Remote copy system and remote copy method

A computer system control method performed by a primary storage system having a primary volume and a secondary storage system including a secondary volume configuring a volume pair with the primary volume, the method comprising:

• performing, by the primary storage system, collective compression that is collective compression of data of a plurality of journals, wherein
• the collectively compressed data and a plurality of pieces of metadata, corresponding to the collectively compressed data, are transfer targets from the primary storage system to the secondary storage system,
• each of the plurality of journals is configured from journal data and journal metadata which is associated with the journal data, and
• the journal data is a copy of data written in the primary volume;
• and
• acquiring, by the secondary storage system, a plurality of pieces of journal data by decompressing one or more pieces of the collectively compressed data, and writing the plurality of pieces of journal data to the secondary volume.