Dell Storage Manager 2020 R1 Administrator's Guide

Internal Backup Power Supply

Each NAS controller is equipped with an internal backup power supply (BPS) that protects data during a power failure. The BPS provides continuous power to the NAS controllers for a minimum of 5 minutes in case of a power failure and has sufficient battery power to allow the NAS controllers to safely shut down. In addition, the BPS provides enough time for the NAS controllers to write all data from the cache to nonvolatile internal storage.

The NAS controllers regularly monitor the BPS battery status, which requires the BPS to maintain a minimum level of power for normal operation. To ensure the BPS battery status is accurate, the NAS controllers routinely undergo battery calibration cycles. During a battery calibration cycle, the BPS goes through charge and discharge cycles; therefore, battery error events during this process are expected. A battery calibration cycle takes up to 7 days to complete. If a NAS controller starts a battery calibration cycle, and the peer NAS controller BPS has failed, the NAS controllers enter journaling mode. Entering this mode might impact performance, so you should repair a failed BPS as soon as possible.