A Class of MSR Codes for Clustered Distributed Storage
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Clustered distributed storage models real data centers where intra- and cross-cluster repair bandwidths are different. In this paper, exact-repair minimum-storage-regenerating (MSR) codes achieving capacity of clustered distributed storage are designed. Focus is given on two cases: ϵ=0 and ϵ=1/(n-k), where ϵ is the ratio of the available cross- and intra-cluster repair bandwidths, n is the total number of distributed nodes and k is the number of contact nodes in data retrieval. The former represents the scenario where cross-cluster communication is not allowed, while the latter corresponds to the case of minimum cross-cluster bandwidth that is possible under the minimum storage overhead constraint. For the ϵ=0 case, two types of locally repairable codes are proven to achieve the MSR point. As for ϵ=1/(n-k), an explicit MSR coding scheme is suggested for the two-cluster situation under the specific condition of n = 2k.
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