Hitachi NAS Platform 4000 Series Hardware Reference Manual page 37

LEDs
Red If this LED is on immediately after installing a new battery pack, it
indicates that an initial battery charging and conditioning cycle is in
progress. The initial battery conditioning takes approximately 24
hours, and the LED will turn off after the cycle is complete.
If this LED is on during normal operation (not after installing a new
battery pack), either the battery has exceeded its two year life or a
problem has been detected. Check the battery status before
determining any service operation.
Off Normal operation.
LEDs
Red Fan has failed, fan speed is out of acceptable range, or fan speed is
not being reported. (This LED will be on if the corresponding fan has
been removed.)
When on, this LED indicates a failure and that the fan is not operating
correctly. Replace the fan as soon as possible.
Off Normal operation.
Table 7 Hard disk activity and status LEDs
LEDs
Blue If this LED is on and blue, the disk is operating normally and no
problems have been detected. If the LED is flashing blue, it indicates
disk activity. If the LED is on, but not flashing, there is currently no
disk activity.
Red If this LED is on immediately after installing a new hard disk, it
indicates that the RAID configuration for the server is being rebuilt.
The LED will turn off after the RAID configuration is restored. The
amount of time it takes for the RAID configuration to be rebuilt after a
new disk drive is installed depends on the amount of user and system
configuration data stored.
If this LED is on during the course of normal operation (not after
installing a new hard disk), either the disk has failed or the server's
RAID configuration has been degraded.
Chapter 4: Hitachi NAS Platform server components
Hitachi NAS Platform and Hitachi Unified Storage Series 4000 Hardware Reference
Table 5 Battery pack status LED
Meaning
Table 6 Fan status LEDs
Meaning
Meaning
LED status indicators
37