Volume serial number

The system uses the VOL1 label to ensure that the correct tape is mounted. The volume serial number in the label is compared to the volume serial number that you specify. You can specify the serial number either directly in the DD statement or indirectly through the catalog facility. Serial numbers are required when the processing method is INPUT, INOUT, RDBACK, EXTEND or OUTINX.

Serial numbers are also required when the processing option is OUTPUT or OUTIN with DISP=MOD.

If the volume serial number is correct, the volume is considered to be mounted and verified. If the serial number is not correct, the system rejects the tape and issues another mount message.