Spare disk drive management in a storage system. The storage system comprises disk drives and spare disk drives. Spare disk drives are initially kept in power-off state. The storage system detects the failure of a disk drive and selects a spare disk drive to replace the failed disk drive. The spare disk drive is selected on the basis of spare selection criteria. The selected spare disk drive is powered-on and replaces the failed disk drive. Data on the failed disk drive can be reconstructed on the spare disk drive by using RAID parity techniques.