Array disk apparatus

Claim 1

An array disk apparatus for dividing serial data and storing the divided data into a plurality of disk units (1-1, 1-2,...1-n, 2) from which said divided data is read and composed into the original serial data, said apparatus comprising: means (3) for dividing serial data into a plurality of divided data; a plurality of data disk units (1-1, 1-2...1-n) for storing said plurality of divided data, one unit accommodating one divided data item; means (3) for generating parity data associated with said plurality of divided data; a parity data disk unit (2) for storing said parity data; means (3) for composing said plurality of divided data into said serial data; means (4) which, if one of said plurality of data disk units develops an error and becomes incapable of storing data or of allowing part or all of the data stored therein to be read therefrom, reconstructs the affected data for storage into said erroneous data disk unit after the repair thereof; means (5) which, if another data disk unit develops a read error during a data reconstruction process, generates "reconstruction unsuccessful" information indicating that the affected data cannot be reconstructed; and means (6) for writing said "reconstruction unsuccessful" information to said erroneous data disk unit whose data is to be reconstructed.