title

Correct affinity mask & affinity IO mask overlap policy

description

Learn how to enable a policy that checks whether an instance of SQL Server has one ore more processors that are assigned to be used with both the affinity mask and the affinity I/O mask options for Policy-Based Management in SQL Server.

author

VanMSFT

ms.author

vanto

ms.date

12/15/2023

ms.service

sql

ms.subservice

security

ms.topic

reference

helpviewer_keywords

Best Practices [Database Engine]

Correct affinity mask and affinity input and output mask overlap

[!INCLUDE SQL Server] This rule checks whether the instance of [!INCLUDEssNoVersion] 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 [!INCLUDEssNoVersion]. 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.

Don't 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: