SAP with Microsoft SQL Server 2005: Best Practices for High Availability, Maximum Performance, and Scalability36
The affinity mask option defines the specific processors on which SQL Server threads can execute. When SQL Server 2005 runs as the dedicated database server or with a SAP application, the affinity mask option uses the default setting of 0.
The 0 setting permits SQL Server threads to execute on all processors. In most situations, the 0 setting provides the best performance because it avoids trapping SQL Server connections on a single processor, while leaving excess capacity on other processors. The 0 setting is used with dedicated database servers and SAP two-tier configurations.
Use the affinity mask option when multiple SQL Server instances and a number of SAP instances run on consolidated hardware. For example:
When multiple instances of SQL Server run on a single server.
To assign each SQL Server instance to particular processes on the server.
The affinity mask option is represented as a binary pattern that is expressed by a decimal number. The affinity mask option settings are shown in the following table.
First processor only
Second processor only
First and second processor only
First four processors
First eight processors
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