Patent ID: 6886075

Claim:
A method for copying data in a disk array apparatus coupled to a computer, said disk array apparatus comprising m+n disk devices partitioned into a first group of n disk devices and a second group of m disk devices, m and n being different integers: storing data received from said computer in both of said n disk devices of said first group and said m disk devices of said second group for maintaining duplicated data; halting duplicating data based on an instruction from said computer; storing data received from said computer, during interruption of data duplicating, in n disk devices of said first group while recording location information of stored data; restarting data duplicating based on an instruction from said computer; reading data of m−1 units from said first group of n disk devices; forming redundant data based on the data of m−1 units read from said first group of n disk devices; and storing certain data of m−1 units as designated by the recorded location information and said redundant data in said m disk devices of said second group.