HP P3410A HP NetRAID 1M/2M Installation & Configuration - Page 135

11 HP NetRAID-2M Battery Backup Unit The Battery Backup Unit preserves data handled by the HP NetRAID-2M adapter by providing protection from power supply interruptions to the HP NetRAID cache memory. The HP NetRAID Battery Backup Unit monitors the voltage level of the DRAM modules installed on the HP NetRAID-2M adapter and supporting circuitry. If the voltage drops below a predefined level, the Battery Backup Unit switches the memory power source from the adapter to the battery pack attached to the adapter. As long as the voltage level is below the predefined value, the HP NetRAID Battery Backup Unit provides the memory refresh cycles necessary to retain the contents of the HP NetRAID-2M memory modules. If the voltage level returns to an acceptable level, the Battery Backup Unit switches the power source back to the HP NetRAID-2M adapter. Charging the Battery The battery pack is shipped fully charged, and it recharges automatically. NOTE The full data retention time is not available unless the battery pack is fully charged. If the battery pack is not charged, set the HP NetRAID cache write policy option to Write-Through while charging the battery pack. After the battery pack is fully charged, you can change the cache write policy to Write-Back. Checking the Status of the Battery Backup Unit The batteries installed in the Battery Backup Unit carry a one-year warranty, but you can expect them to last at least twice that long. The battery life is considered to be "low" if the battery has been through 1,000 recharge cycles. You can check the status of the battery, and the software will warn you if the battery needs to be replaced. To Check Battery Status with HP NetRAID Express Tools 1. Restart the HP Netserver, and press at the prompt to start the HP NetRAID Express Tools utility. 127