| 摘要 |
PURPOSE:To ensure the continuous use of a system with priority by switching the flag of a system control table and an optical disk medium in case this disk medium has a fault. CONSTITUTION:A data file 1, an index part file 2 and a work file 3 are operated in a system A and an optional one of optical disk media has a fault in the system A. That is, the input/output processing is impossible with the faulty optical disk medium. In such a case, the operation flag of a system control file 7 is changed to a system B from the system A via an updating program 8. Thus each file is operated hereafter by the system B. Then the data files of the optical disk media of the system A are all replaced with those of the system B. Thus each file of the system B is recovered to the state set at a time point when a copy program 6 is executed.
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