Patent ID: 6940666

Claim:
A magnetic tape apparatus comprising: a plurality of magnetic tape drives, and a control unit for reading and writing information from/in the magnetic tape drives by a command from a host computer, wherein said control unit includes: means for storing the same data in the plurality of magnetic tape drives while duplicating the data; means for, when the reading duplicated data from one magnetic tape drive is completed, performing positioning such that a read position of another magnetic tape drive in which the same data is stored is advanced by a length corresponding to an amount of data read from one magnetic tape drive; and means for continuing read of data from the other magnetic tape drive when data is unsuccessfully read from one magnetic tape drive; a master magnetic tape drive, a slave magnetic tape drive; a control unit for reading and writing information from/in the magnetic tape drives by a command from a host computer, wherein said control unit includes: means for storing the same data in the magnetic tape drives while duplicating the data; means for, when the reading duplicated data from the master magnetic tape drive is completed by one block, performing positioning such that a read position of the slave magnetic tape drive is advanced by one block; and means for continuing read of data from the slave magnetic tape drive when data is unsuccessfully read from the master magnetic tape drive; an operation state information storage area of the magnetic tape drives, and the control unit, wherein said control unit includes: means for, when a process to the magnetic tape drive cannot be executed, storing information representing that the magnetic tape drive is unusable in the operation state information storage area; means for reducing the magnetic tape drive in which the unusable information is stored to set the magnetic tape drive in a standby state; and operation state rewriting means for, when the control unit recognizes that a slave magnetic tape drive is in a standby state with reference to the operation state information storage area, reading data from the slave magnetic tape drive, when the data of the slave magnetic tape drive can be read, checking whether or not data in a data block is equal to data in a data block which is being read at the present on the master magnetic tape drive, and rewriting the operation state information of the slave magnetic tape drive into information representing that the data can be read and written when the data are equal to each other.