Remote copying system and remote copying method

摘要

Composition of a consistency group is changed easily without releasing a volume pair of the consistency group concerning a remote copying system and a remote copying method using a sequence number. In order to change the composition of the consistency group, predetermined data sent from a data sending side after the relevant change is received. At that time, a reflection operation of the predetermined data on a logical storage area is started on a data receiving side after reflection of the predetermined data sent from the data sending side before the relevant change on the logical storage area is terminated.