Patent ID: 6023780
Filing Date: 2000-02-08
Classification: G06F

Abstract:
A disc array apparatus of RAID level 3 comprising:a plurality of disc drives; anda disc array controlling device controlling data read and write operations by operating in parallel said disc drives, dividing host data input to said disc array controlling device, generating first parity data from the divided data, writing the divided data into disc drives of the plurality of disc drives storing data, and writing said first parity data into one of the plurality of disc drives storing parity of said plurality of disc drives, said disc array controlling device comprising:data write controlling means for adding cyclic redundancy check information to said host data, for dividing the host data including cyclic redundancy check information, and for generating the first parity data from the divided data to control the write operation to each disc drive;parity checking means for generating second parity data from the divided data read from said disc drive, and for performing a parity check by comparing said first parity data with the second parity data read from said disc drive storing parity;host data restructuring means for making a first assumption that, when contradiction is found in comparing of the first parity data with the second parity data during the parity check by said parity checking means, that erroneous data is stored in one of said plurality of disc drives, and for sequentially restructuring, in accordance with the first assumption, the host data from the data stored by the disc drives other than said disc drive assumed to be storing said erroneous data; andcyclic redundancy check information checking means for executing a cyclic redundancy check check on the restructured host data, for, when mismatching is found by the cyclic redundancy check on the restructured host data, changing the assumption of which disc drive is storing erroneous data and repeating the cyclic redundancy check on host data restructured in accordance with the changed assumption, and defining, when matching is attained, host data corresponding to the matching as the correct host data.