Battery Backup Unit Option

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.

￿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).

☛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.

Manual No. 775012

A-7