Patent ID: 7415587

Claim:
A computer system comprising: a first storage system including plurality of physical disk devices, at least one of which is configured to a first logical volume, and providing a first logical volume with a first computer for storing a first data via a network and, a second storage system being coupled to the first storage system via a communication line, including a plurality of physical disk devices, at least one of which is configured to a second logical volume, and providing the second logical volume with a second computer via a network, the second logical volume related to the first logical volume with a second computer, wherein the first storage system transfers, to the second storage system, a second data which is a copy of the first data, and transfers, to the second storage system, a first information related to configuration of the first logical volume when an event related to the first logical volume occurs, the second storage system stores the second data to the second logical volume when the second data is received from the first storage system via the communication line, and changes configuration of the second logical volume related to the first logical volume when the first information is received via the communication line, the configuration change of the second logical volume is performed while maintaining the relation that the data of the first logical volume is copied into the second logical volume and the first logical volume accepts access from the first computer to the copied data after the data of the first logical volume is copied to the second logical volume; and after the configuration of the second logical volume is changed, the data stored in the first logical volume is copied into the second logical volume.