Patent ID: 7434095

Claim:
A storage system connectable to a computer comprising: a plurality of disk units; and a controller connected to the disk units; wherein the disk units store data in a plurality of data groups and error correcting data corresponding to each of the data groups, wherein the controller performs processing of reconstructing data stored in any of the disk units in which a fault has occurred wherein the controller performs processing of reconstructing data stored in any of the disk units in which a fault has occurred, producing faulty data, on all other data belonging to any based on all other data belonging to any of the data groups to which the data to be reconstructed belongs and error correcting data corresponding to any of the data groups to which the data to be reconstructed belongs, and performs processing of data read/write requests from the computer when a fault has occurred in any of the disk units, and wherein the controller has a plurality of data reconstructing modes including a first mode wherein access or read/write requests from the computer is given preference when the time taken to reconstruct the faulty data is not more than a predetermined time limit, a second mode wherein the data reconstruction processing is given preference when the time taken to reconstruct the faulty data is more than the predetermined time limit, and a third mode wherein the data reconstruction processing is executed based on prepared programs.