> Of course hardware compression has one big advantage: speed.  If you
> have to fit lots of data in a small backup window at night, and your 
> cpu's are not fast enough, or interfere with the nightly cpu-intensive
> jobs, then hardware compression is the way to go.


I have to take issue with this. My experience with hardware
compression on DDS and DLT drives is that when enabled it makes things
incredibly slow.

My DLT IV (er, 7000?) drives can do 4.9 MB/s uncompressed, and only
800KB/s in compressed mode.

I have to seriously believe that the hardware compression ratio could
easily be surpassed by a modestly fast host performing software
compression. Also with Amanda doing it, it'll already be compressed on
the holding disk before streaming to tape.

Yet another reason I use client side compression.

Russell