The Sun Flash Accelerator F20 PCIe card contains a component called the energy storage module (ESM) that functions similarly to a battery backup. The ESM plays a critical role protecting data during power outages and enabling optimal card performance. When the ESM is online and functioning properly, the card operates in write-back mode (providing optimal performance). When the ESM is not functioning properly, the card functions in write-through mode. While data is secure in write-through mode, performance is dramatically decreased.
Based on the expected life of the ESM, and to maintain optimal card performance, replace the ESM every three years. If the ESM is not replaced at the recommended service interval, the level of stored energy degrades over time. If there is not enough stored energy to complete a write operation during a power failure, any data stored on the card is at risk of being lost.