High disk queue values in PerfMon application - IBM System x3755 (Type 8877)

Resolving The Problem

Source

RETAIN tip: H19684

Symptom

High average disk queue length values are seen in the performance monitor (PerfMon) in Microsoft Windows even when the system is idle.

Affected configurations

The system may be any of the following IBM servers:

• System x3755, type 8877, any model

The system is configured with 2 CPU's.

This tip is not option specific.

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

• Microsoft Windows 2003 Server, any service pack
• Microsoft Windows 2003 Server, Enterprise Edition x64, any service pack

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:

• IBM ServerProven

Solution

None.

Workaround

This behavior does not affect the performance of the system but can be prevented by disabling the Power Management of the CPUs when idle. This is achieved in F1 Setup by setting the Processor Power Management in the Advanced Setup/CPU Options to "Disabled". This value is renamed "Low Power Mode on Halt (C1 State)" in BIOS levels beyond 1.01 and is disabled by default in these later code releases.