On Mon, 24 Mar 1997, Max Bell wrote:

> 
> Yes, but old QIC and TK50 (aka DECtape) drives have manual ejects and
> will manage the tape and drive if you try to force an unwound tape to
> eject.  It is also possible to unmount unwound 9-track tapes.  I am
> unaware of any tape media that is designed to be unmounted unless it
> is rewound.  One can easily return to the end of the used portion of
> a tape (assuming it and its device drive are not brain-damaged) by use
> of the "eom" command to `mt`.
>

A very poor design but I do agree it is easy to fine an old possition
just a pain to have to do it.
 
> >nrst0 seems the the better choice to me.
> 
> Since the "State of the Art" (ha) DLT format uses the same manual eject
> mechanism as the old TK50s and both the drive and the tapes are quite
> costly, I do not agree.  If you know what you're doing, just set the
> TAPE environment variable.
> 

Well thats an argument about wether a user will be more educated 
about the tapes they use or the unix they use ?
If they know the tape needs to be reset to the start before ejection
but ends up over writing important data the costs could be considered
worse.

However I must admit I always specify the device and never trust on
the default so it wouldn't make any difference to me.

> >
> >Use the -B option to set the tape size in KB this option is relatively
> >new in dump.
> 
> Yes, and hence does not exist on numerous unix flavors.  It is unwise to
> depend on non-portable options when alternatives (even odd ones) exist.
> 
The rule only applies to a portable product (free or comercial) and
then only if one of the desitination systems does not support the
option. In fact it is often the case that there isn't a common element
between all of the distination systems. In this exmaple many systems
do not use the device /dev/nrst0 and as this a NetBSD mail list the
suggestion of using -B is constructive.
It is folly not to use new more suitable tools. Do you use the
improved 4.4 filesystem format, shadow passwd files, or sendmail
v8.8.x ? The -B option was added to dump because it was long over due.
This option can be found on other Unix installations, IRIX comes to
mind. If someone has to use another version of unix there will be more
drastric changes to deal with than the -B option on dump. 

--Sean