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arXiv 1509.04764cs.ITcs.CCmath.IT
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Reed-Solomon码的修复

Repairing Reed-Solomon Codes

Venkatesan Guruswami, Mary Wootters

摘要:

本文研究了RS码在分布式存储环境下解决\em精确修复问题\em的性能。我们的主要结果是,在某些参数制度,Reed-Solomon码是最佳再生码,MDS码与线性修复计划。此外,我们给出了MDS码的线性修复计划,在任何参数制度,并可以用来给非平凡的修复计划在其他设置的RS码的一个特征。更确切地说,我们表明,$k$维RS码的评估点是一个有限的字段大小$n$,有确切的修复计划的带宽$(n-1)\log((n-1)/(n-k))$位,这是最佳的任何MDS码的线性修复计划。相比之下,用于该RS码的原始(通常实现的)修复算法具有带宽$k\log(n)$位。当整个字段用作评估点时,节点数$n$远大于每个节点的比特数(即$O(\log(n))$),因此该结果仅在子分组化程度小时成立。然而,我们的方法适用于任何参数机制,为了说明高级别的子分组化,我们为Facebook Hadoop Analytics集群中使用的特定(14,10)-RS代码提供了改进的修复方案。

英文摘要:

We study the performance of Reed-Solomon (RS) codes for the \em exact repair problem \em in distributed storage. Our main result is that, in some parameter regimes, Reed-Solomon codes are optimal regenerating codes, among MDS codes with linear repair schemes. Moreover, we give a characterization of MDS codes with linear repair schemes which holds in any parameter regime, and which can be used to give non-trivial repair schemes for RS codes in other settings. More precisely, we show that for $k$-dimensional RS codes whose evaluation points are a finite field of size $n$, there are exact repair schemes with bandwidth $(n-1)\log((n-1)/(n-k))$ bits, and that this is optimal for any MDS code with a linear repair scheme. In contrast, the naive (commonly implemented) repair algorithm for this RS code has bandwidth $k\log(n)$ bits. When the entire field is used as evaluation points, the number of nodes $n$ is much larger than the number of bits per node (which is $O(\log(n))$), and so this result holds only when the degree of sub-packetization is small. However, our method applies in any parameter regime, and to illustrate this for high levels of sub-packetization we give an improved repair scheme for a specific (14,10)-RS code used in the Facebook Hadoop Analytics cluster.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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