Comparison of RAID-6 Erasure Codes

International audienceCoding techniques for RAID-6 storage systems, providing a doublefault-tolerance, are varied. They all come with their respective benefits andlimitations. In this paper, we compare the characteristics of five prominenterasure codes. We show that the general-purpose Reed-Solomon codes, eitherbased on Vandermonde or Cauchy matrices, are outperformed by Array codes (i.e.EVENODD, RDP) which are specifically designed for RAID-6 storage systems.However geometrical codes such as the Mojette erasure code show evenbetter performances at the cost of a slight extra storage overhead. We outlinethe differences between these codes in terms of encoding, updating and decodingcomplexity. We believe that such an analysis can be valuable to systemdesigners to figure out which code would best suit their requirements