Exploiting In-Memory and On-Disk Redundancy to Conserve Energy in Storage Systems

Today's storage systems place an imperative demand on energy efficiency. A storage system often places single-rotation rate disks into standby mode by stopping them from spinning to conserve energy when the workload is not heavy. The major obstacle of this method is a high spin-up cost introduced by passively waking up the standby disk to service requests. In this paper, the authors propose a redundancy-based hierarchical I/O cache architecture called RIMAC to solve the problem. The idea of RIMAC is to enable data on the standby disk(s) to be recovered by accessing a two-level I/O cache and/or active disks if needed.