| 摘要 |
PURPOSE:To reduce the deterioration in the performance of a control part by executing an operation for storing data stored in a current system in a spare system storing part by a copy control part when the space system storing part is incorporated during an operation only by a current system storing part. CONSTITUTION:When the spare system storing part 4 is incorporated during the operation only by the current system storing part 3, the copy control part 5 informs that the spare system storing part 4 is incorporated to the control part 2 through a line 7. At the same time, whether the control part 2 makes access to the current system storing part 3 or not is examined, when it is not made access, the copy control part 5 feeds a read instruction to the current system storing part 3 through a line 8 and feeds a write instruction to the spare system storing part 4 through a line 9. The current system storing part 3 feeds only some blocks of the stored data from a leading part to the spare system storing part 4 through a line 10. The spare system storing part 4 stores the data fed from the current system storing part 3 through the line 10. This operation is repeated until all the data stored in the current system storing part 3 is completely transferred.
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