IBM 084, Инструкция по установке и эксплуатации, Страница: 49 / 78

Thermal monitoring and control
The system uses extensive thermal monitoring and takes a number of actions to ensure that component
temperatures are kept low and also to minimize acoustic noise. Air flows from the front to the rear of the
enclosure.
Symptom
If the ambient air is below 77 °F (25 °C) and the fans are observed to increase in speed, then some
restriction on airflow may be causing additional internal temperature rise.
Note: This is not a fault condition.
Cause
The first stage in the thermal control process is for the fans to automatically increase in speed when a
thermal threshold is reached. This may be caused by higher ambient temperatures in the local
environment and may be perfectly normal.
Note: This threshold changes according to the number of drives and power supplies fitted.
Action
1. Check the installation for any airflow restrictions at either the front or rear of the enclosure. A
minimum gap of 25mm at the front and 50mm at the rear is recommended.
2. Check for restrictions due to dust buildup. Clean as appropriate.
3. Check for excessive re-circulation of heated air from rear to the front. Use of the enclosure in a
fully enclosed rack is not recommended.
4. Check that all blank modules are in place.
5. Reduce the ambient temperature.
Thermal alarm
Symptom
Ops panel module fault LED is amber.
Fan fail LED is lit on one or more cooling modules.
Cause
The internal temperature has exceeded a preset threshold.
Action
1. Check that the local ambient environment temperature is below the specification (see
"Temperature and Humidity").
2. Check the installation for any airflow restrictions at either the front or rear of the enclosure. A
minimum gap of 1 in. (25 mm) at the front and 2 in. (50 mm) at the rear is recommended.
3. Check for restrictions due to dust buildup. Clean as appropriate.
4. Check for excessive recirculation of heated air from rear to the front. Use of the enclosure in a fully
enclosed rack is not recommended.
5. If possible shut down the enclosure and investigate the problem before continuing.
Dealing with hardware faults
Ensure that you have obtained a replacement module of the same type before removing any faulty
module.
Important: Only replace a module when it has been instructed by IBM service. Unplanned replacement of
modules can lead to loss or access of data. When a module is removed for service, replace it immediately.
If the system is used with any modules missing for more than a few seconds, the enclosure can begin to
overheat, causing loss or access of data. This action invalidates the warranty.
Important: Observe all conventional ESD precautions when handling modules and components. Avoid
contact with midplane components and module connectors.
Chapter 5. Troubleshooting 35