>That's what I had figured, you can't compress compressed data, I wonder
>does this have any performance affect though?

Yes, in that you won't be able to write to the drive any faster than its
uncompressed (native) transfer speed.  For drives that do compression, you
can send data into a drive at a higher rate than the actual tape drive
mechanism can write, because the data is compressed (and, therefore, there's
less of it) by the time the data actually reaches the tape.

One other thing to check: if you are using Solaris, or another operating
system where you must select the appropriate device special file to enable
compression, make sure you are using the /dev/rmt/0cbn device special file,
rather than /dev/rmt/0bn.

tl

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