Abstract: Instead of blocking a storage device low in performance of I/O processing due to execution of restoration processing along with occurrence of a failure of a non-volatile storage element, the storage device is kept used. A storage system comprises storage devices and a storage controller. The storage devices each include a plurality of non-volatile storage elements. The storage devices each is configured to: receive an I/O command from the storage controller; and transmit, when one of the storage devices detects a failure in one of the plurality of non-volatile storage elements that provides a storage area specified by the I/O command as an access destination, a response including a delay occurrence potential notification to the storage controller, the delay occurrence potential notification indicating that, although a possibility of delay in I/O processing exists, continued use of the one of the plurality of storage devices is possible.