Byte-Addressable Update Scheme to Minimize the Energy Consumption of PCM-Based Storage Systems

Abstract

In recent years, phase-change memory (PCM) has generated a great deal of interest because of its byte addressability and nonvolatility properties. It is regarded as a good alternative storage medium that can reduce the performance gap between the main memory and the secondary storage in computing systems. However, its high energy consumption on writes is a challenging issue in the design of battery-powered mobile computing systems. To reduce the energy consumption, we exploit the byte addressability and the asymmetric read-write energy/latency of PCM in an energy-efficient update scheme for journaling file systems. We also introduce a concept called the 50% rule to determine/recommend the best update strategy for block updates. The proposed scheme only writes modified data, instead of the whole updated block, to PCM-based storage devices without extra hardware support. Moreover, it guarantees the sanity/integrity of file systems even if the computing system crashes or there is a power failure during the data update process. We implemented the proposed scheme on the Linux system and conducted a series of experiments to evaluate the scheme. The results are very encouraging.