NUMA Concepts and understanding

I am just wondering whether anyone can help me understanding the NUMA on Vmware platform.

I have executed  the below statement on vmware machine which returns two values '0' and '64'

SELECT DISTINCT memory_node_idFROM sys.dm_os_memory_clerks

According to the document on NUMA says '0' indicates it is not a hardware numa.

http://msdn.microsoft.com/en-us/library/ms178144(v=sql.105).aspx

July 3rd, 2013 2:50am

You can view details about the nodes on your server using the sys.dm_os_memory_nodes DMV. You will always have at least one memory node, which has a memory_node_id of 0.You will have more than one memory node if you have configured Non-Uniform Memory Access (NUMA) or if your system uses AMD processors and you have more than four CPU cores.

For NUMA

A non-uniform memory access (NUMA) architecture refers to a system where there the total available memory is broken down into multiple nodes, with groups of processors connecting directly to each node of memory, which is considered the "local" memory pool. Each node also has access to all other memory on the other nodes, which are considered remote or nonlocal memory. NUMA systems are often referred to as ccNUMA, which means cache-coherent NUMA. The cache coherent (cc) part of this term reflects the fact that additional logic is built into the system to ensure that any piece of data is only ever loaded into cache at one place at any point in time.
A NUMA system architecture has the advantage that each processor in a node doesn't pay the cost of using a shared bus to access memory, provided the data it wants is in the local memory pool. If the data it wants is in remote memory, then the cost of getting access to it is a little higher than on an SMP system. Therefore, one of the objectives with a NUMA system is to try to maximize the amount of data that is used from the local memory, and avoid accessing data that is in remote memory.

This text is from Book:Professional SQL server 2008 internals and troubleshooting..please get a copy of this to read in more details

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July 3rd, 2013 4:55am

I am just wondering whether anyone can help me understanding the NUMA on Vmware platform.

I have executed  the below statement on vmware machine which returns two values '0' and '64'

SELECT DISTINCT memory_node_idFROM sys.dm_os_memory_clerks

According to the document on NUMA says '0' indicates it is not a hardware numa.

http://msdn.microsoft.com/en-us/library/ms178144(v=sql.105).aspx

what it is saying is

If SQL Server returns only a single memory node (node 0), either you do not have hardware NUMA, or the hardware is configured as interleaved (non-NUMA). If you think your hardware NUMA is configured incorrectly, contact your hardware vendor to enable NUMA. SQL Server ignores NUMA configuration when hardware NUMA has four or less CPUs and at least one node has only one CPU.

since it returned two rows i think ur hardware is NUMA aware..

July 3rd, 2013 5:06am

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