Backup data management method in which differential copy time is taken into account

摘要

Provided is a computer system, comprising a storage system and a management computer. The management computer manages differential copy start times, differential data amounts of first pairs, and a data amount that can be copied in differential copy per unit time; identifies one of the first pairs for which the differential copy is to be started and a start time of the differential copy; subtracts the data amount of differential copy per unit time that is allocated to the identified one of the first pairs from a differential data amount of the identified first pairs; add the unit time to the identified start time; judges that the differential copy has been finished at a time when the subtracted differential data amount reaches zero or less; and calculates time zones in which the first pairs execute differential copy based on the time at which differential copy has been finished.