A RAID controller performs a preemptive reconstruct of a redundant array of disks while it is still fault-tolerant by determining the errors by a first disk exceeded the error threshold, and reading data from a second disk, and writing the data to a spare disk. The second disk's data is a mirrored copy...http://www.google.com.hk/patents/US7313721?utm_source=gb-gplus-share專利 US7313721 - Apparatus and method for performing a preemptive reconstruct of a fault-tolerant RAID array
