The cdi_set_359x_eod program uses mode sense and mode select commands to set a vendor-specific bit in IBM 3590, 3592 and TS1120 tape drives. These drives normally allow a program to read past the typical end of data marks on a tape which may allow a program to recover possibly overwritten data. However, this behavior confuses NetWorker's scanner utility, on some platforms causing a locked-up tape device which may require rebooting or power cycling to restore to normal operation.
If you are going to be using scanner on an IBM 3590, 3592 or TS1120 tape drive you should first run cdi_set_359x_eod to tell the tape drive that it should not allow reading past the end of data.
To restore the default state of the tape drives, you can run cdi_set_359x_eod with the -r flag which will reset (clear) the 'Disable Crossing EOD' bit. Normal NetWorker operations do not seem to be affected by this bit either being set or cleared, so it is not really necessary to reset the bit after using scanner on a particular tape drive.
% cdi_set_359x_eod -f /dev/rmt/47cbn
359x Mode Page 0x25 Disable Crossing EOD bit succesfully SET
% cdi_set_359x_eod -f /dev/rmt/47cbn -r
359x Mode Page 0x25 Disable Crossing EOD bit successfully Reset to default value
% cdi_set_359x_eod -f /dev/rmt/11cbn The drive you are working with (EXABYTE Mammoth2) is not an IBM 3590, 3592 or TS1120.