Quantum Corporation
DLTtape
Application Note
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Copyright 1999-2001 Quantum Corporation or its subsidiaries or affiliates. All rights reserved
DLTtape Tape Drive Use and IRIX Behavior
During periods of non-use of the DLTtape tape drive there is a danger of unintended overwriting of
previously written data. Also, rewinding of DLTtape tape may occur before the next record is read when
the intent is to read the next record at the current tape position. The cause of this behavior is that the IRIX
tape driver unloads from system memory after approximately five minutes of non-use of the tape drive. A
reload of the driver will occur when a command to access the tape drive is requested. During driver
reload, certain initialization tasks occur, one of which is to load a tape cartridge into the drive. For
DLTtape drives, the response to tape load cartridge command when a tape is already loaded is to rewind
the tape. Therefore after a five minute delay of non-use, the DLTtape tape drive will rewind before tape
data access occurs.
To prevent the tape driver from unloading from memory, edit the /usr/var/sysgen/master.d/tpsc file on an
IRIX 5.3 system. For IRIX 6.X, edit /var/sysgen/master.d/tpsc file. Find the line beginning with oscdR
string and change the string to oscdRN. Save and close the file then reboot the system.
DLTtape Mini-Library Usage
The SGI IRIX operating system does not support SCSI-2 media changer device commands. Therefore,
an installed DLT2500/DLT2500XT/DLT2700/DLT2700XT/DLT4500/DLT4700 mini-library can not be
utilized in random access mode and can only be accessed in sequential mode. Refer to either the
DLT2000/DLT2700 product manual, DLT2500 owner's manual, DLT2000XT/DLT2500XT/DLT2700XT or
the DLT4000/DLT4500/DLT4700 product manual for detailed description of these access modes.
