| 摘要 |
PROBLEM TO BE SOLVED: To avoid the closure for all paths due to a path closure switching operation, when plural paths provided for redundancy or multiplexing or the like break down. SOLUTION: A disk controller 100 is connected through an input and output path 280, constituted of plural paths 0-n with a storage device group 170. The number of times of errors (A) for each of the paths 0-n detected by an error- detecting circuit 150 is individually counted by a counter circuit 140, and a closure condition threshold B set in a memory 120 is compared with the number of times of errors (A) of each path by a comparator 130, and when A>B, the path is closed and switched to another path so that path-switching control can be realized. In this case, the path closure condition is relaxed by gradually increasing the closure condition threshold B set in the memory 120 according to the decrease of the residual healthy paths. Thus, system-downs due to the closure of all the paths 0-n can be avoided. Also, the residual path, in which the accumulated number of error times or the frequency of errors is smaller, is preferentially selected so that path failures are hardly generated.
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