ed. Image files from a graphical program like Paint may compress at
4.5:1 or more, while binary files may compress at just 1.5:1. Data
that has already been compressed or random data (such as encrypt-
ed data) may actually expand by about five percent if you attempt
to compress it further. This can actually reduce drive throughput.
Mixing Density.
Your DLTtape system can easily mix compression
ratios on a single tape. Compression will change on the fly depend-
ing on the input data. If the tape was used previously at another
density setting, you can overwrite data at a different density (if the
tape supports it) at any time with the Density Override button on
the drive’s front panel.
Backwards, Not Forwards.
We have been very careful in developing
each generation of DLTtape system to ensure backward compatibili-
ty with previous generations. For example, the SDLT 220 Super
DLTtape drive can read files on DLTtape IV cartridges at 20, 35, or
40GB native capacity. The DLT 8000 drive can read and write files
on DLTtape III, DLTtape IIIXT, or DLTtape IV cartridges at 10, 15,
20, 35, and 40GB native capacity. This provides you with excellent
investment protection in both media and drive technology. It should
be noted that the reverse is not necessarily true. For instance, a
DLT 260 drive (the first DLTtape drive) with a maximum native
capacity of 2.6GB can only read DLTtape media recorded at 2.6GB.
In other words, a DLTtape drive cannot read a tape recorded at a
density higher than it is capable of recording at. A DLT 2000 drive,
for instance, has a maximum native capacity of 10GB, so it can read
DLTtape cartridges written at 10, 6, and 2.6GB, but nothing higher.
Resources For You
We hope these tidbits of DLTtape drive wisdom will come in
handy some day. Remember, you can always call the Quantum
Service Center at (408) 894-4000, visit the Quantum Web site at
QUANTUM DLTtape HANDBOOK
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