Acer PCI to Ultra SCSI RAID Controllers DAC960PG - Manual (Page 39)

Battery Backup Unit Option
Manual No. 775012 A-7
Functional Description
General Operational Description
Whenever the system is running, the BBU is standing by, monitoring the
voltage level of VCC. In the event of a power failure, the VCC voltage level
will begin to drop. When the BBU detects this voltage drop, it checks the
status of the disk cache. If the cache is empty, the BBU does nothing.
If the cache contains data during a power failure, the BBU will maintain
cache data integrity until the power is restored. When power is restored and
the system finishes the bootstrap process, the cache contents will be written
to the disk array. The cache contents will then be flushed from the cache.
Status Indication
The status of the battery can be checked with the gas gauge feature that can
be accessed in GAM (version 2.1x or greater). The gas gauge appears on the
screen as two meters, a battery power meter and a charge level meter, each
calibrated from 0 to 100.
The battery power meter indicates the battery capacity in hours. It will
indicate a charge duration of up to 100 hours. The firmware will detect the
Mylex supplied SIMM and assign a value based upon the charge level of the
battery and the power consumption rate of the SIMM.
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Caution
Do not use SIMMs which are not supplied by Mylex.
The charge level meter displays the charge state of the battery expressed in
percent (100% indicates a fully charged battery).
When the meter on the right indicates the battery is fully charged, the meter
on the left will indicate the maximum time in hours that the battery can be
expected to maintain cache data integrity. This value will vary depending
upon which Mylex supplied SIMM is being used (see Table A-1).
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Note
When the charge level is 100%, the current number of
hours and maximum number of hours (printed out
below the left dial) will be equal.