Strip-oriented asynchronous prefetching for parallel disk systems  

作　　者：Yang LIU Jian-zhong HUANG Xiao-dong SHI Qiang CAO Chang-sheng XIE 

机构地区：[1]Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China [2]School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China

出　　处：《Journal of Zhejiang University-Science C(Computers and Electronics)》2012年第11期799-815,共17页浙江大学学报C辑（计算机与电子（英文版）

基　　金：supported by the National Basic Research Program(973) of China (No. 2011CB302303);the National Natural Science Foundation of China (No. 60933002);the Fundamental Research Funds for the Central Universities,China (Nos.2012QN100 and 2011TUS-136)

摘　　要：Sequential prefetching schemes are widely employed in storage servers to mask disk latency and improve system throughput. However, existing schemes cannot benefit parallel disk systems as expected due to the fact that they ignore the distinct internal characteristics of the parallel disk system, in particular, data striping. Moreover, their aggressive prefetching pattern suffers from premature evictions and prolonged request latencies. In this paper, we propose a strip-oriented asynchronous prefetching (SoAP) technique, which is dedicated to the parallel disk system. It settles the above-mentioned problems by providing multiple novel features, e.g., enhanced prediction accuracy, adaptive prefetching strength, physical data layout awareness, and timely prefetching. To validate SoAP, we implement a prototype by modifying the software redundant arrays of inexpensive disks (RAID) under Linux. Experimental results demonstrate that SoAP can consistently offer improved average response time and throughput to the parallel disk system under non-random workloads compared with STEP, SP, ASP, and Linux-like SEQPs.Sequential prefetching schemes are widely employed in storage servers to mask disk latency and improve system throughput. However, existing schemes cannot benefit parallel disk systems as expected due to the fact that they ignore the distinct internal characteristics of the parallel disk system, in particular, data striping. Moreover, their aggressive prefetching pattern suffers from premature evictions and prolonged request latencies. In this paper, we propose a strip-oriented asynchronous prefetching （SOAP） technique, which is dedicated to the parallel disk system. It settles the above-n^ntioned problems by accuracy, adaptive prefetching strength, physical data providing multiple novel features, e.g., enhanced prediction layout awareness, and timely prefetching. To validate SOAP, we implement a prototype by modifying the software redundant arrays of inexpensive disks （RAID） under Linux. Experimental results demonstrate that SoAP can consistently offer improved average response time and throughput to the parallel disk system under non-random workloads compared with STEP, SP, ASP, and Linux-like SEQPs.

关 键 词：Parallel disk system STRIP Sequential prefetching Asynchronous scheduling 

分 类 号：TP333[自动化与计算机技术—计算机系统结构]