[SOLVED] How PVE distributes CPU cores and RAM to VM's

[pixel24]

Hi@all,

I would like to install a small PVE setup at my brother's house. Single host, local LVM and 2-3 VM's.

We do not have very many resources. 6 cores and 16GB RAM. If I define the number of cores and RAM in the VM. Is this fixed or does PVE distribute them depending on the load?

Example:

VM-1: 6 cores / 12GB RAM
VM-2: 6 cores / 12GB RAM

This is in total more than is available. This should not work like this, right?

Is there a way to tell PVE:

"For all VM's in total 6 cores and 16RAM may be used. Distribute this according to load?"

with best
pixel24

 

[apoc]

Example:

VM-1: 6 cores / 12GB RAM
VM-2: 6 cores / 12GB RAM

Bad idea!
That will only give you a lot of trouble!
If the host has 6 CPUs the biggest VM should be 4 vCPUs.
And you might even see that the VMs are slower with 4 vCPUs vs. lower amount (2 vCPUs).

This is in total more than is available. This should not work like this, right?

It can work. Through swapping memory to disk and scheduling CPUs - that's what hypervisors do. But that overcommittment won't work nicely.
The VMs are permanently in concurrence to each other and alongside in concurrence to the host too.
Bad bad idea!

Leave at least 1 Core and 2 GB dedicated to the host. I'd recommende even 2 vCpUs and 4 GB memory.

 

[pixel24]

ok, i get it. thanks for the help.