STI-RIP
Contributor
Contributor

ESX remove a CPU

Perhaps someone can help answer this question, I have been looking everywhere for an answer...

One of our admins wants to remove a physical CPU from an ESX server that has already been configured. The reason is because of MS Licensing so as to not have to worry about purchasing additional licenses to match the number of procs and cores the server has.

I'm not sure if this is a good idea and if there is a better way.

Is it possible to remove a physical CPU from an ESX server and are there any issues that arise from removing the CPU. I understand it would diminish the capacity of that server, but does the ESX Server continue to function?

Thanks for any assistance anyone can provide.

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5 Replies
Mortendb
Contributor
Contributor

Hi

All the CPU's today are multicore so you shouden't have an issue.

Just remember all the stuff with cooling, memory channels and so on.
Depinding on  your VMware licensing you also save a VMware license..

/Morten

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STI-RIP
Contributor
Contributor

OK, so a CPU can be removed.

This action would not cause any issues with ESX or the existing Virtual Machines. - That's good news.

But you are correct, we would need to re-org the memory since we would be losing a CPU.

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IRIX201110141
Champion
Champion

Even after thinking twice i would says the above isnt true as long we are not talking about a 4 socket box or so.

With REMOVING a CPU you will not save MS licenses. Yes you can save  vSphere LICS or other CPU based software costs.

With DECREASING pCores within the Server BIOS you can adjust MS licensing costs most likely and you will not loose pMemory.

The rule of thumb when it comes to MS Server licensing:

  1. a minimum of 8 Cores per Socket
  2. a minimum of 16 Cores per Host
  3. All configured Cores needs to be licensed

Regards,
Joerg

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STI-RIP
Contributor
Contributor

Yeah, and that's the reason why the admin wants to remove a CPU - this removes 40 cores. He has a total of 80.

He has two CPUs 40 cores each. MS Licensing is costly.

My end goal was to make sure that by him removing a CPU he wasn't going to cripple the environment.

If there are negative affects of removing the CPU, it would be good to know so as to avoid a catastrophe.

Thanks

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IRIX201110141
Champion
Champion

Understood... but maybe your ESXi admin isnt the best in math.

Instead of removing a complete CPU and loosing half of the DIMMs, PCIe Lanes/Slots please go into the BIOS and reduce the number of Cores to 20.  2x20 is 40 which is the same as 1x40 but not loosing half of the system.  We leave NUMA out of the game here.

There is also less risk that you damage the system when simple modify a BIOS setting compared with fiddling around with the pCPU.

Be sure your Admin talk about pCores and not HT when it comes to the 2x40. I havent seen a lot of Intel based CPUs with 40p Cores each compared to 20 and HT enabled.

About MS licensing.... the rules haven't change since the release of Windows Server 2016 which was 7 years ago.

Edit:
I have my doubt about the 40 pCore because this means your about the limit of the 32 Core of vSphere 7. I assume youre have 2x 20 and with activated HT and this end up to the 80 logical CPUs. But windows doesnt need licensed for logical CPUs... just for the physical ones.

 

Regards,
Joerg

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