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arXiv · 2412.18430

Calculating the I/O Cost of Linear Repair Schemes for RS Codes Evaluated on Subspaces via Exponential Sums

Zhongyan Liu·Jingke Xu·Zhifang Zhang
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Abstract

The I/O cost, defined as the amount of data accessed at helper nodes during the repair process, is a crucial metric for repair efficiency of Reed-Solomon (RS) codes. Recently, a formula that relates the I/O cost to the Hamming weight of some linear spaces was proposed in [Liu\&Zhang-TCOM2024]. In this work, we introduce an effective method for calculating the Hamming weight of such linear spaces using exponential sums. With this method, we derive lower bounds on the I/O cost for RS codes evaluated on a $d$-dimensional subspace of $\mathbb{F}_{q^\ell}$ with $r=2$ or $3$ parities. These bounds are exactly matched in the cases $r=2,\ell-d+1\mid\ell$ and $r=3,d=\ell$ or $\ell-d+2\mid\ell$, via the repair schemes designed in this work. We refer to schemes that achieve the lower bound as I/O-optimal repair schemes. Additionally, we characterize the optimal repair bandwidth of I/O-optimal repair schemes for full-length RS codes with two parities, and build an I/O-optimal repair scheme for full-length RS codes with three parities, achieving lower repair bandwidth than previous schemes.

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Zhongyan Liu, Jingke Xu, Zhifang Zhang. 2024-12-24. Calculating the I/O Cost of Linear Repair Schemes for RS Codes Evaluated on Subspaces via Exponential Sums. https://arxiv.org/abs/2412.18430

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