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    一种基于磁盘内和磁盘间冗余的混合编码方案

    A Hybrid Coding Scheme Based on Intra- and Inter-Device Redundancy

    • 摘要: 云计算的发展和应用对存储系统的容错能力提出了更高要求.纠删码被广泛运用于计算磁盘级冗余以抵抗磁盘错误,但抵抗扇区错误时磁盘利用率较低,现有针对扇区错误的优化方案只能抵抗较小数目或者特定分布的扇区错误.为此,利用MDS(maximum distance separable)码的同态性质,提出了一种将磁盘间冗余与磁盘内冗余相结合的混合编码(intra- and inter-device redundancy, IIDR).添加校验磁盘抵抗磁盘错误的同时,在数据磁盘中添加全局校验扇区以抵抗扇区错误,利用磁盘内编码添加本地校验扇区,以优化处理单个扇区错误的性能.最后,正确性证明及性能分析的结果表明所提方案能抵抗磁盘错误和任意分布的扇区错误,并且恢复单个扇区错误计算开销低,更新性能较好,同时与传统的磁盘内编码方案相比,有较高的磁盘利用率.

       

      Abstract: The development and application of cloud computing set higher requirement for the fault-tolerant capability of the storage systems. Erasure code has been widely used to generate device-level redundancy to protect against device failures, while has less space efficiency when resisting the sector failures. Current optimization schemes for the sector failures only resist the failures of small amounts of the sectors or specific sectors. In this paper, we propose a hybrid coding scheme (intra- and inter-device redundancy, IIDR) combining inter-device redundancy with intra-device redundancy based on the homomorphism property of MDS (maximum distance separable) codes, which employs global parity sector against sector failures in the data disks when adding parity device against device failures, and optimizes the ability to process single-sector errors taking advantage of intra-device coding to generate local parity sectors. In the end, the correctness proof and performance analysis are shown in this paper, and the results indicate that our scheme can protect against device failures and sector failures of any distribution, and the computing cost of recovering single-sector errors is much lower, and the update performance is better. Compared with traditional intra-device coding schemes, our scheme comes with less space usage.

       

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