Hybrid S-RAID: An Energy-Efficient Data Layout for Sequential Data Storage

Power consumption of storage systems can not be ignored any more with the increment of the scale of storage systems, and the research in energy-saving of storage systems becomes more important. A data layout for storage systems in order to reduce power consumption is proposed in this paper: Hybrid S-RAID (HS-RAID). HS-RAID includes two parts: one is RAID 1 which is composed of two SSDs, and the other is S-RAID that is composed of a group of hard disks. Hard disks are grouped in S-RAID, and parallel in the group. Remapping the random I/O requests on the RAID 1, sequential data I/O write on the S-RAID by the group order. When only one group of hard disks are busy under continuous data access mode, the others can be shut down or put into standby mode for energy-saving because of no requests on them. That can save energy in HS-RAID and only increases the cost of the storage system slightly. HS-RAID is designed for applications whose I/O characteristics are sequential access. Experiment shows that the HS-RAID with 12 hard disks and 2 SSDs consumes 28% power of such a RAID 5 system.