When more than one device driver can access a drive, tape labels or other data can be overwritten. To prevent possible data integrity issues, you must delete all st device special files for this tape drive.
The operation fails or the drive is temporarily taken offline and is not available for tape operations. The server polls the drive at thirty second intervals to verify that all of the st device special files for the tape drive have been deleted. Once all files have been deleted, the drive is brought back online.
Run the rmstdev utility with -d as the root user to locate and delete the st device special files. Then, retry the operation. For more information about this issue, see the Administrator's Guide in the Information Center.