Correct Affinity Mask and Affinity I/O Mask Overlap

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This rule checks whether the instance of SQL Server has one or more processors that are assigned to be used with both the affinity mask and the affinity I/O mask options. On a computer that has more than one processor, the affinity mask and the affinity I/O mask options are used to designate which CPUs are used by SQL Server. Enabling a CPU with both the affinity mask and the affinity I/O mask can slow performance by forcing the processor to be overused.

Best Practices Recommendations

When you specify either the affinity mask or the affinity I/O mask options, you should specify both, but only enable each CPU no more than once.

Do not enable the same CPU in both the affinity mask option and the affinity I/O mask option. The bits that correspond to each CPU should be in one of the following states:

  • 0 in both the affinity mask option and the affinity I/O mask option

  • 0 in the affinity mask option and 1 in the affinity I/O mask option

  • 1 in the affinity mask option and 0 in the affinity I/O mask option

For More Information

affinity mask Server Configuration Option

affinity I/O mask Server Configuration Option

affinity64 mask Server Configuration Option

affinity64 I/O mask Server Configuration Option

See Also

Concepts

Monitor and Enforce Best Practices by Using Policy-Based Management