The present invention is to provide an optical feedback control unit for determining an optical output by a feedback control, an optical communication system, a feedback control method, and a recording medium for recording a program. The display outputs a first input window configured to receive a first message. The apparatus includes a light receiving module to receive a light source, wherein the light receiving module is disposed close to the image sensor module. A Deferred Synchronize Command, specifying a previously supplied transaction, is provided to the tape drive, for writing data of the specified transaction.