vMotion Error

We just added a 4th host into our cluster -- DELL R420. The other 3 older hosts are DELL 2950.

(3) DELL 2950 - 2 CPUs - Xeon E5420
(1) DELL R420 - 2 CPUs - Xeon E5-2450 ( is the new host)

When trying to vMotion to this new host we are getting the error message below. vMotioning to older hosts is not a problem.

vMotion Error Message
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
This is TO BE EXPECTED, when you have old and new processors in Host ESXi Servers.

VMware therefore designed EVC - Enhanced vMotion Compatibility. When this is enabled in your Cluster, you will be able to vMotion (Live Migrate VMs) between different hosts with different types of processors.

see these articles for further info:-

VMware KB: Enhanced vMotion Compatibility (EVC) processor support

VMware KB: EVC and CPU Compatibility FAQ

Have you created a Cluster ?

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Subhashish LahaCommented:
Have you enabled Enhanced vMotion compatibility (EVC) on Cluster?
pzozulkaAuthor Commented:
It is not currently enabled. Can it be enabled during business hours?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
EVC Modes compatible for your servers are

DELL 2950

EVC Modes:      Intel® Merom Generation,Intel® Penryn Generation


EVC Modes:      Intel® Merom Generation,Intel® Penryn Generation,Intel® Nehalem Generation,Intel® Westmere Generation,Intel® Sandy-Bridge Generation

So, to vMotion from Dell 2950 to Dell R420, you need to

1. Add all the Hosts to a Cluster.

2. Enable EVC Modes of either

Intel® Merom Generation


Intel® Penryn Generation

which is COMMON to both processors.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
It can be enabled in BUSINESS hours, but please note, you CANNOT Add a Power-UP VM to use a different CPU Mode, if the VM is on. Because it's actively using the processor.

So all your VMs on the new servers, will be using instruction sets higher than the EVC Mode, this will not affect the running of the VM, but it does mean, that VMs will need to be OFF, when added to the cluster, with the EVC Mode.
pzozulkaAuthor Commented:
We currently do not have any VMs on the new host. If we turn EVC ON and set it to Merom Generation and migrate all the VMs to the new hosts, what will happen when we retire the old hosts? We will want to turn EVC off at that point.

Does that mean we will need to power off all VMs and then power them ON in order to:

1) Allow vMotion (without EVC turned on)
2) To take advantage of new generation CPU features

pzozulkaAuthor Commented:
In other words, just confirming, after retiring old hosts, we can safely turn off EVC. After doing that, we will still need to power cycle the VMs in order to allow standard vMotion and take advantage of new CPU features? (Key point is power cycling the VMs)
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
EVC is just used, so you can vMotion VMs which are ON between different processor types (Intel or AMD, not mixed processors!)

When you retire your old hosts, nothing will happen. You turn off the hold hosts, the VMs will be on the new hosts, running ok, with a EVC Mode of Merom Generation. These VMs will run just as well with EVC Mode on or off.

If you want to disable EVC Mode (turn if off), you will not really notice VMs taking advantage of new instruction sets, but if you want to fiddle, and turn it off, same applies, turn off all VMs, and remove, and then power ON.

Are you programming, and need to take advantage of the CPU instructions?

Most organisations leave EVC on.
pzozulkaAuthor Commented:
Not programming, but thinking that there must be new CPU instructions that can be taken advantage of. Afterall, it has been about 6 generations of CPUs between the old hosts and the new hosts. So I'm assuming there is better technology available in the new CPUs that VMware can utilize.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
It's not VMware using the CPU instructions, but the VM OS!

switching to current CPU set would allow the VM OS to use

All features of Intel Core2 CPUs and additional CPU features including SSE 4.1, SSE4.2 and POPCOUNT, AES and PCLMULQDQ,  AVX, XSAVE and ULE, ENFSTRING, F16C, FSGSBASE, SMEP and CPUID Faulting!

So if you want to turn it off, VMs would have access to above! But I do not think you would miss them!

anyway up to your organisation, if you disable afterwards.
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