Sensitivity Based Power Management of Enterprise Storage Systems

Energy-efficiency is a key requirement in data centers today. Storage systems constitute a significant fraction of the energy consumed in a data center and therefore enterprise storage systems need to deliver high performance in an energy-efficient manner. Static tuning of the storage system is not sufficient since energy consumption is strongly dependent on runtime variations in workload characteristics. Although dynamic disk power management can enable the storage system to adapt to varying workload conditions, prior work in this area has resorted to ad hoc heuristics that cannot guarantee that the system meets energy-efficiency goals. In this paper, we present a novel approach to storage power management that uses the sensitivity-based optimization technique. Our approach systematically balances the dynamic knobs in the disks to operate the storage-system at a desired performance level while maximizing the energy savings. We show that sensitivity-based power management can reduce the energy consumed by the storage system by over 20% for a set of commercial server workloads. We compare sensitivity-based power management to a previously proposed power management scheme for multi-RPM disk drives and show that our approach yields better performance and energy savings.