Abstract
This paper makes two main contributions. First, it introduces Diverted Accesses, a technique that leverages the redundancy in storage systems to conserve disk energy. Second, it evaluates the previous (redundancy-oblivious) energy conservation techniques, along with Diverted Accesses, as a function of the amount and type of redundancy in the system. The evaluation is based on novel analytic models of the energy consumed by the techniques. Using these energy models and previous models of reliability, availability, and performance, we can determine the best redundancy configuration for new energy-aware storage systems. To study Diverted Accesses for realistic systems and workloads, we simulate a wide-area storage system under two file-access traces. Our modeling results show that Diverted Accesses is more effective and robust than the redundancy-oblivious techniques. Our simulation results show that our technique can conserve 20-61% of the disk energy consumed by the wide-area storage system