TRIP: Temporal Redundancy Integrated Performance Booster for Parity-Based RAID Storage Systems

Parity redundancy is widely employed in RAID-structured storage systems to protect against disk failures. However, the small-write problem has been a persistent root cause of the performance bottleneck of such parity-based RAID systems, due to the additional parity update overhead upon each write operation. In this paper, we propose a novel RAID architecture, TRIP, based on the conventional parity-based RAID systems. TRIP alleviates the small-write problem by integrating and exploiting the temporal redundancy (i.e., snapshots and logs) that commonly exists in storage systems to protect data from soft errors while boosting write performance. During the write-intensive periods, TRIP can reduce the penalty of each small-write request to as few as one device IO operation, at a minimal cost of maintaining the temporal redundant information. Reliability analysis, in terms of Mean Time to Data Loss (MTTDL), shows that the reliability of TRIP is only marginally affected. On the other hand, our prototype implementation and performance evaluation demonstrate that TRIP significantly outperforms the conventional parity-based RAID systems in data transfer rate and user response time, especially in write-intensive environments.