Decreasing failed disk reconstruction time in a RAID data storage system

Failed disk (302) reconstruction time in a RAID storage system is decreased when dealing with non-catastrophic disk failures by using conventional parity reconstruction 216 to reconstruct only that part of the disk that actually failed. The non-failed remainder of the failed disk is reconstructed by simply copying 212 the good parts of the failed disk to the reconstructed copy on a spare drive. Since the good parts of the failed disk are simply copied, it is possible to reconstruct a failed disk even in the presence of disk failures in the secondary volumes (304). The copying and reconstruction starts at the stripe level, but may be carried out at the data block level if a reconstruction error occurs due to secondary media errors.