EMC DS-16B manual Diagnostic Front, Panel Displays, Isolating a System, Fault, Removing Power

		Front Panel Diagnostics
Diagnostic Front	If you suspect a switch or a Fibre Channel port failure, a visual check
Panel Displays	of the color LED Indicators, shown in Figure 4-1, determines the
	status of each port. See Status and Activity Indicators on page 4-4 for
	additional information

	LED Indicators	Power Indicator LED
Figure 4-1LED Indicators
Isolating a System	Various loopback paths are built into the switch hardware for
Fault	diagnostic purposes. A loopback path test within the switch verifies
	the proper internal Fibre Channel port logic functions and the paths
	between the interfaces and central memory.
	The switch’s diagnostics also support external loops which include
	GBIC modules in cross port configurations. These port-to-port
	diagnostics allow checking installed fiber cables and port fault
	isolation.
Removing Power
	Error messages are stored in RAM and are lost when power is removed from
	the switch. Access the error message log to view and note any error messages
	before removing power from the switch.

Front Panel Diagnostics