Sacrificing Reliability for Energy Saving: Is it worthwhile for disk arrays?

Mainstream energy conservation schemes for disk arrays inherently affect the reliability of disks. A thorough understanding of the relationship between energy saving techniques and disk reliability is still an open problem, which prevents effective design of new energy saving techniques and application of existing approaches in reliability-critical environments. As one step towards solving this problem, this paper presents an empirical reliability model, called Predictor of Reliability for Energy Saving Schemes (PRESS). Fed by three energy-saving-related reliability-affecting factors, operating temperature, utilization, and disk speed transition frequency, PRESS estimates the reliability of entire disk array. Further, a new energy saving strategy with reliability awareness called Reliability and Energy Aware Distribution (READ) is developed in the light of the insights provided by PRESS. Experimental results demonstrate that compared with existing energy saving schemes, MAID and PDC, READ consistently performs better in performance and reliability while achieving a comparable level of energy consumption.