Hybrid S-RAID: A Power-Aware Archival Storage Architecture

Semi-RAID (S-RAID) is an alternative RAID data layout for applications that exhibit sequential data access pattern in order to reduce power consumption of storage systems. However, it is not design for archival storage specially, and that makes it not much efficient for these applications. In this paper, we present an improved data layout of S-RAID: Hybrid S-RAID (HS-RAID) to improve energy-saving and reliability of the S-RAID used in the archival storage specially. HS-RAID takes two strategies to achieve the goal: one is to storage metadata separating from data files to increase the idle time of disks for energy-saving, the other is to utilize a new parity technique to reduce overheads of the storage system. We have developed a HS-RAID 5 system with 12 hard disks and 2 SSDs to evaluate it. Experimental results show that the power consumption of HS-RAID is only 36% of RAID 5, and 70% of S-RAID 5. Furthermore, the analysis shows that HS-RAID makes average mean time to failure (MTTF) 40 times as long as RAID.