Query Processing and Execution - SQL Server 2012 Internals and Troubleshooting - page 141

grouping that you created as a “soft” NUMA coni guration. You'll i nd more details on NUMA in
Chapter 3.

Along with the memory nodes created to model the physical hardware of the server, there is
always one additional memory node used by the dedicated administrator connection (DAC). This
ensures that some resources are always available to service the DAC, even when all other system
resources are being used.

On an eight-processor SMP system without soft NUMA, there is one memory node for general
server use, and one for the DAC. This is illustrated in Figure 5-17.

CPU CPU CPU CPU CPU CPU CPU CPU

FSB

Memory
Controller

Main Memory

Node 0

Node 64

FIGURE 5-17

On an eight-processor NUMA system with two nodes of four cores, there would be two memory
nodes for general use, and a third for the DAC. This is illustrated in Figure 5-18.

Local
Memory

Local
Memory

Local
Memory

Local
Memory

Local
Memory

Local
Memory

Local
Memory

Local
Memory

Memory
Controller

Memory
Controller

Memory
Controller

Memory
Controller

Memory
Controller

Memory
Controller

Memory
Controller

Memory
Controller

CPU CPU CPU CPU CPU CPU CPU CPU

Node 0 Node 1

Node 64

FIGURE 5-18