Patent ID: 7496718

Claim:
A storage system comprising: a first disk array system coupled to at least one host computer and having a first controller and a plurality of first disk drives, said first disk drives being related to a plurality of first logical volumes; a second disk array system coupled to said first disk array system and having a second controller and a plurality of second disk drives, said second disk drives being related to a plurality of second logical volumes, wherein said first disk array system transmits a copy of a data block to said second disk array system through a communication link based on an update command sent from said host computer, and said second disk array system receives the copy of the data block and stores the copy of the data block into at least one of said plurality of second logical volumes, wherein said first disk array system has a first access control information, which is used to permit or deny an access sent from said host computer to at least one of said plurality of first logical volumes; and wherein said first disk array system sends a copy of the access control information to said second disk array system through the communication link based on a control command sent from said host computer, and said second disk array system receives the copy of the access control information from said first disk array system and permits or denies a received access to at least one of said plurality of second logical volumes by using at least one portion of the copy of said access control information which is less than the entirety of the first access control information.