A Generic Transformation to Generate MDS Array Codes With δ-Optimal Access Property

Recently, some high-rate maximum distance separable (MDS) array codes were designed to optimally repair a single failed node by connecting all the surviving nodes. However, in practical systems, sometimes not all the surviving nodes are available. To facilitate the practical storage system, a few constructions of $(n,k)$ MDS array codes with the property that any single failed node can be optimally repaired by accessing any $d$ surviving nodes (i.e., minimum-storage regenerating (MSR) codes) have been proposed, where $d\in [k+1:n-1)$ . However, all high-rate MDS array codes with this property either have large sub-packetization levels or are not explicit for all the parameters. To address these issues, we propose a generic transformation that can convert any $(n',k')$ MDS array/scalar code to another $(n=n'-\delta,k=k'-\delta)$ MDS array code with the optimal repair property and optimal access property for an arbitrary set of two nodes, while the repair efficiency of the remaining $n-2$ nodes can be kept, where $2\le \delta \le n'-k'$ . By recursively applying the generic transformation to an MDS scalar code multiple times, we get a high-rate MDS array code with the optimal repair property and the optimal access property for all nodes, which outperforms previous known high-rate MDS array codes in terms of either the sub-packetization level or the flexibility of the parameters.