IBM DCS9550 1S1 - Manual (Page 58)

Troubleshooting and Problem Solving
IBM System Storage DCS9550 1S1 Storage Expansion Unit Installation, Service, and User Guide 43
4.5.3 Thermal Control
The DCS9550 1S1 Storage Expansion Unit uses extensive thermal monitoring and takes a
number of actions to ensure component temperatures are kept low and also to minimize
acoustic noise. Air flow is from front to rear of the enclosure.
Symptom Cause Action
If the ambient air is
cool (below 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. 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. 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
build-up; clean as appropriate.
3 Check for excessive re-circulation of
heated air from rear to the front, use
in a fully enclosed rack installation is
not recommended.
4 Check that all Blank modules are in
place.
5 Reduce the ambient temperature.