Storage system, remote copy and management method therefor

A computer system comprising:

• a first computer;
• a second computer;
• a first storage system coupled to said first computer and having a first logical volume for storing first data received from said first computer;
• a second storage system coupled to said second computer and having a second logical volume for storing second data received from said first computer;
• a third storage system receiving said first data from said first storage system and having a third logical volume for storing replication data of said first data;
• and
• a fourth storage system receiving said second data from said second storage system and having a fourth logical volume for storing replication data of said second data;
• wherein said second computer is coupled to said third storage system,
• wherein said second computer manages a first copy pair of said first logical volume and said third logical volume and a second copy pair of said second logical volume and said fourth logical volume, transmits a group control instruction to said third storage system for controlling a replication process by using said first copy pair and said second copy pair as a copy group, and
• wherein, in response to said group control instruction, said third storage system transmits a replication status inquiry to said first storage system and said second storage system, said replication status inquiry inquiring about a status of said replication process, and manages a status of said copy group in accordance with said status of said replication process.