Two New Piggybacking Designs with Lower Repair Bandwidth
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Piggybacking codes are a special class of MDS array codes that can achieve small repair bandwidth with small sub-packetization by first creating some instances of an (n,k) MDS code, such as a Reed-Solomon (RS) code, and then designing the piggyback function. In this paper, we propose a new piggybacking coding design which designs the piggyback function over some instances of both (n,k) MDS code and (n,k') MDS code, when k≥ k'. We show that our new piggybacking design can significantly reduce the repair bandwidth for single-node failures. When k=k', we design piggybacking code that is MDS code and we show that the designed code has lower repair bandwidth for single-node failures than all existing piggybacking codes when the number of parity node r=n-k≥8 and the sub-packetization α<r. Moreover, we propose another piggybacking codes by designing n piggyback functions of some instances of (n,k) MDS code and adding the n piggyback functions into the n newly created empty entries with no data symbols. We show that our code can significantly reduce repair bandwidth for single-node failures at a cost of slightly more storage overhead. In addition, we show that our code can recover any r+1 node failures for some parameters. We also show that our code has lower repair bandwidth than locally repairable codes (LRCs) under the same fault-tolerance and redundancy for some parameters.
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