A New High-performance, Energy-efficient Replication Storage System with Reliability Guarantee

In modern replication storage systems where data carries two or more multiple copies, a primary group of disks is always up to service incoming requests while other disks are often spun down to sleep states to save energy during slack periods. However, since new writes cannot be immediately synchronized onto all disks, system reliability is degraded. This paper develops PERAID, a new high-performance, energy-efficient replication storage system, which aims to improve both performance and energy efficiency without compromising reliability. It employs a parity software RAID as a virtual write buffer disk at the front end to absorb new writes. Since extra parity redundancy supplies two or more copies, PERAID guarantees comparable reliability with that of a replication storage system. In addition, PERAID offers better write performance compared to the replication system by avoiding the classical small-write problem in traditional parity RAID: buffering many small random writes into few large writes and writing to storage in a parallel fashion. By evaluating our PERAID prototype using two benchmarks and two real-life traces, we found that PERAID significantly improves write performance and saves more energy than existing solutions such as GRAID, eRAID.