There is a NBU tape header at BOT which is not (normally) rewritten.
I would simplify Darren's method down to one step by using the bplabel
command (rewriting said header at BOT). It will handle mounting,
writing, etc. Just make sure to do this only on expired tapes of
course.
This assumes that the drive will automatically pick the highest
density when writing to BOT. I'm pretty sure this wasn't the case
when going from 4000 to 7000, but I haven't looked at it in years.
Darren Dunham writes:
> >
> > I am sorry if this was recently covered, but I am still a bit
> > confused. I have some classes which backup highly compressed data using
> > using non-hardware compression. It seems I usually get about 40G/tape,
> > which is right on target, however, many of these tapes used to be used by
> > DLT7000 drives, and it seems that I can't write more than 35G to them:
> >
> > Example
> >
> > DJH558 DLT TLD 0 41 - 3 39195823 FULL
> > DJH582 DLT TLD 0 30 - 2 34462386 FULL
>
> > Do I need to manually override the density for all these tapes, or is
> > there an easier solution?
>
> I don't know the behavior of NB in this situation. It may take a
> recycled tape and forward past a label before doing any writes. If it
> does this, it will never change the density on the tape.
>
> Instead *all* of the tape must be overwritten. Easiest to me would be
> to have a script..
>
> 1) Erase the volume from the NB databases.
> 2) Place the volume in a drive
> 3) mt rewind the volume (guarantee it's at BOT)
> 4) dd if=/dev/zero of=/dev/rmt/Xcbn count=10
> 5) mt offline the volume
> 6) get NB to recognize it as a new tape.
>
> Do you have the lights on the side of your DLT8000s? (some jukeboxes
> don't show the lights). If so, you can verify the density.
>
> You can press the force override density to do this also, but it will
> have no effect if you're writing anywhere other than BOT. So allowing
> NB to mount the tape and then pressing the buttons on the drive may not
> succeed.
>
> --
> Darren Dunham ddunham AT taos DOT
> com
> Unix System Administrator Taos - The SysAdmin Company
> Got some Dr Pepper? San Francisco, CA bay area
> < This line left intentionally blank to confuse you. >
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--
Larry Kingery
Madness takes its toll. Please have exact change.
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