EOPC: A parallel coding algorithm for XOR-based RAID-6 codes

While inheriting from RAID-6 codes protecting data against two simultaneous disk failures, XOR-based RAID-6 codes are low computational complexity due to only using exclusive-or operations to encode and decode, and are extensively studied and employed in practical. But the potential parallelism of these codes have not yet been sufficiently explored. In this paper, we observe that for XOR-based RAID-6 coding procedures, calculations of parity check equations can be decomposed into pre-calculating and recursive resolution phases. Moreover, these pre-calculating phases of equations can execute in parallel to obtain intermediate blocks that are further used to recursively resolve all missing blocks in a specific sequence. Based on this observation, we present a parallel coding algorithm, called EOPC, for XOR-based RAID-6 codes with the z-turn property, where there exists at least one parity check equation having only one unavailable block under their fault tolerance. We further build EOPC based on two representative XOR-based RAID-6 codes—RDP code and P-Code, to evaluate the effectiveness of EOPC. Experiment results show that EOPC approach outperforms the corresponding serialized approach by more than 50% in encoding/ decoding throughput.