Beyond raid 6 - An efficient systematic code protecting against multiple errors, erasures, and silent data corruption

We describe a replacement for RAID 6, based on a new linear, systematic code, which detects and corrects any combination of E errors (unknown location) and Z erasures (known location) provided that Z + 2E≤4. We investigate some scenarios for error correction beyond the codefs minimum distance, using list decoding. We describe a decoding algorithm with quasi-logarithmic time complexity, when parallel processing is used:≈O(logN) where N is the number of disks in the array (similar to RAID 6). By comparison, the error correcting code implemented by RAID 6 allows error detection and correction only when (E,Z) = (1, 0), (0, 1), or (0, 2). Hence, when in degraded mode (i.e., when Z≥1), RAID 6 loses its ability for detecting and correcting random errors (i.e., E = 0), leading to data loss known as silent data corruption. In contrast, the proposed code does not experience silent data corruption unless Z≥3. The aforementioned properties of our code, the relative simplicity of implementation, vastly improved data protection, and low computational complexity of the decoding algorithm, make our code a natural successor to RAID 6. As this code is based on the use of quintuple parity, this justifies the name PentaRAID^TMfor the RAID technology implementing the ideas of the current paper.

MSC Codes 94B05, 94B35