Improving Energy Effeciency and Reliability of Disk Storage Systems

Abstract

Numerous energy saving techniques have been developed to aggressively reduce energy dissipation in parallel disks. However, many existing energy conservation schemes have substantial adverse impacts on disk reliability. To remedy this deficiency, in this paper we address the problem of making tradeoffs between energy efficiency and reliability in parallel disk systems. Among several factors affecting disk reliability, the two most important factors - disk utilization and ages - are the focus of this study. We built a mathematical reliability model to quantify the impacts of disk age and utilization on failure probabilities of mirrored disk systems. In light of the reliability model, we proposed a novel concept of safe utilization zone, within which energy dissipation in disks can be reduced without degrading reliability. We developed two approaches to improving both reliability and energy efficiency of disk systems through disk mirroring and utilization control, enforcing disk drives to be operated in safe utilization zones. Our utilization-based control schemes seamlessly integrate reliability with energy saving techniques in the context of fault-tolerant systems. Experimental results show that our approaches can significantly improve reliable while achieving high-energy efficiency for disk systems under a wide range of workload situations.