SmartBackup : an efficient and reliable backup strategy for solid state drives with backup capacitors

摘要

Unpredictable power outages in NAND flashbased Solid State Drives (SSDs) may cause system failure or reliability problems. Capacitors are widely adopted as the interim power supplier when power interruption happens. However, since the energy provided by backup capacitors is limited, and the capacitance of a capacitor will gradually degrade with time, it is imperative to improve the efficiency and reliability of the backup process for SSDs with capacitors. This paper presents a novel backup scheme called SmartBackupfor MLC NAND flash-based SSDs with backup capacitors. In SmartBackup, by exploiting the feature of the discharge process of capacitors, all available SSD channels are fully utilized and dynamically adjusted based on the available voltage, so data can be efficiently stored in a reliable manner. Moreover, in SmartBackup, to write data in a time/energyefficient manner with better reliability, we adopt a fast and reliable programming strategy by only writing LSB (Least Significant Bit) pages in MLC NAND flash. To the best of our acknowledge, this is the first work to jointly utilize the property of the multi-page architecture of MLC NAND flash and the discharge characteristic of capacitors to improvethe efficiency and reliability of the backup process in SSDswith backup capacitors. The experimental results show thatSmartBackup can effectively accelerate the backup processand improve the reliability.