The driving device has a rotatable drive disc that is coupled to a motor and, arranged coaxially with the drive disc, a locking disc that can be rotated to a limited extent relative to the drive disc. Asynchronous remote copying and local replication are also alternately suspended in the conventional system, so that the suspension time increases and the volume in which consistency is obtained becomes old. The second unit does not select the block of 2k word lines, and selects a block of 2k word lines prepared outside the 2n word lines when any one of the 2k word lines among the 2m word lines is defective. The system is configured such that the first reproduction data is identified using pattern recognition, and determination of the second reproduction data is based on the identification of the first reproduction data.