EMERGENCY ALLOCATION SYSTEM AT THE TIME OF DEFICIENCY OF MAGNETIC DISK DEVICE FOR JOURNAL

摘要

PROBLEM TO BE SOLVED: To avoid deficiency of a magnetic disk device due to copy processing delay in an on-line system for reusing the magnetic disk device by obtaining a journal (history information) for the magnetic disk device and copying the journal to a magnetic tape device. SOLUTION: The on-line system obtains the same journal for the plural magnetic disk devices. Then, when the processing of copying the journal to the magnetic tape device is delayed and the magnetic disk device of a status 24 for alternation is deficient, by turning the other magnetic disk device leaving one in a magnetic disk device group for which the same data are obtained to the status 24 for the alternation from a copy standby status 22, the deficiency of the magnetic disk device of the status 24 for the alternation is evaded.