OPTICAL DISK ARRAY LIBRARY DEVICE

PROBLEM TO BE SOLVED: To provide an optical disk array library device of high data and operation reliability. SOLUTION: By connecting or incorporating one or plural RAID controllers 2 to plural optical disk library devices 4 for automatically inserting and withdrawing a medium to/from a data recording and reproducing device 8 by a command from a host and recording and reproducing data and one or plural spare library devices 13 and connecting the spare library device 13 to the RAID controller 2, even in the case that a fault is generated in the library device 4, the data are processed by the RAID controller 2. Also, by providing a mechanism for automatically moving the medium kept in the library device 4 where the fault is generated to the spare library device 13, the restoration processing of the fault is accelerated and the optical disk library system of high reliability for reducing the possibility of system breakdown is realized.