Optimizing Cauchy Reed-Solomon Coding via ReRAM Crossbars in SSD-based RAID Systems

Abstract

Erasure codes such as Cauchy Reed-Solomon codes have been gaining ever-increasing importance for fault-tolerance in the SSD-based RAID arrays. However, erasure coding on a processor-based RAID controller relies on Galois Filed arithmetic to perform matrix-vector multiplication, which increases the computation complexity and leads to a huge number of memory accesses. In this paper, we investigate utilizing ReRAM to improve erasure coding performance. We propose Re-RAID which uses ReRAM as main memory in both RAID and SSD controllers, in which erasure coding can be processed on ReRAM. We also propose a confluent Cauchy-Vandermonde matrix as the generator matrix for encoding. By doing this, Re-RAID can distribute the reconstruction tasks for a single failure to SSDs, and then SSDs can recover the data with ReRAM memory. Experimental results show that we can improve the encoding and decoding performance by up to $598 \times $ and $251 \times $, respectively.