An efficient data layout scheme for better I/O balancing in RAID-6 storage systems

作     者：Ping XIE Jian-zhong HUANG Er-wei DAI Qiang CAO Chang-sheng XIE 

作者机构：Wuhan National Laboratory for Opto Electronics Huazhong University of Science & Technology Computer College Qinghai Normal University 

出 版 物：《Frontiers of Information Technology & Electronic Engineering》 (信息与电子工程前沿（英文版）)

年 卷 期：2015年第16卷第5期

页      面：335-345页

核心收录：

学科分类：0810[工学-信息与通信工程] 0808[工学-电气工程] 0809[工学-电子科学与技术（可授工学、理学学位）] 0839[工学-网络空间安全] 08[工学] 0835[工学-软件工程] 081201[工学-计算机系统结构] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

基　　金：supported by the National Basic Research Program(973)of China(No.2011CB302303) the National High-Tech R&D Program(863)of China(No.2013AA013203) 

主　　题：RAID-6 Data availability High performance I/O balancing 

摘      要：Among redundant arrays of independent disks(RAID)-6 codes, maximum distance separable(MDS)based RAID-6 codes are popular because they have the optimal storage efficiency. Although vertical MDS codes exhibit better load balancing compared to horizontal MDS codes in partial stripes, an I/O unbalancing problem still exists in some vertical codes. To address this issue, we propose a novel efficient data layout, uniform P-code(UPC), to support highly balanced I/Os among P-coded disk arrays(i.e., PC). In UPC, the nonuniformly distributed information symbols in each parity chain of P-code are moved along their columns to other rows, thus enabling the parity chain to keep original parity relationships and tolerate double disk failures. The UPC scheme not only achieves optimal storage efficiency, computational complexity, and update complexity, but also supports better I/O balancing in the context of large-scale storage systems. We also conduct a performance study on reconstruction algorithms using an analytical model. Besides extensive theoretical analysis, comparative performance experiments are conducted by replaying real-world workloads under various configurations. Experimental results illustrate that our UPC scheme significantly outperforms the PC scheme in terms of average user response time. In particular, in the case of a 12-disk array, the UPC scheme can improve the access performance of the RAID-6 storage system by29.9% compared to the PC scheme.