| 摘要 |
PURPOSE:To hold a state of an auxiliary storage device without using a special hardware, by setting an on-line/off-line state of the auxiliary storate device to a control table in accordance with contents of a history counter part. CONSTITUTION:At the time of installation, history counter parts 40, 41 in sub- units 20, 21 are initialized, and the units 20, 21 are in an on-line state. In case when the unit 20 is detached in this state, a CPU 60 updates a control table 80 on a main memory 70, sets the unit 20 to an off-line state, and updates contents of the counter part 41. When the unit 20 is incorporated again, the CPU 60 makes contents of the counter part 40 coincide with contents of the unit 21. In this case, the CPU 60 updates the control table 80, and sets the unit 20 to the on-line state again. In this way, a state of each sub-unit is held without using a special hardware, and when restarting, the state of each sub-unit before stop can be reproduced exactly. |
