Storage system and data transfer method

A data transfer method of a storage system including at least one drive chassis having a storage unit and a storage controller connected to the drive chassis, the storage system being connected to a host computer, the method comprising:

• executing a first process for the at least one drive chassis, the first process comprising:
• creating a logical volume having a specified identification name according to an instruction from the storage controller and provides the logical volume to the host computer as a storage area,
• receiving a first read command issued from the host computer to the at least one drive chassis providing the logical volume, and
• transmitting a second command corresponding to the first read command to the storage controller;
• executing a second process for the storage controller, the second process comprising:
• creating a data transfer parameter used for data transfer of the logical address range of the logical volume specified by the second read command, and
• transmitting the created data transfer parameter to the at least one drive chassis;
• executing a third process for the at least one drive chassis, the third process comprising:
• receiving the data transfer parameter from the storage controller,
• reading data from the storage device according to the data transfer parameter,
• transferring the data to the host computer, and
• performing the response,
• wherein the logical volume corresponds to a data storage area protected by the storage controller.