V2-Code: A new non-MDS array code with optimal reconstruction performance for RAID-6

RAID-6 is widely used to tolerate concurrent failures of any two disks in both disk arrays and storage clusters. Numerous erasure codes have been developed to implement RAID-6, of which MDS Codes are popular. Due to the limitation of parity generating schemes used in MDS codes, RAID-6-based storage systems suffer from low reconstruction performance. To address this issue, we propose a new class of XOR-based RAID-6 code (i.e., V²-Code), which delivers better reconstruction performance than the MDS RAID-6 code at low storage efficiency cost. V²-Code, a very simple yet flexible Non-MDS vertical code, can be easily implemented in storage systems. V²-Code´s unique features include (1) lowest density, (2) steady length of parity chain, and (3) well balanced computation. We perform theoretical analysis and evaluation of the coding scheme under various configurations. The results show that V²-Code is a well-established RAID-6 code that outperforms both X-Code and Code-M in terms of reconstruction time. V²-Code can speed up the reconstruction time of X-Code by a factor of up to 3.31 and 1.79 under single disk failure and double disk failures, respectively.