Patent ID: 7124267

Claim:
A remote copy system which copies data between a plurality of storage systems, comprising: a first storage system comprising a first controller and a first primary volume; a second storage system comprising a second controller and a second primary volume; a network apparatus which is coupled to a host computer, said first storage system and said second storage system, and which controls a path for accessing from said host computer to said first primary volume and a path for accessing from said host computer to said second primary volume; and a third storage system which is coupled to said first storage system and said second storage system, and which comprises a third controller and a secondary volume; wherein: during remote copying of data stored in said first or said second storage system to said third storage system, said first storage system starts to migrate data stored in said first primary volume in said first storage system to said second primary volume in said second storage system, said first storage system continues to migrates data stored in said first primary volume to said second primary volume in said second storage system during remote copying of data from said first or second storage system to said third storage system, said network apparatus transfers an access request issued from the host computer and destined to said first primary volume, to said second primary volume during said remote copying of data from said first or second storage system to said third storage system, wherein said remote copying of data from said first or second storage system to said third storage system includes, said second storage system receives, from said first storage system, management information for identifying data to send to said third storage system, said second storage system stores write data received from the host computer and the data received from said first storage system and stored in said first primary volume, into said second primary volume, and sends data determined based on said management information out of the data stored in said second primary volume, to said third storage system, said third storage system stores the data received from said first or second storage system, into said secondary volume; and said first storage system completes the migration of data stored in said first primary volume in said first storage system to said second primary volume in said second storage system during remote copying of data from said first or said second storage system to said third storage system.