Multi-version Checkpointing for Flash File Systems

Reliability has become a critical design issue in flash storage systems, because of the adoption of the low-cost, high-error-rate flash chips to fulfill the needs of the fast-growing storage capacity. In this paper, a multi-version checkpointing strategy is proposed to resolve the reliability issue of flash storage systems from the perspective of flash file systems. The proposed strategy can efficiently and effectively utilize checkpoints of file systems to guarantee the integrity and consistency of flash file systems after files or flash pages are corrupted. By utilizing the coexistence fact of multiple versions of the same data in flash memory, a control/recovery mechanism is presented to maintain checkpoints and to recover file systems with minimized management and recovery time overheads. A series of experiments was conducted based on realistic traces that were collected from benchmarks running over flash file systems in Linux operating systems. The results illustrate that the proposed strategy can significantly improve the reliability of flash file systems, as compared with other existing designs.