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arXiv 1801.09665cs.ITmath.IT
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协作修复:所有容许参数的最优MDS码的构造

Cooperative repair: Constructions of optimal MDS codes for all admissible parameters

Min Ye, Alexander Barg

摘要:

分布式存储系统中多节点修复的两种模型是集中式修复和协作式修复。集中式模型假设所有故障节点都在一个位置重新创建,而协作式模型则规定故障节点可以通信但不同,并且它们之间交换的数据量包含在修复带宽中。作为我们的第一个结果,我们证明了合作修复的最小带宽的下限。我们还表明,合作模式是强于集中式的,在这个意义上说,任何MDS码的最佳修复带宽下的前一个模型也有最佳带宽下的后一个。这些结果是以前已知的额外的“均匀下载”的假设下,这是删除我们的证明。作为我们的主要结果,我们给出了所有可能参数下具有最优合作修复的MDS码的显式构造。更确切地说,给定任何$n,k,h,d$使得$2\le h \le n-d\le n-k$,我们在大小为$|F|\ge (d+1-k)n$的字段$F$上构造$(n,k)$ MDS码,其可以最佳地修复来自任何$d$助手节点的任何$h$擦除。我们的代码的修复方案涉及两轮通信。在第一轮中,每个故障节点从助手节点下载信息,在第二轮中,每个故障节点从其他故障节点下载附加信息。这意味着我们的代码使用尽可能少的轮数来实现最佳修复带宽。

英文摘要:

Two widely studied models of multiple-node repair in distributed storage systems are centralized repair and cooperative repair. The centralized model assumes that all the failed nodes are recreated in one location, while the cooperative one stipulates that the failed nodes may communicate but are distinct, and the amount of data exchanged between them is included in the repair bandwidth. As our first result, we prove a lower bound on the minimum bandwidth of cooperative repair. We also show that the cooperative model is stronger than the centralized one, in the sense that any MDS code with optimal repair bandwidth under the former model also has optimal bandwidth under the latter one. These results were previously known under the additional "uniform download" assumption, which is removed in our proofs. As our main result, we give explicit constructions of MDS codes with optimal cooperative repair for all possible parameters. More precisely, given any $n,k,h,d$ such that $2\le h \le n-d\le n-k$ we construct $(n,k)$ MDS codes over the field $F$ of size $|F|\ge (d+1-k)n$ that can optimally repair any $h$ erasures from any $d$ helper nodes. The repair scheme of our codes involves two rounds of communication. In the first round, each failed node downloads information from the helper nodes, and in the second one, each failed node downloads additional information from the other failed nodes. This implies that our codes achieve the optimal repair bandwidth using the smallest possible number of rounds.

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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