A method and system for rapidly recovering data from a failed disk in a RAID disk group are disclosed. According to one aspect of the present invention, a RAID-based storage system identifies a particular disk in a RAID disk group as a "dead" disk (e.g., incapable of servicing client-initiated requests in a timely manner). Accordingly, a spare disk is allocated to replace the "dead" disk and client-initiated read/write requests are directed to the spare disk for servicing. In addition, a disk-to-disk copy operation is initiated. Without overwriting valid data on the target disk with stale data from the "dead" disk, the disk-to-disk copy operation copies data from the "dead" disk to the target by directly reading data from the "dead" disk while reconstructing only the data that cannot be read directly from the "dead" disk.