tape compression

[C M Reinehr]

On Friday 29 February 2008 06:41, vu pham wrote:
> C M Reinehr wrote:
> [...]
>
> >> Do I have to run any extra command to force the tape drive to use
> >> compression mode ? I already tried "mt -f /dev/st0 compression 1" but it
> >> does not help.
> >
> > What Bill says is very true, but here are some utilities that can be very
> > helpful in figuring out what's going on. The tapeinfo command which comes
> > in the mtx package can tell you explicitly if your hardware data
> > compression is turned on or off. Check out, also, the scsitape command
> > from the same package. Finally, there is the sg3_utils package which
> > contains a number of useful SCSI utilities.
> >
> > Here's what the output of the tapeinfo command looks like on my system
> > with a Tandberg LTO2 tapedrive:
>
> [...]
>
> > By the way, the command that I use to turn compression on & off is:
> > mt -f /dev/nst0 defcompression 1
> >
> > Another thing is that with some tape drives (or so I've read) is that the
> > compression & defcompression commands do not work. You have to set the
> > density code.
>
> CM, thanks for your advice.
> I just installed the package mtx, but it complains that there is no sg
> devices on my server. This server is a RH9. Can I make it see the tape
> drive as sg device ?
>
> Thanks,
>
> Vu

I'm not familiar with RH9 (I switched to Debian some years ago). The /dev/sg* 
entries are created automagically for me by udev now. But, I would imagine, 
if RH9 doesn't use udev, that it simply is a matter of using /dev/MAKEDEV to 
create them.

HTH

cmr

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