VMotion is working between non-EVC and EVC Enabled Clusters (How)??

[ncarde]

This one has me stumped:

-Historically we have not been able to vmotion live from ESX 3.5 Update 4 Non-EVC Clusters to 3.5 U4 EVC Enabled Clusters (VMotion throws incompatability errors).

-We recently upgraded all of our Hosts to ESX 4 Update 1 and suddenly I am able to VMotion from Non-EVC Hosts (Intel 5335) to EVC Hosts (Intel 5650).

I was preparing to schedule outages to cold migrate as we have done in the past but if this works without an outage and is supported....

Seems too good to be true!

Did moving to ESX 4 Update 1 relax some sort of CPU masking behavior, etc.?

Should I still power cycle the VM's to be on the safe side...?

Thank you.

[AndreTheGiant]

It depends on the baseline that you have in the EVC cluster.

If the baseline "change" the new CPU to the same level of Intel 5335, then you can use vMotion also on this kind of host (without EVC on them because are already the right baseline).

Andre

[ncarde]

Thank you, Andre -- it does indeed look like the Target Cluster has enabled the lowest level of compatibility by default (Intel Xeon Core 2) which supports the Source Cluster's VM's (Intel 5335). In my previous scenario the Source must have been prior to Xeon Core 2)..

So basically the VM's are retaining their old masks and applicatins within VM's are unable to use any of the newer (in this case, Nehalem) chipset functionality - is that correct?

Are the VM's losing out on any enhanced performance capabilities by using this method vs. a cold Migration?

If the VM's are power cycled at a later date do their masks automatically change?

Thank you for the education!

[AndreTheGiant]

So basically the VM's are retaining their old masks and applicatins within VM's are unable to use any of the newer (in this case, Nehalem) chipset functionality - is that correct?

You loose some registry and SSE instruction... but not too much (or part typically not used).

You do not loose HT, new VT-.. functions, bigger cache and so on...

Are the VM's losing out on any enhanced performance capabilities by using this method vs. a cold Migration?

Usually no... maybe if you have some special multimedia or CAD applications...

If the VM's are power cycled at a later date do their masks automatically change?

In case of a cold migration to a non EVC cluster or host, the mask is removed.

Andre