Microsoft® SQL Server 2012 Unleashed

affinity mask

Type: Advanced option

Default value: 0

When a server is experiencing a heavy load because other applications are running on the same server, it might be desirable to bind thread affinity to a processor.

affinity mask is a bitmapped field that provides SQL Server threads an affinity to processors. This is typically used in conjunction with the affinity I/O mask option just described. Starting from the least-significant digit, each bit that is set to 1 represents the processor on which SQL Server will spawn its threads. Processors are numbered from 0 to 7. An example of the bitmask values for the first seven processors of an eight-processor system follows (with decimal values shown in parentheses):

You usually leave the eighth processor ...