How It Works: SQL Server 2005 NUMA Basics

I have received several questions on the SQL Server NUMA implementation this week. Much of this was covered in my 2006 PASS presentation in Seattle but allow me to summarize. This is not a complete document by any means but it should be helpful. Hard NUMA: Hard NUMA is the NUMA configuration indicated to the […]

I have received several questions on the SQL Server NUMA implementation this week. Much of this was covered in my 2006 PASS presentation in Seattle but allow me to summarize. This is not a complete document by any means but it should be helpful.

Hard NUMA: Hard NUMA is the NUMA configuration indicated to the operating system by the physical computer.

The following diagram shows a system with 2CPUs per NODE. SQL Server creates a logical scheduler and memory node that matches the hardware configuration. Notice that I have not drawn any specific lines between the logical schedulers (LS) and the physical CPUs. You must use the sp_configure affinity mask values to directly associate a scheduler with a CPU and the affinity mask setting can change the alignment behavior. SQL Server does restrict the schedulers to the same node. LS 1:0 is not allowed to execute on CPU2 or 3 unless the entire node is brought offline.

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Microsoft, SQL Server, NUMA, Knowledgebase, Article