rack. Each 8 node cluster shares a set of 8 or more 800GB LUNs but these LUNs are NOT zoned to other clusters. However, to move between clusters, we could set aside a LUN or NFS volume zoned to multiple clusters to be able to Storage vMotion and then vMotion between clusters to balance work loads. Each cluster has different processor model since they were bought a different times. The processor models range from Intel Xeon 5150 dual core to E5345 quad core to X5450 and E7340 quads.

Question is will it be beneficial to enable EVC on all clusters if we want to move VMs between clusters that have different processor models? OR will it not make a difference and could potentially cause performance issues or application problems? Consider everything else is setup correctly, ie. Storage zoning, Port groups, VLANs, etc... that will allow us to move between clusters.

Thanks,

D

[dpkenn]

Could another use for EVC setting be to move VMs to another Cluster if

possible? Our setup is 8 - 8 node clusters using HP 460c blades striped

vertically across four enclosures. Total of 64 blades/ESX hosts in

4-C7000 enclosures, in one rack. Each 8 node cluster shares a set of 8

or more 800GB LUNs but these LUNs are NOT zoned to other clusters.

However, to move between clusters, we could set aside a LUN or NFS

volume zoned to multiple clusters to be able to Storage vMotion and

then vMotion between clusters to balance work loads. Each cluster has

different processor model since they were bought a different times. The

processor models range from Intel Xeon 5150 dual core to E5345 quad

core to X5450 and E7340 quads.

Question is will it be beneficial to enable EVC on all clusters if we

want to move VMs between clusters that have different processor models?

OR will it not make a difference and could potentially cause

performance issues or application problems? Consider everything else is

setup correctly, ie. Storage zoning, Port groups, VLANs, etc... that

will allow us to move between clusters.

Thanks,

D

[Omar_Muntslag]

CPU's in hte EVC cluster will not be "slowed down" to match the slower cpu's.

A good article from VMGuy that explains it all : http://vmguy.com/wordpress/index.php/archives/38

[admin]

You might want to look at 'Enhanced VMotion Compatibility' section in the following white paper.

Bhavesh