Optimal recovery of single disk failure in RDP code storage systems
Optimal recovery of single disk failure in RDP code storage systems
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DOI：
10.1145/1811039.1811054
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发表时间：
2010-06
期刊：
影响因子：
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通讯作者：
Liping Xiang;Yinlong Xu;John C.S. Lui;Qian Chang
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文献类型：
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作者：
Liping Xiang;Yinlong Xu;John C.S. Lui;Qian Chang
现代存储系统使用成千上万的廉价磁盘来满足应用程序的存储需求。为了提高数据可用性，使用了某种形式的冗余。例如，传统的RAID-5系统仅为单个磁盘故障提供数据可用性，而最近的高级编码技术（诸如行对角奇偶校验（RDP））可以为多达两个磁盘故障提供数据可用性。为了降低数据不可用的可能性，每当单个磁盘出现故障时，将执行磁盘恢复（或重建）。我们发现，传统的恢复方案的RDP代码为一个单一的磁盘故障是低效和次优的。本文提出了一种最优的、高效的RDP码单盘故障恢复方案--行对角最优恢复（RDOR），它具有以下性质：（1）读最优，即恢复故障磁盘所需的读次数最少;（2）它具有负载平衡特性，即在重建故障磁盘时，所有幸存的磁盘都将承受相同数量的额外工作负载。我们仔细探讨了设计状态空间，并从理论上证明了RDOR的最优性。我们进行性能评估，以量化的优点RDOR在一些广泛使用的磁盘。
Modern storage systems use thousands of inexpensive disks to meet the storage requirement of applications. To enhance the data availability, some form of redundancy is used. For example, conventional RAID-5 systems provide data availability for single disk failure only, while recent advanced coding techniques such as row-diagonal parity (RDP) can provide data availability with up to two disk failures. To reduce the probability of data unavailability, whenever a single disk fails, disk recovery (or rebuild) will be carried out. We show that conventional recovery scheme of RDP code for a single disk failure is inefficient and suboptimal. In this paper, we propose an optimal and efficient disk recovery scheme, Row-Diagonal Optimal Recovery (RDOR), for single disk failure of RDP code that has the following properties: (1) it is read optimal in the sense that it issues the smallest number of disk reads to recover the failed disk; (2) it has the load balancing property that all surviving disks will be subjected to the same amount of additional workload in rebuilding the failed disk. We carefully explore the design state space and theoretically show the optimality of RDOR. We carry out performance evaluation to quantify the merits of RDOR on some widely used disks.