Actually I am having a good laugh at this conversation.
Has anybody actually observed what automedia verify really does ?
I suggest you take a chair next to the drive, load nwadmin, and wait for it
to happen.
You will be supprised.

Bye
Ernie

----- Original Message -----
From: "George Sinclair" <George.Sinclair AT NOAA DOT GOV>
To: <NETWORKER AT LISTMAIL.TEMPLE DOT EDU>
Sent: Friday, May 07, 2004 5:27 PM
Subject: Re: [Networker] Auto media verify?


> Hard to believe all the threads that my original posting has produced.
> LOL! Sometimes you never know all the responses that will be generated.
> But, now that we've been on this subject of DLT drives, and whether or
> not they benefit from this media verification safety net option, or
> whether it's moot, does anyone know the scoop on LTO? Do LTO drives have
> this problem?
>
> George
>
> Steve Rader wrote:
> >
> >  > > DLT (and most all modern tape technologies, IIRC) do "read after
> >  > > write", so DLT drives automatically verify that all the data they
> >  > > receive is written to tape.  That leads me to think that auto media
> >  > > verify is not necessary, at least when writing to DLT.
> >  > >
> >  > > So I'm still left wondering: is there some compelling reason
> >  > > to set auto media verify?  (If the answer is yes, I would think
> >  > > Legato would make it a default setting or at least mention it in
> >  > > doc/release notes.)
> >
> >  > The question is, does DLT (or other technology) acknowledge the write
> >  > before or after verifying the tape.  If it's before the verification,
> >  > then a situation could arise where the verification fails and there
is
> >  > not enough tape left in the cartridge to rewrite the buffer.  I'll
bet
> >  > that is the case.
> >
> > ...doesn't this hypothesis imply that DLT drives are quite broken
> > by design???
> >
> >  > My understanding is that DLT has a "warning" mark some distance from
the
> >  > end (EOT vs EOM).  The drive should attempt to write all buffered
data
> >  > after reaching the warning mark and then return EOT to the host.  If
> >  > true, then this particular issue is probably not a big deal for DLT
> >  > users.  I have no idea if other technology deals with it in similar
ways
> >  > or not.
> >
> > ...tf this understanding is true, then wouldn't the above
> > hypothesis would be false??
> >
> > Apologies for being especially ornery today.
> >
> > Has anyone read the last saves on some DLT tapes lately?
> > =:)
> >
> > Perhaps it's worth pointing out that if we second-guess
> > vendor's specs, software's functionality, and the like, then
> > there would be no time to get any real work done!
> >
> > steve
> > - - -
> > systems & network guy
> > high energy physics
> > university of wisconsin
> >
> > --
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