31,673 research outputs found
HFR Code: A Flexible Replication Scheme for Cloud Storage Systems
Fractional repetition (FR) codes are a family of repair-efficient storage
codes that provide exact and uncoded node repair at the minimum bandwidth
regenerating point. The advantageous repair properties are achieved by a
tailor-made two-layer encoding scheme which concatenates an outer
maximum-distance-separable (MDS) code and an inner repetition code. In this
paper, we generalize the application of FR codes and propose heterogeneous
fractional repetition (HFR) code, which is adaptable to the scenario where the
repetition degrees of coded packets are different. We provide explicit code
constructions by utilizing group divisible designs, which allow the design of
HFR codes over a large range of parameters. The constructed codes achieve the
system storage capacity under random access repair and have multiple repair
alternatives for node failures. Further, we take advantage of the systematic
feature of MDS codes and present a novel design framework of HFR codes, in
which storage nodes can be wisely partitioned into clusters such that data
reconstruction time can be reduced when contacting nodes in the same cluster.Comment: Accepted for publication in IET Communications, Jul. 201
Increasing Availability in Distributed Storage Systems via Clustering
We introduce the Fixed Cluster Repair System (FCRS) as a novel architecture
for Distributed Storage Systems (DSS), achieving a small repair bandwidth while
guaranteeing a high availability. Specifically we partition the set of servers
in a DSS into clusters and allow a failed server to choose any cluster
other than its own as its repair group. Thereby, we guarantee an availability
of . We characterize the repair bandwidth vs. storage trade-off for the
FCRS under functional repair and show that the minimum repair bandwidth can be
improved by an asymptotic multiplicative factor of compared to the state
of the art coding techniques that guarantee the same availability. We further
introduce Cubic Codes designed to minimize the repair bandwidth of the FCRS
under the exact repair model. We prove an asymptotic multiplicative improvement
of in the minimum repair bandwidth compared to the existing exact repair
coding techniques that achieve the same availability. We show that Cubic Codes
are information-theoretically optimal for the FCRS with and complete
clusters. Furthermore, under the repair-by-transfer model, Cubic Codes are
optimal irrespective of the number of clusters
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