Device-Aware Cache Replacement Algorithm for Heterogeneous Mobile Storage Devices

Abstract. Hard disks, most prevalent mass-storage devices, have high power consumption and high response time for random I/O requests. Recent remarkable technology improvement of flash memory has made it a rising secondary storage device but flash memory still has high cost per bit. Usage of heterogeneous storage devices such as a pair of a hard disk and a flash memory can provide reasonable cost, relatively acceptable response time, and low-power consumption. In this paper, we propose a novel buffer cache replacement algorithm which targets a mobile computing system with a heterogeneous storage pair of a hard disk and a flash memory. The algorithm partitions the cache per each device and adjusts the size of each partition based on the performance indices of the devices, and manages each partition according to workload patterns. Simulations show that the proposed algorithm yields a hit rate up to two times higher than LRU on the typical mobile traces according to the cache size and achieves also better system I/O response time and energy consumption.