NUMA function disabled with more than 64 processor cores

Troubleshooting

Problem

When running on systems with more than 64 processor cores, Windows Server 2008 operating systems may incorrectly disable NUMA function within the operating system.

Resolving The Problem

Source

RETAIN tip: H095113

Symptom

When running on systems with more than 64 processor cores, Windows Server 2008 operating systems may incorrectly disable NUMA function within the operating system.

Affected configurations

The system may be any of the following IBM servers:

System x3950 M2, type 7141, any model
System x3950 M2, type 7144, any model
System x3950 M2, type 7233, any model
System x3950 M2, type 7234, any model

The system is configured with at least one of the following:

Microsoft Windows Server 2008, Datacenter 32-bit, any service pack
Microsoft Windows Server 2008, Datacenter 64-bit, any service pack
Microsoft Windows Server 2008, Enterprise 32-bit, any service pack
Microsoft Windows Server 2008, Enterprise 64-bit, any service pack

This tip is not option specific.

The system is configured with 65 CPU's.

Note: This does not imply that the network operating system will work under all combinations of hardware and software.

Please see the compatibility page for more information: http://www.ibm.com/servers/eserver/serverproven/compat/us/

Workaround

Physically remove processor packages until the number of installed cores is equal to, or less than, 64.

Additional information

This is an operating system specific issue.

A fix has been requested from Microsoft.

Limiting the number of processor cores to 64 or less will prevent Microsoft Windows from disabling NUMA functionality.

Document Location

Worldwide

Operating System

System x:Windows Server 2008

System x:Windows Server 2008 x86-64 & 2008 R2

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Tips

NUMA function disabled with more than 64 processor cores - IBM System x3950 M2