Selecting Between Licensing Models

The Enterprise, Standard, and Workgroup Editions of SQL Server provide customers with a choice between a server-CAL licensing model and a per-processor model. (The Web Edition uses the per-processor model exclusively.) Customers should choose carefully between the two models as switching means buying new licenses from scratch. (Starting in early 2009, Microsoft began making a third SQL Server licensing option broadly available—a site license of sorts called an Application Platform Agreement. However, to qualify for such an agreement, a customer would typically need to be spending at least US$100,000 annually on SQL Server, project SQL Server license growth of at least 20% annually, and meet other requirements negotiated individually with Microsoft. For more details, see “Agreement Licenses Servers Enterprisewide” on page 21 of the Feb. 2009 Update.)

As a very general rule, the server-CAL model is cost-effective for installations with small numbers of clients, while installations with large numbers of clients will likely gravitate toward per-processor licensing. This is because a per-processor license for a SQL Server edition is always several times more expensive than the analogous server license to make up for the fact that the per-processor model doesn’t provide Microsoft with client-side licensing revenue.