Self-Adaptive Two-Dimensional RAID Arrays

We propose increasing the survivability of data stored in two-dimensional RAID arrays by causing these arrays to reorganize themselves whenever they detect a disk failure. This reorganization will rebalance as much as possible the redundancy level of all stored data, thus reducing the potential impact of additional disk failures. It remains in effect until the failed disk gets repaired. We show how our technique can be applied to two-dimensional RAID arrays consisting of n² data disks and 2n parity disks and show how it can increase the mean time to data loss of the array by at least 200 percent as long as the reorganization process takes less than half the time it takes to replace a failed disk.