Patent ID: 7130976

Claim:
A remote copy system comprising: a first storage system having a first storage control unit for controlling data writing in a first logical volume with reference to a first shared memory; and a second storage system having a second storage control unit for controlling data writing in a second logical volume with reference to a second shared memory, wherein the remote copy system stores pair information defining a correspondence relationship between the first logical volume and the second logical volume, in the first shared memory, and information, which, when data is written in the second logical volume, defines a journal volume storing the data and update information of the data, in the second shared memory; wherein when first data is written in the first logical volume, the first storage system issues a write instruction for the first data to the second storage control unit with the second logical volume as an object of writing on the basis of the pair information in the first shared memory, and wherein when a write instruction to write data in the second logical volume is received from the first storage system, with reference to the second shared memory, the second storage system does not write the first data in the second logical volume, but instead writes the first data and update information of the first data in the journal volume if an area defined as the second logical volume is defined as a logical volume area other than the second logical volume, and writes the first data in the second logical volume if the area defined as the second logical volume is not defined as a logical volume other than the second logical volume.