Compaq 3000 - Manual (Page 51)

RAID Array 3000 Controller Shelf
2–18 EK–SMCPQ–UG. C01
2.9 Environmental
The controller incorporates a set of on board sensors to detect abnormal operat-
ing conditions that may affect data safety.
2.9.1 Backup Power Management
The controller must be connected to the Uninterruptable power supply (UPS) to
prevent the subsystem cache from being corrupted during unexpected losses of
power. If no backup power supply is provided, the controller will remain off-line
and reject all I/O requests with a status of Check Condition/Hardware Error.
During normal operation, RAID 3000 ac power is supplied from a line source
through both power cords to both power supplies. Conditions of poor or no power
causes the following UPS responses:
Table 2–5 Response to Various AC Power Conditions
Condition Response
Low line voltage UPS compensation circuit automatically increases out-
put voltage, without placing load on the UPS battery.
No line voltage
(AC loss) UPS switches to the battery which supplies power to the
RAID 3000 maintaining full functionality.
UPS signals RAID 3000 controller of impending power
down. Caching is disabled but the RAID 3000 continues
to service host requests and begins to flush cache to
disk.
UPS low-battery warning UPS signals RAID 3000 controller of impending power
down. Subsystem discontinues host services. Cache
flush is completed.
UPS power down UPS shuts itself off, preventing complete battery dis-
charge. All data has been written to disk.