Avago Technologies eXtremeRAID 2000 - Manual (Page 43)

Memory Module and Battery Backup Unit
Manual No. DB11-000028-00 A-3
Maintenance
No maintenance is required. However, we recommend that the BDIMM
charge level be periodically checked using the Gas Gauge function in GAM
please refer to the Global Array Manager Client Software Installation Guide
and User Manual.
Removing the BDIMM
The BDIMM only needs to be removed if the lithium-ion battery no longer
accepts a charge properly (lithium battery life expectancy is approximately
1-1/2 years), or if the BDIMM is being salvaged from a controller that has
failed.

WARNING
For battery service, please contact Mylex or
your authorized dealer for repairs. Batteries
are not user serviceable or replaceable.
BDIMM Functional Description
Whenever the system is running, the BDIMM’s battery backup circuitry is
standing by, monitoring the voltage level supply of 3.3 V. In the event of a
power failure, the supply voltage level will begin to drop. When the battery
backup circuitry detects this voltage drop, it checks the status of the disk
cache. If the cache is empty, the battery backup circuitry does nothing.
If the cache contains data during a power failure, the BDIMM’s battery
backup circuitry 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.