Bandwidth Adaptive & Error Resilient MBR Exact Repair Regenerating Codes

TL;DR

This paper introduces bandwidth adaptive and error resilient regenerating codes that allow flexible helper node selection and robustness against errors, achieving optimal storage capacity and exact repair in distributed storage systems.

Contribution

It extends existing regenerating codes to be both error resilient and flexible in helper node selection, providing explicit constructions that achieve optimal capacity.

Findings

Derived upper bounds for storage capacity under new assumptions.

Presented explicit coding schemes achieving the bounds.

Extended Product Matrix codes for enhanced flexibility and robustness.

Abstract

Regenerating codes are efficient methods for distributed storage in storage networks, where node failures are common. They guarantee low cost data reconstruction and repair through accessing only a predefined number of arbitrarily chosen storage nodes in the network. In this work we consider two simultaneous extensions to the original regenerating codes framework introduced in [1]; i) both data reconstruction and repair are resilient to the presence of a certain number of erroneous nodes in the network and ii) the number of helper nodes in every repair is not fixed, but is a flexible parameter that can be selected during the runtime. We study the fundamental limits of required total repair bandwidth and provide an upper bound for the storage capacity of these codes under these assumptions. We then focus on the minimum repair bandwidth (MBR) case and derive the exact storage capacity by presenting explicit coding schemes with exact repair, which achieve the upper bound of the storage capacity in the considered setup. To this end, we first provide a more natural extension of the well-known Product Matrix (PM) MBR codes [2], modified to provide flexibility in the choice of number of helpers in each repair, and simultaneously be robust to erroneous nodes in the network. This is achieved by proving the non-singularity of family of matrices in large enough finite fields. We next provide another extension of the PM codes, based on novel repair schemes which enable flexibility in the number of helpers and robustness against erroneous nodes without any extra cost in field size compared to the original PM codes.