Windows - cores - and licenses


Renowned Member
Sep 12, 2011
My head is swimming as I'm trying to figure out how to build this system. I'm hoping to build a system with two Windows Server 2019 VMs on it with heavy workloads, and one with SQL loaded as well. And a third Windows 10 Professional VM on the same machine. My single 3440 2.4Ghz processor has six cores.

I read on another thread that I leave 1 core for Proxmox and then tell each of my Windows machines to use the rest of the cores, which they will share but each think they have access to that many cores. So with a 6 core CPU I would tell EACH of the Windows machines to use 5 cores? Question #1) Is that correct?

I also read that I need to buy Windows licenses based on the total number of cores but a single license covers up to 16 cores. Question 2) Since I only have six cores does that mean I just enter my standard Windows license for each VM (total of two Windows Server and 1 Windows 10 license)?
Our documentation has a chapter about CPU sockets and cores, stating for example
It is perfectly safe if the overall number of cores of all your VMs is greater than the number of cores on the server
Especially the part about Resource Limits should be interesting for you.

The only place where you can get reliable information about Windows Licensing is from Microsoft itself.
Thank you. I did see the discussion regarding Microsoft's licensing debate. Ugg. I saw posts that gave a conflicting info on the cores. One in particular said I needed to leave 1 core for Proxmox and then could divide the remaining cores over various Windows VMs but I couldn't go over the total number of cores. That's not true of course (as I've since learned).

The Resource Limits is indeed interesting. Where does a person set the cpulimit?
Where does a person set the cpulimit?

For an existing VM you go to Hardware->Processors->Edit and tick the "Advanced" check box left of the OK and Reset buttons at the bottom of the pop up window. During VM creation you can tick the check box in the CPU tab.


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