DLT VS80 Tape Drive Reference Guide

Operating System Device Drivers
40 DLT VS80 Tape Drive Reference Guide
HP Tru64 UNIX
The HP Tru64 UNIX operating system uses Dynamic Device Recognition (DDR)
which allows the operating system to recognize the DLT VS80 tape drive.
If the Tru64 UNIX system does not have a DDR entry to identify the DLT VS80
tape drive, the system defaults to a generic SCSI device and to the default settings
of the tape drive.
DDR Recognition
Note: Starting with UNIX 5.1, the syntax for tape related commands changed. The
examples included below show the new syntax.
The DLT VS80 tape drive provides compression so that the storage capability for
tapes can be effectively be doubled. This is known as hardware compression.
Hardware compression should be used instead of the software compression, which
is sometimes provided by software products. The drive is instructed by the user to
turn off hardware compression through use of switches in utilities such as tar.
(Additional information is available online. See the man pages for tz, file,
tar, dump and cpio. Additionally the man page for ddr.dbase can be useful. It
is the derivation for the integers associated with compression below).
The drive defaults to implement hardware compression. In some very limited
cases the drive performance can be improved by turning off hardware
compression.