Method and apparatus for the on-line restoration of a disk in a RAID-4 or RAID-5 array with concurrent access by applications

摘要

A storage system having a plurality of disks arranged in a RAID array with one of said disks being a replacement disk. A method and apparatus for restoring the contents of the replacement disk without interrupting concurrent access to the RAID array. An access request by a user application to a data block in the replacement disk results in regeneration and reconstruction of the accessed data block. In addition, the systematic reconstruction of data or parity blocks not yet accessed by the user application occurs by locating status bits associated with each data and parity block of the new disk.