SQL Server not using all cores I have a server with 6 cores, I've installed SQL Server 2012 web edition, based on core licensing, allowing up to 16 cores.
However, it only uses 4 cores.
In the error log file:

2015-07-09 14:00:32.52 Server      Microsoft SQL Server 2012 (SP1) - 11.0.3128.0 (X64) 
Dec 28 2012 20:23:12 
Copyright (c) Microsoft Corporation
Web Edition (64-bit) on Windows NT 6.2 &lt;X64&gt; (Build 9200: ) (Hypervisor)
2015-07-09 14:00:32.70 Server      SQL Server detected 6 sockets with 1 cores per socket and 1 logical processors per socket, 6 total logical processors; using 4 logical processors based on SQL Server licensing. This is an informational message; no user action is required.


Should I define something else to use all cores?

Thank you.
The problem was with the VM provider.
Sql Server 2012 Web license states it's limited to 4 sockets or 16 cores, so if you want to use 16 cores you need a machine with 4 sockets that have 4 cores each.
In my case I had 6 sockets with one core each, that's why only 4 were usable.

Hope this helps future developers facing a similar problem.