Storage apparatus and method for its control

摘要

A method for controlling a disk control apparatus allows to reduce the number of times to read out information necessary for creating a new value of a parity record from a disk unit and the number of times to write the new value of the parity record into a disk unit. A parity-generation scheduling unit employed in the disk control apparatus reallocates data records in an unallocated status to a logical record in the parity group determined to undergo parity generation, to a logical record allocated to a data record pertaining to a parity group other than the parity group determined to undergo parity generation, if such unallocated data record exist in the parity group determined to undergo parity generation. Later on, the disk control apparatus creates a new value of parity record of the parity group initially determined to undergo parity generation and writes the new value into a disk unit.