Hi!
"mt" can turn on and off the hardware compression (take your man to see if it's 
"compression" or "datcompression", it differs from mt versions), but is not 
able to tell you whether the compression is set or not. You just set it on or 
off completely blind.

Take the GNU mt and the Debian patches if you want to get something like :
--- cut here ---
amanda@backup1:~$ bin/mt -f /dev/nst1 datcompression
Compression off.
Compression capable.
Decompression capable.
--- cut here ---
I run a PC Linux RedHat and my mt is from Debian sources (GNU cpio + Debian 
patch) and it works. Thanks Debian :)




On Mon, 6 Oct 2003 11:05:18 -0600
"Amanda Admin" <amanda AT denverdata DOT com> wrote:

> > The "mt" command is supposed to show compression state, but when
> > I attempt this I get nothing. EG.
> >
> > [root] # /bin/mt -f /dev/st0 compression
> > [root] # /bin/mt -f /dev/st0 compression on
> > [root] # /bin/mt -f /dev/st0 compression
> > [root] # /bin/mt -f /dev/st0 compression off
> > [root] # /bin/mt -f /dev/st0 compression
> > [root] #
> >
> > Note the absolute lack of any output after using the command,
> > regardless of whether I try to turn compression on/off or just
> > display compression status. The MAN file for mt says:
> >
> 
> Tony,
> 
> I didn't see in your earlier postings what OS you're running, but I'm
> guessing linux.
> 
> For my Redhat tape-server with HP DAT drives (1 DDS-2, 1 DDS-3) the mt
> command is "mt -f /dev/st0 datcompression". Perhaps that is why you're not
> getting any output from your mt commands when issuing only "compression"?
> 
> BTW, I didn't change my jumper settings either, but I added the following to
> /etc/rc./local to ensure HW compression is off upon a reboot:
> 
> /bin/mt -f dev/st0 datcompression off
> /bin/mt -f dev/st1 datcompression off
> 
> Doug