This article by Michael Otey deals with a couple questions about SQL Server 2005 licensing.
The per CPU license is applied per CPU socket, rather than the number of cores. So a server with a single quad-core CPU would need just one license, not four.
When virtualizing SQL Server, the number of CPUs on the host does not matter. You need to license for the number of CPUs the virtual machine (VM) is configured to use. So if you have a host with 4 CPU [sockets], running 3 separate VMs with SQL Server, and each one is configured to use one processor, you would only need 3 SQL Server per-CPU licenses, rather than 4. Conversely, I suppose if you had 5 separate VMs with SQL Server each configured to use one processor, you would need 5 SQL Server per-CPU licenses. And of course, if some of your VMs are using multiple CPUs, that increases the number of licenses needed. For example, in the case with 5 SQL Server VMs, if 3 of those were using 2 CPUs each, then you would need 3×2+2×1=8 SQL Server per-CPU licenses.
Caveats:
- Michael’s article deals with SQL Server per-CPU licensing. There are other licensing options by CAL (client access license).
- This article is now a couple years old, so I would advise checking for yourself on current licensing for SQL Server 2005, as well as 2008.
With that in mind, I’ll add in here links to Microsoft’s SQL Server 2005 and 2008 licensing documentation, in case additional questions arise.
Microsoft SQL Server 2005 Licensing
Microsoft SQL Server 2008 Licensing (Word Doc)
danthedataman.com 