Patent ID: 7228380

Claim:
A storage system that is connected to a computer and another storage system including a first storage device, the storage system provides a logical volume which corresponds to a storage device in the storage system or the another storage system transparent from the computer, the storage system comprising: a first control section that is connected to the computer; a second control section that includes a second storage device that stores data to be used by the computer and a cache memory, and that temporarily stores data from the first control section before storing the data in the second storage device; a third control section that is connected to the another storage system which includes another cache memory for temporarily storing data before storing the data in the first storage device; and an internal network that mutually connects the first control section, the second control section and the third control section, wherein the first control section receives from the computer a first input/output request having first identification information indicative of the logical volume to be accessed, and selects one of the second control section or the third control section based on the first identification information, and sends a second input/output request corresponding to the first input/output request to the second control section or the third control section, and wherein the first control section upon receipt of the first input/output request judges whether a target logical volume to be accessed identified by the first identification information is correlated to the second storage device or correlated to the first storage device and selects an appropriate access destination to the second control section or the third control section based on the judgment.