On 24 Jan 2003 at 5:11pm, Martin Oehler wrote

> I'm sorry, I made a mistake. The hardware compression was off
> all the time. :(
> 
> # mt -f /dev/nrmt0 datcompression 0
> Compression off.
> # mt -f /dev/nrmt0 datcompression 1
> Compression off.

For my AIT drives, I use 'mt compression 0' and 'mt compression 1'.  I 
don't get any sort of feedback from the drive, but I can see the data 
transfer rates change.

> I looked at IBMs ressources, but they offer drivers only for
> RedHat and older SuSE distributions, but I'm using SuSE 8.1 .
> Is it possible that the drive is that slow because I'm using 
> native linux drivers?

What kind of drivers are they offering?  This should all be handled 
through your SCSI driver and st.  What kernel are you using (I'm not 
familiar with SuSE)?

> > >Additionally, I can't understand why the speed is that slow. The
> > > drive should write about 15 MB/sec without HC. Is it possible to
> > > ignore the measured speed and use the one from the datasheet of
> > > the tape?
> > 
> > How fast is the interface?  Maybe it can't to 15 megs a second, 
> > older scsi stuff was hard pressed to do 5 megs, often less.  Much 
> > less.
> 
> The interface is an Adaptec AIC-7899P U160.

Are you sure the bus is operating at LVD?  Remember that any SE devices on 
the bus will drag that whole bus down to SE speeds.

-- 
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University