Method and controller for defect tracking in a redundant array

Abstract

A disk controller for a disk drive array which maintains two representations of all drive defects. The controller maintains a logical defect list that is used to maintain the sector remapping structure when reconstructing redundancy information. The controller also maintains a physical defect list that is used to preserve known defect information on a physical disk basis. The physical defect list stores the defects even if the logical configuration of the disks changes. When the controller of the present invention determines that a block of data is bad, the controller allocates space for the respective stripe in an alternate block, recovers the data in the stripe and writes the recovered data to the newly allocated stripe. The controller then updates the remap tables in memory with the remap information. On each disk access, the controller searches the logical defect list to determine if the access involves one or more bad blocks. When a failed disk is replaced, the controller rebuilds the data from the failed drive using the remaining data and parity. The controller also uses both the logical and physical defect lists to unmap remapped sectors which were originally remapped due to defective sectors on the replaced disk drive.

Dependencies are inferred from the claim text.