IBM DCS3860, Installation, User'S, And Maintenance Manual

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Seven-segment numeric display LEDs
The seven-segment numeric display LEDs provide information about enclosure
identification and diagnostics. Figure 35 shows the numeric display LEDs and the
heartbeat and diagnostic LEDs.
When you turn on the power to the storage or storage enclosure, the numeric
display LEDs cycle through various codes as the controller or ESM firmware starts
to boot. If the diagnostic LED is illuminated and the heartbeat LED is turned off, it
indicates that diagnostic information is displayed on the numeric display. When
the controller completes the boot process and is operating normally, the diagnostic
LED turns off, the heartbeat LED flashs, and the numeric display changes to show
the enclosure identification (enclosure ID) for that individual enclosure.
If an error occurs during the boot process and the Needs Attention LED is on, the
numeric display shows diagnostic information as sequence of 2-digit diagnostic
code. The number of time each 2-digit code is displayed during a sequence is fixed
and under hardware control. Each sequence minimally consists of a two-digit
category code, followed by a two-digit detail code that is specific to the category.
Longer sequences can be displayed if more than one event is to be reported. This
nominally consists of a series of category-detail sequences with a delimiter
between each category-detail sequence. The entire display goes blank at the end of
the sequence (all segments off, the diagnostic light off), and then the sequence
repeats.
For more information about the diagnostic codes and their possible causes, see the
"Seven-segment display sequence codes and their causes" section of this document.
Cache memory and cache battery
Cache memory size stores read and write operations in the DCS3860 system. Each
storage controller in the DCS3860 storage system contains 12 GB of cache memory
to store read and write operations. In a dual controller configuration, both
controllers in the DCS3860 must have the same amount of cache memory. The
battery unit contains enough charge to back up the cached data in each controller
to a flash drive in the event of a DCS3860 power failure.
A
D
B F
C E
G
SSD 1
D
A
E C
F B
G
SSD 2
DP
DP
Diagnostic Light
Heartbeat Light
Lower Digit Upper Digit
dcsi0038
Figure 35. Numeric display LEDs
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IBM System Storage DCS3860 Storage System: Installation, User's, and Maintenance Guide