Information storage system

摘要

By assuring and maintaining consistency of data within a range expected by the user, significance of the consistency of data is assured. A master control unit 105 to which write data and its write time is transferred from an information processor 100 is provided with a function of obtaining the latest write time and the oldest write time of write data which has not been copied to each of remote control units 115 as a copy destination at proper timings and comparing the difference between the latest and oldest write time with a preset time on the basis of a data consistency unit such as a data set. When the difference reaches or exceeds the preset time, data within the data consistency assuring range is suspended or write data and copy data is regulated.