How many per-core licenses do I need?
With SQL Server 2012, your licensing requirements can choose to use or be required to use a per-core model depending on the edition you’re deploying. This is a change to previous editions which used a per-CPU socket model that made counting how many per-CPU licences you needed easier – cores and HyperThreading didn’t influence the CPU socket count. Any complications which people did have typically came from running SQL Server in a virtualised environment, was a vCPU a socket or did licensing related to the host’s CPU configuration etc.
SQL Server now shares with us for the first time in 2012 its understanding of the server’s CPU configuration on start-up. In the first few entries in the errorlog you’ll see an entry like these:
SQL Server detected 1 sockets with 4 cores per socket and 4 logical processors per socket, 4 total logical processors; using 4 logical processors based on SQL Server licensing. This is an informational message; no user action is required.
This doesn’t replace the need for accurate licensing purchases based on the hardware architecture you’re deploying but it should at least help you understand what SQL Server’s view of the hardware looks like.