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How much do you really know about SQL Server 2016 licensing?

Should you use Server + CAL licensing for SQL Server 2016 or does Per Core licensing offer more bang for your buck? Read our primer and take this quiz to see if you'd choose right.

Microsoft licensing isn't rocket science; it's much harder. That's why many companies pay software licensing experts to ensure they're doing it right with regards to technologies such as SQL Server.

But even if you outsource licensing compliance, it's smart to have a basic understanding of Microsoft's SQL Server 2016 licensing options. And that's certainly a must if you manage licensing internally.

When Microsoft launched SQL Server 2012, the company shifted its CPU-based server licensing model from measuring physical processors to measuring the cores within those processors. Under Microsoft's Per Core licensing model, each server running SQL Server or any of its components, including SQL Server Integration Services, must be assigned the right number of core licenses. That number varies based on whether customers are licensing physical servers or individual virtual operating system environments (OSEs).

In virtualized environments, one virtual CPU (vCPU) -- or virtual core, in Microsoft's parlance -- equals one core license. To license virtual machines (VMs) for SQL Server 2016, you'll need a core license for each virtual core allocated to a VM, with a four-core license minimum per VM.

In addition, if you want to move those VMs from server to server to allocate resources as needed, you must have Microsoft's Software Assurance maintenance and update program. And, because a virtual core maps to a hardware thread for licensing purposes, you'll need to buy additional licenses if a single thread is tied to multiple cores or vice versa.

Microsoft's Server + CAL licensing model is an alternative option for some SQL Server users. Under it, customers buy a license for each physical server or VM, and each end user or device connecting to a database must have a separate client access license (CAL). By comparison, the Per Core model enables an unlimited number of users or devices to access SQL Server from within or outside of a company's firewall. With Per Core licensing, you don't need to purchase any CALs.

Think you've got it? Test your understanding of SQL Server 2016 licensing with this eight-question quiz. 

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