IBM DCS9550 1S1 manual Thermal Control, Power supplies Fitted

Troubleshooting and Problem Solving

4.5.3Thermal 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	The first stage in the	1	Check the installation for any airflow
cool (below 25 °C) and	thermal control process		restrictions at either the front or rear
the fans are observed	is for the fans to		of the enclosure. A minimum gap of
to increase in speed	automatically increase		25mm at the front and 50mm at the
then some restriction	in speed when a		rear is recommended.
on airflow may be	thermal threshold is	2	Check for restrictions due to dust
causing additional	reached. This may be
internal temperature	caused by higher		build-up; clean as appropriate.
rise.	ambient temperatures	3	Check for excessive re-circulation of
Note: This is not a fault	in the local environment
			heated air from rear to the front, use
condition.	and may be perfectly
			in a fully enclosed rack installation is
	normal.
			not recommended.
	Note: This threshold
	changes according to	4	Check that all Blank modules are in
	the number of drives		place.
	and power supplies
	fitted.	5	Reduce the ambient temperature.

IBM System Storage DCS9550 1S1 Storage Expansion Unit Installation, Service, and User Guide 43