Removing a Processor from ESX Server

[warkaj]

So we got an idea in our department to remove a couple of processors from our ESX servers (they are only sitting around 8% utilization with 7-10 VMs on each of them).

I was wondering if anyone has powered down a licensed ESX server and done this before. Any pointers, advice?

I basically see it like this, they are licensed per processor so if we take away one processor and boot it back up it'll see it has 1 processor and then we can use the license to bring up another 1 processor ESX host. The processors are 3.33 MHz quad cores so I think it can handle just about anything we through at it (keeping exchange and sql machines on dual proc ESX hosts with lots of RAM though).

So there you have it, anyone got any ideas? I just wanted to post it out there and see what the concensus was in the community. Thanks!

[ScottBentley]

Hi

Never done it that way around but I dont see why it wont work, we have done it the other way and added a processor after installing ESXi and it picked up the second processor no problem, supplier didnt have one in stock for shipping with the server.

The licencing detected the change in number of processors ok.

Regards,

Scott

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[warkaj]

Thats what I was thinking Scott, just wanted to hear someone else having the same idea before I went and dove into this on a production server haha.

[DSTAVERT]

Your server may have an option in the BIOS to disable a processor. Yes you can reuse a processor but if you ever need to bring a server back to dual making sure you have the right stepping values can be difficult.

[edwardob · Accepted solution]

Your issue around removing a processor could be memory.

New processors with multi core have to be seated with memory boards that talk directly to the cpu because of the multiple cores and speeds.

So removing a processor could cause your box not to boot without removing the memory associated with those cpu's.

But from licensing and esx stand point, if the box boots it should work. Definitly something I have never done.

[AntonVZhbankov]

Yes, you can remove CPU.

But be sure that your CPUs are not NUMA (Nehalems, Opterons), because in this case you also lose half of your memory.

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MCSA, MCTS Hyper-V, VCP 3/4, VMware vExpert

http://blog.vadmin.ru

[warkaj]

To update this, I did in fact remove the CPU from the host after we shut it down. Nothing broke on start up, the license server saw we removed it and released a license. So yes... you can remove it and it'll be fine.