NUMA nodes

What is NUMA?  National Underwater and Marine Agency, (Clive Eric Cussler) and there actually is such a place, although they probably don’t have fleets of ships and a former President who is POTUS.

Non-Uniform Memory Access (NUMA) is a condition where different regions of RAM have different characteristics.  I mean that because RAM is large and there are lots of really fast CPU, addressing one region of memory will take longer than a “closer” region for a particular computer chip.  In this case, it makes sense for a CPU to use memory in it’s neighborhood.  Or more correctly, the data that a CPU is storing and working with is best if it is in one ‘node’ that will be highly accessible to that CPU.

Jonathan Kehayias of PSSkills indicates that this query

select * from sys.dm_os_memory_nodes

will return data like this

memory_node_id virtual_address_space_reserved_kb ... more rows
0              99838476 
64             0

on a non-numa configured machine.  If there are configured numa nodes, there will be more than just two memory_node_id entries.  The second node (64) is the DAC.  You can get a similar view from this

select * from sys.dm_os_nodes

Glenn Berry has a script that gives information about cores and CPUs, et al

-- Hardware information from SQL Server 2012
-- (Cannot distinguish between HT and multi-core)
 SELECT cpu_count AS [Logical CPU Count]
, hyperthread_ratio AS [Hyperthread Ratio]
, cpu_count/hyperthread_ratio AS [Physical CPU Count]
, physical_memory_kb/1024 AS [Physical Memory (MB)]
, committed_target_kb/1024 AS [Committed Target Memory (MB)]
, max_workers_count AS [Max Workers Count]
, affinity_type_desc AS [Affinity Type]
, sqlserver_start_time AS [SQL Server Start Time]
, virtual_machine_type_desc AS [Virtual Machine Type]
FROM sys.dm_os_sys_info WITH (NOLOCK) OPTION (RECOMPILE);
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