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I have a production cluster of 16 Xeon 56xx-series hosts running ESXi 4.1 with a vCenter 4.1 managing them for HA and DRS. They're setup as using the EVC mode "Intel Xeon 32nm Core i7", but I want to add some older 55xx-series hosts which obviously can't run in that mode (they'll need the "Intel Xeon Core i7" mode instead).

You can increase but not decrease EVC mode 'live' and I can't really take down all the guests, not easily anyway. Is there a way of doing this without?

Thanks in advance.

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I'm trying to do the same thing. Unfortunately, there still doesn't seem to be a good solution short of powering off every VM. – ewwhite Jul 19 '11 at 1:40
No, and unless I've missed something this isn't addressed at all in v5 – Chopper3 Jul 19 '11 at 6:52
up vote 6 down vote accepted

I don't believe there is a way to do it live. The point of EVC is that it ensures all the hosts in the cluster have the same processor capabilities available to the VMs so the VMs are powered on with those processor options available to them. If you were to downgrade the EVC mode you would be eliminating processor functionality that those VMs are (potentially) using which would cause problems.

Check this out,289483,sid179_gci1513907,00.html

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Well I knew this obviously but was rather hoping someone had worked out a way of doing it that I wasn't aware of, guess not. I'll just have to accept it and schedule some downtime. – Chopper3 Nov 6 '10 at 10:42

We had to do this with 4.0, and no, there is no way to do it live.

The easiest way to achieve this is to make a new cluster with the lower EVC, move stuff off hosts, and migrate the hosts one by one to the new cluster. Then, with each host being transferred to the lower cluster, cycle the guests to move them.

Downtime can not be avoided, alas.

I will leave it up to you whether "easiest" was sarcastic or not ;)

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You can actually do this live. Make a new cluster with the lower EVC hosts, ensure connectivity to the same shared storage platform, and vMotion guests over one by one.

As you saturate the capacity of the lower EVC hosts, put the higher hosts into maint mode and move into the lower cluster. Once re-enabled, these will be participating in the cluster at a lower EVC mode and all will be well.

Do this until the entire workload is transferred from A to B and remove the higher cluster from vCenter when you are done.

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But this doesn't work (not with v4 anyway, not tried it with v5), as the vmotion fails because of EVC mode mismatch. – Chopper3 Jan 28 '12 at 22:55
Indeed, this will not work. It's impossible to do this with VM's powered on, as the EVC mode tells the hypervisor what kind of CPU features the virtual cpu's should bring. – pauska Jan 29 '12 at 0:54

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