| 摘要 |
PROBLEM TO BE SOLVED: To suppress lowering of the throughput as a total system and to improve system reliability by arranging a system change-over process, so that an apparatus having lighter fault turns into an active system in a method and an apparatus for system change-over, based on the fault levels of a duplex system. SOLUTION: Each apparatus 1-10, 1-20 of an active system and of a stand-by system informs the fault level of its own to the other apparatus via an inter- system link 1-3, and compares the fault level of its own to that of the other apparatus with a fault-level comparison means 1-13, 1-23. Based on the result of the comparison of the fault levels, a system change-over means 1-14, 1-24 changes the system composition, so that the apparatus having a lighter fault level becomes the active system. Furthermore, a fault-level storage means that stores the fault levels just before the system change-over is provided, and by also referring to the stored fault levels of the past stored in the both apparatuses, the system composition is change over, so that the apparatus having a lighter fault level becomes the active system.
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