Light Path Diagnostics; Viewing The Light Path Diagnostics Leds - IBM BladeCenter JS21 Types 8844 Service Manual

Light path diagnostics

Light path diagnostics is a system of LEDs on the control panel and on the system
board of the blade server. When an error occurs, LEDs are lit throughout the blade
server. By viewing the LEDs in a particular order, you can often identify the source
of the error.
The system board LEDs can be lit for a short time after you remove the blade
server from the BladeCenter unit. After removing the blade server cover, press and
hold the light path diagnostics switch for a maximum of 25 seconds to light the
LEDs. Power remains available to light these LEDs for up to 24 hours after the
blade server is removed from the BladeCenter unit. These LEDs include error LEDs
for the following components:
v Microprocessors
v Memory modules (DIMMs)
v Hard disk drives
v I/O expansion option

Viewing the light path diagnostics LEDs

Before working inside the blade server to view light path diagnostics LEDs, read the
safety information that begins on page vii and "Handling static-sensitive devices" on
page 142.
If an error occurs, view the light path diagnostics LEDs in the following order:
1. Look at the control panel on the front of the blade server (see "Blade server
2. To view the light path diagnostics panel and LEDs, complete the following steps:
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BladeCenter JS21 Types 7988 and 8844: Problem Determination and Service Guide
control panel buttons and LEDs" on page 4).
v If the information LED is lit, it indicates that information about a suboptimal
condition in the blade server is available in the management-module event
log.
v If the blade-error LED is lit, it indicates that an error has occurred; go to step
2.
a. Remove the blade server from the BladeCenter unit.
b. Place the blade server on a flat, static-protective surface.
c. Remove the cover from the blade server.
d. Press and hold the light path diagnostics switch to relight the LEDs that
were lit before you removed the blade server from the BladeCenter unit. The
LEDs will remain lit for as long as you press the switch, to a maximum of 25
seconds.