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pinkerton
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Replacing CPUs in ESXi Hosts - changes to ESXi/VM configuration necessary?

Hi,

we are planning to replace the Intel Xeon E5520 4-Core CPUs in our HP ProLiant DL380G6 ESXi Servers with Xeon X5670 6-Core CPUs. Do we have to perform any changes to the ESXi/VM configuration due to the replacement? I know that the model type of physical CPUs is shown in the operating guest System. Is it necessary to reboot all VMs in order they can work with the new CPUs?

Thanks
Michael

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kermic
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In worst case you will need downtime comparable to "reboot only" (or shutdown, (move to new host), powerup, reboot).

It's a bit strange that support scares you with downtimes, AFAIK it should be easy doable with EVC. Of course it depends on zillion other factors but in general that is what EVC was designed for. Is that really VMware Support, or 3rd party?

On the other hand it's definitely much more safe to be prepared for some downtime, as if you will avoid it, you will not blame anyone Smiley Happy

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kermic
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Intel 55xx is Nehalem, 56xx is Westmare.

To avoid downtime you can enable Nehalem EVC mode on your cluster before adding any hosts with 56xx CPUs. If that can be done without issues, once you add a host with a newer CPU, the newer instructions will be masked out and you should be able to do live migrations in any direction (55xx to 56xx and back) without issues.

Here you'll find some more info on EVC processor support: http://kb.vmware.com/kb/1003212

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JCMorrissey
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Hi,

Nothing needs to be done at the VM level. If you are running in a cluster and have different CPU models (same architecture will be required) just make sure to enable EVC (enhanced vmotion capability) that way your VM's can freely move about (above models should be compatible with each other but worth checking the HCL).

Please consider marking as "helpful", if you find this post useful. Thanks!... http://johncmorrissey.wordpress.com/
pinkerton
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Thank you. I just talked to the VMware support about my question either and they said I need a downtime for all VMs, otherwise the VMs will not work with the new CPUs. So I guess that is not correct?

Or is the reboot only needed once I replaced all CPUs and change EVC from Nehalem to Westmare?

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kermic
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And speaking of how guest will react to CPU upgrade - no easy answer here, it depends heavily on guest OS. Normally there should not be any issues nor reconfiguration needed, however I have seen some older Windows guests throwing out the famous "I've finished installing your new hardware and now I'm ready to reboot" message when starting up for first time after cold migration to a host with different CPU.

kermic
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In worst case you will need downtime comparable to "reboot only" (or shutdown, (move to new host), powerup, reboot).

It's a bit strange that support scares you with downtimes, AFAIK it should be easy doable with EVC. Of course it depends on zillion other factors but in general that is what EVC was designed for. Is that really VMware Support, or 3rd party?

On the other hand it's definitely much more safe to be prepared for some downtime, as if you will avoid it, you will not blame anyone Smiley Happy

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pinkerton
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Thanks again for your reply. Actually it was directly VMware Support. But maybe they just wanted to advise the safe way Smiley Happy I'm going to test whether it works without downtime, but will prepare for downtime in case I need it. Thanks again for your help.

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