STORAGE CONTROLLER

PROBLEM TO BE SOLVED: To control an I/O processing from a central processing unit and a connection interruption processing to the central processing unit mutually well- balanced in a storage sub-system under heavy load environment. SOLUTION: In a storage controller connected with the central processing unit by a data transfer path and with plural storage devices to store information, an I/O processing request from the central processing unit for the plural storage devices is queued to the storage controller (20702, 20706 and 20707), a connection interruption request from the storage controller to the central processing unit is queued to the storage controller (20705) and when the I/O processing request and the connection interruption processing coexist in the storage controller, priority is given to the I/O processing request and the connection interruption request and each request is executed according to the priority. In addition, the order of execution is determined by defining an issuing state of the I/O processing request and a processing state of the connection interruption request as judgement factors of giving the priority.