:-) Oh, I´m ashamed now, i just noticed when running a "ls -ld /dev/*st0" on my 
system that the *rst* devices don´t even exist
here!!
heheheheheeheh

Thank you everybody. JF sent me an answer that i think is the right one. ( i 
remember i had read something like this some time ago).

> On Fri, Sep 19, 2003 at 04:00:51PM -0300, Bruno Negr?o wrote:
> > Hi guys,
>
> > I?m using a redhat linux to make amanda backups based on tar. Should
> > I use the device /dev/nst0 or /dev/nrst0?
>
> /dev/nst0
>
> > What does the r letter stand for?
>
> On a Unix system, the 'r' stands for 'raw' i.e. don't use the buffer
> cache.  You would use the non-raw device for tasks like mounting a
> filesystem on a tape (read-only, usually), while the raw device gives
> much better performance for normal tape-like activities.
>
> On linux, there generally are no "raw" devices, so the distinction is
> moot.  My Red Hat Linux boxes certainly don't have any *rst*' devices.
>
> -- JF
>