Microsoft licensing and Proxmox cluster CPU core counts

[mgaudette112]

Hi,

I know somebody is bound to say "ask Microsoft", but Microsoft and their vendors are 1) usually unhelpful and 2) incentivized to make me buy licenses that I don't have to.

I am hoping someone with with both Proxmox knowledge and Microsoft insight can answer me.

Here is my situation (that I touched on briefly on another thread). I have 3 Microsoft Server Standard licenses. Each permit me to have 2 server instances (so a total of 6) and each allow those to be run on 16 CPU cores (16 core Hypervisor if virtualized, adding up as licenses are added). So those same 3 licenses also allow me to use 48 cores on physical machines/hypervisors.

I have scaled my Proxmox cluster precisely to this size (48 cores - 2 hosts with 24 cores each) on purpose (not entirely relevant, but while I do not use HA for now, but each server is sized to be able to run all VMs by itself. When I do updates I move all VMs manually to one host, update the other, reboot, and repeat on the other before I finally put the VMs back where they belong).

Here is the thing: I want to add more hosts, at least a third one to get to three for Ceph storage - it will NOT run any VMs, or if it eventually does only my non-Windows ones (Linux, etc.).

Does somebody know, from a Microsoft licensing perspective, do I need to cover the cores of those additional machines that would now be part of the cluster, knowing that they will never run a Microsoft OS as HA is not turned on and I would manually only move Windows VMs between node 1 and 2 that are already covered?

Any real insight is appreciated. Let's not turn this into an anti-Microsoft thread, regardless of our personal feelings.

 

[BobhWasatch]

Regardless of your feelings about Microsoft, they are the authority on their own licenses, not us random people on the Internet.

ETA: It is Microsoft that might sue you, so you should get the answer from them or from a reseller in writing.

 

[janus57]

Hi,

Technically speaking the license are per host, so your license should cover 2 hosts with 24 cores (and no you cannot split like you did, you should have 4 licenses).
And technically speaking you can only licence your node which are used to host windows VMs.

Source : profesionnal experience (msp/integrator) + http://download.microsoft.com/downl...958B/WindowsServer2016VirtualTech_VLBrief.pdf + https://www.microsoft.com/licensing...d/Licensing_guide_PLT_Windows_Server_2025.pdf

Please note this is subject to interpretation, I advise you to have everything confirmed by a reseller

Best regards,

 

[mgaudette112]

Hi,

Technically speaking the license are per host, so your license should cover 2 hosts with 24 cores (and no you cannot split like you did, you should have 4 licenses).
And technically speaking you can only licence your node which are used to host windows VMs.

Source : profesionnal experience (msp/integrator) + http://download.microsoft.com/downl...958B/WindowsServer2016VirtualTech_VLBrief.pdf + https://www.microsoft.com/licensing...d/Licensing_guide_PLT_Windows_Server_2025.pdf

Please note this is subject to interpretation, I advise you to have everything confirmed by a reseller

Best regards,

We did get all this figured out by a reseller (and I do have this in writing). But I think resellers are sometimes confused by the complexity of anything outside of very typical deployments.

I see what you mean by having 4 licenses split incorrectly (despite the reseller having approved the licensing). If anything I might just downgrade the hosts CPUs, they have more cores than I need.

I understand this is just your interpretation, it is helping my reread the licensing differently so I appreciate.

 

[mgaudette112]

Regardless of your feelings about Microsoft, they are the authority on their own licenses, not us random people on the Internet.

ETA: It is Microsoft that might sue you, so you should get the answer from them or from a reseller in writing.

I understand, I wasn't looking for a definitive, legally binding response, but trying to learn from people with more experience before I move to more formal enquiries.

I helps to know what you don't know, if you understand what I mean.

 

[janus57]

Hi,

despite the reseller having approved the licensing

Well, he shouldn't have, if you have 3 license for 16 core, you can assign license only to one host you cannot split the 16 cores between 2 different host (I think it's explicated in Microsoft docs).

For your use case I would use one 16 core + one 8core, so like that you have your 24 cores licensed, and can run 2 Windows VMs per node, and you have one 16 core in spare for a third node.

Best regards,

 

[mgaudette112]

Hi,


Well, he shouldn't have, if you have 3 license for 16 core, you can assign license only to one host you cannot split the 16 cores between 2 different host (I think it's explicated in Microsoft docs).

For your use case I would use one 16 core + one 8core, so like that you have your 24 cores licensed, and can run 2 Windows VMs per node, and you have one 16 core in spare for a third node.

Best regards,

I understand you say the reseller and I got the splitting part wrong.

But I don't understand your solution - I have the right to use 16 cores x 3, so I could have 32 cores on one servers and 16 on the other. Or, what I am now aiming for, 16 on three different nodes. Not sure how you got to 24 cores being a key number in this. Mind explaining further your thinking?

 

[janus57]

Hi,

Not sure how you got to 24 cores being a key number in this. Mind explaining further your thinking?

well, you said this :

2 hosts with 24 cores each

So that is why, with your existing license, the best is to do 16+8 (x2) that leave you 16 for a third node, or you can do 3 nodes with 16 cores; it all depends on your budget, the number of windows VMs and the load that you’re expecting on your nodes.

I have the right to use 16 cores x 3, so I could have 32 cores on one servers and 16 on the other

yes

Best regards,