To effectively duplex the data again after read and write accesses are given to the data which are preserved as normal backup data in an environment where the same data are held by the disk devices which are controlled by different disk controllers and the data are duplexed.
In this multiplex data storage system, the updated areas of both original and backup data which are updated while the duplexing of these data is interrupted are registered on access information management table 34 of an original disk controller 3. Then the original data corresponding to an access area that occurr 5 while the duplexing of data is interrupted are copied into the backup data based on the information stored in the table 34 when the controller 3 receives a duplexing restart instruction or the backup data are copied into the original data. Thus, the data can be effectively duplexed again.
OZAWA MASAJI
KIMURA YUKIHISA
SUISHU KAZUTO
KANBAYASHI KIMISAKI
NAKAMURA KATSUNORI
