On Fri, Feb 07, 2003 at 07:46:59AM -0500, Joshua Baker-LePain wrote:
> Note, also, that your length is probably rather optimistic.  I've rarely 
> seen hardware compression get the 2X most manufacturers claim (and the 
> 2.6X Sony claims for AIT is truly laughable).  Only you know how 
> compressible your data is, but if amanda keeps banging into EOT, you're 
> going to want to back off on your length.

Good advice.  FWIW, LTO HW compression *does* seem to be pretty good,
though; far better than DLT-4000/7000 and EXB-8500 hardware I've used
in the past (no experience with SDLT or AIT).

Last time I ran a capacity/speed check on my LTO drive using my /home
partition, I got 216GB on a 100GB native tape.  This is a pretty
standard IC engineering /home, lots of e-mail, program source,
executable objects, Verilog source, with a sprinkling of
(uncompressible) gzipped tarballs and simulator waveform output.

On my /project partition (full of Cadence dfII chip database, highly
compressible) it did 249GB.

I use 166GB for my (HW compression) tapetype length; I *hate* hitting
EOT.

-- 
Jay Lessert                               jay_lessert AT accelerant DOT net
Accelerant Networks Inc.                       (voice)1.503.439.3461
Beaverton OR, USA                                (fax)1.503.466.9472