File-Grain Energy Efficient Buffer Replacement Scheme For Heterogeneous Drive

The storage system is one of the largest energy consumers within computer systems. Hence,reducing the power consumption of storage subsystem becomes an important way for energyconservation in computer system. Much attention has been put on the energy-saving forheterogeneous drive(H-Drive which combines solid-state drive and hard disk drive) recent years.This paper focuses on the combination of solid-state drive(SSD) and hard disk drive(HDD)around the desktop office scenario to find file-grain energy efficient buffer replacement schemefor H-Drive. The main contributions are as follows:1. An energy cost-model for hard disk is proposed.2. Based on the energy-cost model, we adapted the existing online replacement algorithmsFBR and GDS, and proposed an improved scheme called Frequency-Energy Based Replacement(FEBR). We evaluated the effectiveness of existing algorithms on hit rate, energy-efficiency,performance and HDD lifetime.3. By exploiting sliding window, a novel scheme is invented for controlling the on/off timesof hard disk based on probability and statistics.With extensive experiments on four real-world traces, we draw some important conclusions:energy-saving in H-Drive is feasible, it can reach as high as70~80%. FBR and its variant FEBR,and GDS are the best ones among all those online schemes, the energy consumption cost modelcan be used to guide buffer replacement algorithm, and FEBR has some advantage over FBR andGDS; The hard disk controlling scheme works well in protecting the HDD’s lifetime.