Filed Under (Geekspeak) by Justin on 2008-04-21

Are you planning to deploy VMWare Server, VMWare ESX, Mictosoft Virtual Server, HyperV or some other virtualization technology and have no idea where to start trying to figure out what licenses you need? Let me see if I can clear this up for you a little…

The topic of Microsoft licensing in a virtual server/machine environment is a topic of frequent discussion in the CITRT IRC channel, so I feel like I’ve become a bit of an expert by observance. The question came up again today on itDiscuss, so I decided to write it all down in one place and then chase down some links so we could have this documented once and for all.

Here are the basics:

  1. Windows Server Standard – One instance. Period. Do not pass Go. Do not collect $200.
  2. Windows Server Enterprise – One physical install + four additional virtuals
  3. Windows Server Datacenter – One physical install + unlimited virtuals**

To back up number two above, here’s a quote from an FAQ found on Microsoft.com:

Licensing does not depend on which virtualization technology is used. With a license for Windows Server 2003 R2, Enterprise Edition, you can run one instance of the software in a physical operating system environment and up to four instances in virtual operating system environments. With VMWare GSX Server, this means you can run one physical instance plus four virtual instances. With VMWare ESX Server, it means you can run four virtual instances because there is no need for a physical instance.

As you may have noticed from that quote, Microsoft is surprisingly platform agnostic in regards to which virtualization technology you choose (MS Virtual Server, VMWare, Xen, etc). For more information, checkout the whitepaper pubished last year titled Licensing Microsoft Server Products with Virtual Machine Technologies. Their indifference may have something to do with the many accusations and lawsuits they continue to face in regards to their monopolistic power. Regardless of the reasoning, it’s good news for everyone.

One rather important thing to keep in mind when thinking about licensing Microsoft Server products is that they are licensed per CPU socket, not CPU core. Can you say “THANK GOODNESS!”? This applies equally to VMWare ESX – you need enough HOST licenses of Windows Server to cover each physical processor socket in your ESX cluster.

It’s also important to keep in mind the fundamental differences in the various versions of Windows Server. For example, Server Standard (32-bit) is limited to accessing 4GB of RAM. This would likely be a non-issue for a guest install, but you certainly wouldn’t want to limit your Host box to that little memory. It’s not totally scary, just do your homework and you’ll be fine.

Microsoft has provided us with this handy little Licensing Calculator which should help you make sense of which version will be right for you and your implementation.

One final note (as denoted with ** above): Make sure you’re aware that with Datacenter Edition, you also need per-user or per-device CALs.

If anyone sees an inaccuracy in the information I’ve provided, please do leave a comment and I’ll update this post accordingly. Thanks to all the guys in IRC for helping compile and track down info, specifically, Tony Dye, Chris Green, and David Szpunar.

(4) Comments   


Bobby Stewart on 21 April, 2008 at 6:29 pm #

VMware’s discussion of Microsoft’s licensing (think “Communist Manifesto”).


OK, they make some good points but I don’t think Microsoft is in business to GIVE stuff away.

Jim Michael on 21 April, 2008 at 6:39 pm #

I would add that the extreme price break charity licensees get for Windows Server Datacenter makes it a much-more-attractive option than would normally be the case. With non-charity licensing there is a large price difference between Enterprise and Datacenter editions, but with charity licensing Datacenter is just about the *same* price (or even cheaper, in some cases) than Enterprise.

This makes it a no-brainer for a non-profit that wants to run more than four Windows VMs on a single server. Even taking into account Datacenter is “per socket” it is still a bargain at charity pricing.

Derek Mangrum on 22 April, 2008 at 12:48 am #

I too have been doing a lot of research on this topic and can confirm what you have posted here. But, my next question always is (and I have yet to find a definitive answer for this): Assuming I have DCE on my VM Host box (allowing unlimited VMs), what license key do I use for my OS install on my various VMs?

For example, my VM Hose is running Server 2008 DCE. Then, I want to host 7 Windows 2003 server Enterprise Edition. What license key do I use on the 7 VMS?

This part is very confusing to me.

Justin on 22 April, 2008 at 7:52 am #


I’m pretty certain that you just use the product media and key for Datacenter Edition. To be totally honest, it’s mostly irrelevant. The key is just that – a key – not the actual license. As long as you own enough licenses, legally, you’re covered. For example, throughout my company, I have a mess of 30-40 different licenses and copies of Windows XP Professional. However, I’m definitely guilty of not using the specific product key that’s attached to the side of the machine’s case when doing reinstalls.

Keep in mind, I am not a lawyer or a MS licensing expert – these are purely my thoughts, experiences, and opinions.

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