| 摘要 |
PURPOSE:To improve an investment effect without decreasing the reliability of the system as a whole by providing at least one spare auxiliary memory device or above for plural computer systems and accessing from each CPU. CONSTITUTION:An auxiliary memory device (bulk) 7 is a spare auxiliary memory device and can access from respective CPUs 1 and 2. When a bulk 3 and a spare bulk 7 are made double, first, the bulk used is indicated, the indicated spare bulk 7 is a slave bulk and the bulk 3 connected to the CPU is a master. Next, after the memory of each CPU is cleared, all contents of a master bulk 3 are copied to a slave bulk 7. Next, indicating information to update the contents of a slave bulk at the time of updating the contents of the master bulk 3, is set, and based upon this, the contents are updated and the contents of both bulks are completely coincident. Thus, the bulk 3 and the bulk 7 are made double and the investment effect can be improved without decreasing the reliability of the system as whole.
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