NEC S2900 User Manual page 31

(1) POWER LED (green)
The POWER LED lights green if the AC power is supplied and the power switch is set to ON. The
LED is off if the power switch is set to OFF.
(2) SERVICE LED (orange)
The SERVICE LED lights orange when the disk array unit encounters an error. The LED flashes
during the self-test and initialization process that occurs immediately after the power is turned on.
The LED goes off when the disk array unit has started, and it is off while the disk array unit is
operating normally.
(3) Battery cover
Opening the battery cover, you can see two battery backup units installed in the disk array unit.
(4) Battery Backup Units (BBU0/BBU1)
The battery backup units are installed to protect the data remaining in the cache memory at the
occurrence of a power interruption.
See Section 3.3 "Battery Backup Unit" for details.
(5) SHUTDOWN switch
Use this switch to turn off the disk array unit. Using this switch starts writing any cache ddata
remaining in the array controller into disk drive.
To power off the disk array unit, see "7.2 Power On/Off of the Disk Array Unit" for details.
Cached data will be lost if a controller, power supply, or battery is replaced in the following
conditions:
Turning off the Disk Array unit without using the SHUTDOWN switch.
There are not any functioning power supplies supplying power to the array.
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