how to know how many vCPU i can use for creating VMs?

[bappo]

Hi,

I am reading some article that says, to calculate vCPU is using this formula:
(Threads x Cores) x Socket = vCPU

I am curious, is that formula is right?

Let's say i have a physical server with 1 CPU @ 4 Cores/8 Threads and 32GB RAM with Proxmox VE running inside
and with that formula, that means i have 32vCPU that i can use.
then, i create 32 VMs using old windows 7 with each VM have only 1vCPU, and 1GB RAM.

is that possible ? or how many VMs i can create with each VM have only 1vCPU with that server?

Anyway, english is not my native language, so im sorry if there are any mistakes words

 

[LnxBil]

(Threads x Cores) x Socket = vCPU

Threads + Cores and it is the maximum (useful) upper bound per ONE VM.

 

[LnxBil]

how about 1vcpu per one VM, but there is 32VMs? is that possible with 4 cores/8 threads CPU ?

That depends what the VMs do, but in general is this the norm to overprovision the CPUs. They are sedomly used all the time in all VMs.

 

[B.Otto]

Yeah generally you would overprosion the vCPUs since they are never all on full load. What you should not do is to give one VM more vCPUs than the server has availiable threads.

So in your case (8 Threads) it is okay to create 8 VMs with 2 vCPUs, but you should not give one VM 16 vCPUs.

Overprovisioning RAM is a bit more dangerous, I would not recommend it. Also these days I would not give a Windows VM less than 2 vCPUs - but it all depends on what the load inside the VM will look like.

 

[LnxBil]

Also these days I would not give a Windows VM less than 2 vCPUs

yes, and 2 GB RAM is also a low level which also swapps, 32 GB disk is also not enough ... what a useless beast ... just for the OS without any programs.