| 摘要 |
PURPOSE: To efficiently maintain copied data coherence in a system using optimistic copy by detecting a phenomenon in which the update of copied data is necessary, and adjusting the data reproduction to the copy of all the other reproduction. CONSTITUTION: In a system having plural servers 102, 104, and 106, each server is provided with the reproduction of the arbitrary number of file sets, and each reproduction can be read/written. All operations generating the change of the readable/writtenable reproduced data are inputted to a correction log maintained by non-volatile storage devices 103, 105, and 107. The log recorded operations include operations such as directory preparation, file name change, and directory deletion as the changing operations. A different correction log is maintained for each file set reproduction in a certain server. The changing operations are normally transmitted through a network 118 to the other server, and the other server operates the same correction. Thus, the data coherency between the reproduction can be maintained.
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