Patent ID: 7152120

Claim:
A remote copy system, comprising: a first storage system including a first storage controller and a first data volume, the first storage controller being configured to receive a write request from a first host associated with the first storage system and to store write data associated with the write request to the first data volume; a second storage system coupled to the first storage system, including a second storage controller, a second data volume and a journal volume, the second storage controller receiving first data containing the write data to copy the stored data in the first data volume to the second data volume; and a third storage system coupled to the second storage system, including a third storage controller and a third data volume, the third storage controller receiving second data from the journal volume, the second data containing a journal to copy the stored data in the first data volume to the third data volume via the second storage system, wherein the journal comprises the write data and a sequence number indicating write ordering to the first data volume; wherein the write request from the first host to the first storage system completes after the first data is received by the second storage system; wherein the write request from the first host to the first storage system completes independently of the second data being received by the third storage system; wherein write data to be stored on the third data volume is generated according to the write order provided by the sequence number of the journal that is contained in the second data.