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vmware EVC

A reseller has advised me that i really need to buy new servers to utilise EVC for HA etc.

Am i really going to notice and performance issues should i stick with older non evc compatible CPU's?
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CHI-LTD
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CHI-LTD
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1 Solution
 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
HA does not use EVC, EVC is used for vMotion.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
what are you trying to do?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
the issue when building Clusters with old and new servers, you use EVC mode to ensure compatible CPU instructions are used on VMs, when using vMotion between servers.

So, newer CPUs have newer instructions sets, so you select a common EVC Mode Baseline hat both your old server CPU and new CPU servers understand.

does not affect performance, but needed when you build clusters with old and new servers.
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CHI-LTDAuthor Commented:
sorry meant vmotion.
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CHI-LTDAuthor Commented:
we will use same spec but older boxes.  so no issues there then....
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
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PaulNSWCommented:
EVC is a setting in VMWare which allows vMotion between different generations of processors

You don't need EVC to get HA, but you need to enable EVC if you buy new servers with a different generation of processor
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
No issues, just remember to enable EVC Mode, schedule downtime, turn ALL VMs OFF, and then Enable EVC Mode in the Cluster for ALL Servers.

EVC Mode cannot be enabled when VMs are ON!
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CHI-LTDAuthor Commented:
The knock-on affect of having 2x different boxes:

1. One with evc cpu and the other without evc cpu - with evc enabled means?
2. As above - witout evc enabled means?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
You cannot add different CPU types without EVC Enabled.

EVC is enabled on the Cluster. It's not enabled for one server or the other.
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PaulNSWCommented:
EVC isn't a function of the CPU

It's a function of VMware

It will be either enabled for ALL hosts, allowing vMotion between different processor generations, or disabled for ALL hosts, meaning you can not vMotion between all hosts, only those with the same processor generation
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Enhanced vMotion Compatibility (EVC) simplifies vMotion compatibility issues across CPU generations. EVC automatically configures server CPUs with Intel FlexMigration or AMD-V Extended Migration technologies to be compatible with older servers.
 
After EVC is enabled for a cluster in the VirtualCenter inventory, all hosts in that cluster are configured to present identical CPU features and ensure CPU compatibility for vMotion. The features presented by each host are determined by selecting a predefined EVC baseline. VirtualCenter does not permit the addition of hosts that cannot be automatically configured to be compatible with the EVC baseline.
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CHI-LTDAuthor Commented:
OK, makes sense, i think.  

So a DL360 g5 with non EVC CPU and a DL380 G7 with EVC CPU in a cluster will not work at all for vmotion, correct?  Or will the newer server run slower with evc disabled when vmotion runs?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Correct.

It does not make any difference to the performance of the server.

You are just selecting the same CPU instruction set to be used across all VMs.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Yes, that's the link I posted in http:#a37757408
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