U indicates that the tape volume indicated on the device is not file protected. That is, a program without RACF® output authorization attempted to use the volume for INPUT only and the tape's file-protection ring is inserted. Therefore, the volume is not completely write protected.
The volume is rewound, the device is unloaded and task waits for the operator to remount the volume or until the task reaches time-out. If a volume is mounted with its file protect ring still inserted, the volume will be unloaded again and the message reissued.
Remove the file-protection ring, remount the volume, and ready the device.
DFSMSdfp
IGC0K05B
3
2