A Database Management System (DBMS) of a main host system is directed by its
agent
to overwrite database table data (DB table data), which is stored in a DB buffer
and put in and out by the DBMS, to the database table (DB table) on a main disk
unit, and holds the updating of the DB table data in the DB table against a subsequent
request of updating. A main disk control unit is directed by the agent to transfer
the DB table data in the DB table to a DB table on a subordinate disk unit by a
subordinate disk control unit to duplicate the DB table data, and suspend the subsequent
transfer of DB table data so that the DB table data on both disk units are in a
state of matching, thereby enabling the DBMS of the subordinate host system to
refer to the copied DB table.
