The beefier your Windows Server license the less copies you'll need for running Microsoft's operating system in virtualized environments.

That's the takeaway of a new Microsoft white paper intended to clarify the company's licensing policy for Windows Server 2003 Release 2 on virtual servers.

Microsoft's paper accompanies an online calculator to help customers estimate the number of licenses they need and to predict the cost of running Standard Edition, Enterprise Edition and Datacenter Edition of the operating system on virtual servers.

Customers running Standard Edition can run just one instance of the operating system in either a physical or virtual environment, with one license per instance. Enterprise Edition customers can run one physical instance and up to four simultaneous virtual instances per processor license, while Datacenter users get an unlimited number of physical or virtual versions of the operating system when licensed per license.

The clarification should benefit users running all vendors virtualization software and comes as Microsoft's own Viridian architecture regresses before our very eyes ahead of Windows Server 2008's launch.

It is unclear how, or whether, Microsoft's policy will change after Windows Server 2008; however, precedent points to a possibly favorable outcome for users. Microsoft's stance has been relatively straightforward unlike, say, IBM and Oracle, who have devised various sets of fractions and power ratings to offset any savings customers might otherwise have gained from running virtualized instances of their products in environments where server numbers have been cut through VMs.

Microsoft has unwittingly found itself on the same side as Red Hat and Sun Microsystems in advocating a per-chip/socket charge in this debate.®

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