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SeeNetBackup Commands Reference Guide.About reading and writing tape filesReading or writing tape files involves copying the file from tape to disk or from diskto tape. To perform read or write operations, use one of the UNIX commands thatperforms input and output operations, for exampletarormt.Themtcommand positions tape files by skipping forward orbackward according to tape marks.The following options are available on the mt command forpositioning tapes:■eof, weofWrites an end-of-file tape mark at the current position onthe tape according to the count option onmt.■fsf, bsfSpaces forward or backward the number of tape markson the count option.■fsr, bsrSpaces forward and backward the number of recordsaccording to the count option onmt. bsris onlysupported for the undefined record type.The following example uses themtcommand to skip forwardthree files on a tape:mt -f tape1 fsf 3Positioning tape filesWhen a file is rewound, it is positioned to the beginning ofthe data. To rewind a tape file, you can use themtcommand.tape1is positioned to the beginning of the tape volume thatis associated with the file.The following command rewinds filetape1:mt -f tape1 rewindThe count option is not used for the rewind operation. If youspecify a count,mtignores it.Rewinding tape files211Reference topicsAbout Tape I/O commands on UNIX
About removing tape filesWhen you have completed reading or writing tape files, use the/usr/openv/volmgr/bin/tpunmountcommand to end the assignment of the tapefile. This command removes from the directory the tape file you created by usingtpreqand removes the tape volume from the tape drive. Thetpunmountcommandis required for each file that thetpreqcommand creates.SeeNetBackup Commands Reference Guide.On UNIX, the NetBackuptpunmountcommand runs thedrive_unmount_notifyscript (if it exists) after media is unmounted.See“drive_unmount_notify script (on UNIX)”on page 170.About external access to NetBackup controlled devices on UNIXThe Media Manager device daemonltidrestricts access to drives that are in anUPstate by changing the permissions of the device files for those drives. Thepermissions are changed to 0600 whenltidstarts and back to their original settingswhenltidis terminated. The permissions also are returned to their original settingswhen a drive’s state is changed toDOWN).Do not modify the permissions of these device files whenltidis active. TheNetBackupavrddaemon periodically tries to rewind and read data from media inthe drives that areUPand are not currently assigned in NetBackup.To ensure reliable operation, do not use UNIX tape and drive commands on thedrives that areUPand controlled byltid. Users can use the NetBackuptpreqandtpunmountcommands and thedrive_mount_notifyanddrive_unmount_notifyscripts on those drives.