Many VM so many cores?

Joseph Chrzempiec

Well-Known Member
Jun 9, 2016
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Hello, I watched a guy on youtube that runs a proxmox server. His server is a 8 core 16 thead server with 64GB of memory. He has 6 VM each vm 4 cores and 4GB of memory. Now to me in my head that doesn't match up with what his hardware has. my question is how is it possible to run 6VM with 4 cores and 4Gb of memory all at the same time with only 8 core CPU? That would add up to 24 core system which he doesn't have. Is he sharing cores between each vm so if its not really being used that the rest of the resouces can help out other VMs? That is what I'm unsure about. I can't ask him because his command are blocked and no way of getting a hold of him.

Joseph
 
Is he sharing cores between each vm so if its not really being used that the rest of the resouces can help out other VMs?
That is how virtualization works and the main idea behind it. Not every VM needs the all the (cpu) power it has assigned all the time. Therefore those systems work by utilizing more combined of your hardware than each system would require if it'll run on its dedicated hardware.
 
That is how virtualization works and the main idea behind it. Not every VM needs the all the (cpu) power it has assigned all the time. Therefore those systems work by utilizing more combined of your hardware than each system would require if it'll run on its dedicated hardware.

I did not know that. I always thought once you Set how many cores and memory to a VM it's locked to that vm. I did not know you can share the same cores to another vm if it's not using all them cores.
 
Keep in mind that a VM isn't using real hardware unless you make use of PCI passthrough. It's using virtual CPUs, virtual RAM, virtual NICs, virtual disks, virtual GPUs and so on. Simplified: Your VM is just a program and you can run as many programs as your ressources can handle. Think of it like running 24 programs in parallel on a 8 core CPU. There you also don't wonder that it's possible to run more than 1 program on each CPU core at the same time.
 
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