US Patent 7496718 Data transfer and access control between disk array systems

A method for copying information from a first storage subsystem to a second storage subsystem is disclosed. The first and second storage subsystems are provided in a data storage system. The method comprises transmitting first data block from the first storage subsystem to the second storage subsystem, the first storage subsystem being associated with a first host computer and the second storage subsystem being associated with a second host computer; and transmitting first attribute information from the first storage subsystem to the second storage subsystem without intervention from the first host computer.