topic Re: Physical CPU to vCPU in ESXi Discussions

Physical CPU to vCPU

BoLaw — Thu, 19 Oct 2023 03:14:34 GMT

Hi Bro

I would like to inquire about the calculation method for determining the of vCPUs. As below, am I correct?

ESXi 6.7
Xeon GOLD 5220 2.2G x 2Sockets 18Cores 36Threads (2x18x36= 1296vCPU)

Xeon GOLD 5222 3.8G x 2Sockets 4Cores 8Threads (2x4x8= 64vCPU)

E52680V3 x 2Sockets 12Cores 24Threads (2x12x24= 576vCPU)

Xeon GOLD 6130 x 2Sockets 16Cores 32Threads (2x16x32= 1024vCPU)

Xeon Platinum 8260 x 2Sockets 24Cores 48Threads (2x24x48= 2304vCPU)

ESXi 8.0
Xeon Gold 6430 2.10 x 2Sockets 32Cores 64Threads (2x32x64= 4096vCPU)

Xeon Gold 5415+ 2.90 x 2Sockets 8Cores 16Threads (2x8x16= 256vCPU)

As I am planning purchase and install ESXi 8 using Xeon Gold 6430 and Xeon Gold 5415+ for replace the ESXi 6.7
it will occupy physical CPU, so I need reduce the number then calculate the vCPU?

Such as keep one cores for the ESXi (Xeon Gold 6430 2.10 x 2Sockets 31Cores 64Threads (2x31x64= 3968vCPU))

Please help to guidance if incorrect..

I have a query regarding this matter. Your assistance in clarifying this would be greatly appreciated. Thank you.

Re: Physical CPU to vCPU

BoLaw — Thu, 19 Oct 2023 03:51:01 GMT

I am very confused. As I research on web calculation on vCPU and logical cores method also is same.

https://forum.huawei.com/enterprise/en/what-is-machine-learning-explained-in-detail-part-1/thread/667281940820148224-667213860102352896

Number of vCPUs = (No of Threads x No of Cores) x Physical CPU Number

https://baiweiblog.wordpress.com/2017/10/27/how-many-physical-and-logical-cpu-cores-in-your-computer/

These threads are the core’s logical capabilities. The total number of logical cores = CPU sockets × physical cores per socket × threads per physical core.

https://www.virten.net/vmware/vmware-vsphere-esx-and-vcenter-configuration-maximums/

But on below link showing ESXi 8.0 Host Maximums

Logical CPUs per host =896

Virtual CPUs per host = 4096

Re: Physical CPU to vCPU

scott28tt — Thu, 19 Oct 2023 06:08:47 GMT

What in practical terms (eg. running VMs to an acceptable level of performance) are you trying to work out exactly?

Re: Physical CPU to vCPU

BoLaw — Thu, 19 Oct 2023 08:46:56 GMT

Thanks Scott28tt,

As I need replace the old ESXi 6.7 server to ESXi 8.x server for mirgrate the VM(s), so I need calculate method.

Re: Physical CPU to vCPU

scott28tt — Thu, 19 Oct 2023 09:13:11 GMT

But you don't give any indication as to the current level of performance, whether your VM population will grow, do you have to consider HA, vMotion, DRS...

Re: Physical CPU to vCPU

BoLaw — Thu, 19 Oct 2023 09:34:11 GMT

Thank you for your reminder Scott28tt,
Yes I will buy more than one ESXi 8.x server for the HA and failover.
Will using vMotion/Cold vMotion for mirgate the VM(s).

Background
Over 10 ESXi 6.7 Server need to migrate to new purchase (assume 7-9) servers and install ESXi 8.0
On old ESXi 6.7 over 200 VM(S), total using over 900 CPU and over 3000GB RAM

Query
For the VM population grow, I need clarify the calculation method then estimate the Qty for migration (I will take some buffer for overload)

Re: Physical CPU to vCPU

battybishop — Thu, 19 Oct 2023 10:04:41 GMT

You do not multiply all of these together e.g.

Xeon GOLD 5220 2.2G x 2Sockets 18Cores 36Threads = 2(processors) x 36(threads) = 72 Logical Processors (vCPU)

purchasing is based an units of 32 cores per processor so your proposed ESXi 8 processors would both need 2 licences

Xeon Gold 6430 2.10 x 2Sockets 32Cores 64Threads = 2 VMware licences

Xeon Gold 5415+ 2.90 x 2Sockets 8Cores 16Threads = 2 VMware Licences

Re: Physical CPU to vCPU

BoLaw — Thu, 19 Oct 2023 10:18:18 GMT

Thanks for share the Licenses information. Battybishop.

As I need migrate over 10 ESXi 6.7 host migrate to ESXi 8.x host

On new ESXi 8.x host is propose using Xeon Gold 6430 2.10 x 2Sockets 32Cores 64Threads (2x64= 128vCPU)

If I have VM(s) which total is 900 CPU in over 10 ESXi 6.7 host, so I need 900/128 for the = 7.03 host, it mean I need purchase 8 Qty ESXi 8.x host for migration. Am I right?

Re: Physical CPU to vCPU

battybishop — Thu, 19 Oct 2023 10:33:01 GMT

Please bear in mind that the second thread is a achieved by Hyperthreading so is not equivalent to a true core.

Without knowing other information like memory network capacity, processor usage etc. and basing it on purely vCPU then 8 would be minimum but would give little room for moving machines around for patching ESXi, covering off high CPU workloads or providing resilience for potential hardware failures, I would recommend a minimum n+1 so 9 hosts with 2 processors (32cores) = 18 VMware processor licences, if I remember correctly you buy these in 2 processor bundles but always check with your VMware reseller.

Re: Physical CPU to vCPU

BoLaw — Fri, 20 Oct 2023 01:09:08 GMT

battybishop! thanks for your guidance and opinion.