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Date:      Mon, 28 Aug 2000 22:15:41 -0700 (PDT)
From:      Matthew Jacob <mjacob@feral.com>
To:        Greg Lehey <grog@lemis.com>
Cc:        Sam <freep@thecity.sfsu.edu>, freebsd-scsi@FreeBSD.ORG
Subject:   Re: "tape is now frozen"
Message-ID:  <Pine.BSF.4.21.0008282211050.36166-100000@beppo.feral.com>
In-Reply-To: <20000829131721.R11422@wantadilla.lemis.com>

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> 
> I've lost the *exact* position.  In fact, I'm not even sure I've lost
> the exact position, but I'm prepared to concede that.  Within a block
> or so I know where I am.
> 

You cannot know that.


> > The whole point of rewind, eom or offline is to bring the tape to a
> > *known* place. Spacing one filemark is not sufficient.
> 
> Why not?  We know we're at the beginning (or end) of a file.

I have fifty files of *almost* identical data. If I think I'm at file 43, but
I'm at file 42, that's wrong. If tape position has been lost, it's been lost.
It's more than a "little bit" pregnant.

It's just barely possible to concede that a (successful) report of hardware
block position could be construed as "setting location". But this also means
that all other notions of file location can not be known any more.

> Well, no, I state it above.
> 
> > It has occurred because there was an I/O error, or you're not using
> > the tape correctly (fixed block mode and you don't issue the correct
> > read size).
> 
> Precisely.  But that's not a reason to penalize people by making them
> wind from one end of the tape to the other.

Argh!!!!! I just plain don't agree, Greg. I'm sorry. If you don't know what
the blocksize is, switch to variable mode. Even then- what's the big deal.
You're not in the middle of the tape- you're at the front of the tape if you
don't know.

I really don't want to change this behaviour. It's wrong to allow people to do
things that would encourage data lossage.

-matt




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