Microsoft Licensing and Server Virtualization

Are ye plannin' t' deploy VMWare Server, VMWare ESX, Mictosoft Virtual Server, HyperV or some other virtualization technology and have no idea where t' start tryin' t' figure out what licenses ye need? Let me see if I can clear this up fer ye a little…

The topic o' Microsoft licensin' in a virtual server/contraption environment is a topic o' frequent discussion in th' CITRT IRC channel, so I feel like I’ve become a bit o' an expert by observance, by Davy Jones' locker. The question came up again today on itDiscuss, so I decided t' write it all down in one place and then chase down some links so we could have this documented once and fer all.

Here are th' basics:

  1. Windows Server Standard – One instance, with a chest full of booty. 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

Licensin' does not depend on which virtualization technology is used. With a license fer Windows Server 2003 R2, Enterprise Edition, ye can run one instance o' th' software in a physical operatin' system environment and up t' four instances in virtual operatin' system environments, ye scurvey dog. With VMWare GSX Server, this means ye can run one physical instance plus four virtual instances. With VMWare ESX Server, it means ye can run four virtual instances because there is no need fer a physical instance.

As ye may have noticed from that quote, Microsoft is surprisingly platform agnostic in regards t' which virtualization technology ye choose (MS Virtual Server, VMWare, Xen, etc). Walk the plank! For more information, checkout th' whitepaper pubished last year titled Licensin' Microsoft Server Products with Virtual Machine Technologies. Their indifference may have somethin' t' do with th' many accusations and lawsuits they continue t' face in regards t' their monopolistic power, and a bottle of rum, by Blackbeard's sword! Regardless o' th' reasonin', it’s good news fer everyone.

One rather important thin' t' keep in mind when thinkin' about licensin' Microsoft Server products is that they are licensed per CPU socket, not CPU core, I'll warrant ye. Can ye say “THANK GOODNESS!”? This applies equally t' VMWare ESX – ye need enough HOST licenses o' Windows Server t' cover each physical processor socket in yer ESX cluster.

It’s also important t' keep in mind th' fundamental differences in th' various versions o' Windows Server. Fire the cannons! For example, Server Standard (32-bit) is limited t' accessin' 4GB o' RAM, avast. This would likely be a non-issue fer a guest install, but ye certainly wouldn’t want t' limit yer Host box t' that little memory. Shiver me timbers! It’s not totally scary, just do yer homework and ye’ll be fine.

Microsoft has provided us with this handy little Licensin' Calculator which should help ye make sense o' which version will be right fer ye and yer implementation.

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

If anyone sees an inaccuracy in th' information I’ve provided, please do leave a comment and I’ll update this post accordingly. Thanks t' all th' guys in IRC fer helpin' compile and track down info, specifically, Tony Dye, Chris Green, and David Szpunar.