Jay,

thanks for all this info.  I am able to run these dd commands successfully.  So 
I'm beginning to think that amanda is the source of the problem.  However, 
before I go any further, I'm extracting the data from the tapeimages to ensure 
that tar doesn't crash.

-Rob

> -----Original Message-----
> From: Jay Fenlason [mailto:fenlason AT redhat DOT com]
> Sent: Wednesday, April 07, 2004 5:20 PM
> To: Dege, Robert C.
> Subject: Re: AIT-2
> 
> 
> On Wed, Apr 07, 2004 at 01:23:53PM -0700, Dege, Robert C. wrote:
> > 
> >  
> > > Can you take one of your backup tapes and access the files on it
> > > reliably with dd?  If you can't, it's likely to be a 
> hardware/os/etc
> > > problem.  If you can, it may be an Amanda problem.
> > > 
> > > Is there any chane of bad termination on your SCSI chain?
> > 
> > What would the dd command line be?
> 
> Start with the tape rewound.
> cd to a directory with a lot of space.  (Up to 50Gb if you want to
> read your entire AIT-2 tape.)
> 
> dd < /dev/nst0 > tapeimage.1 bs=32k
> dd < /dev/nst0 > tapeimage.2 bs=32k
> dd < /dev/nst0 > tapeimage.3 bs=32k
> dd < /dev/nst0 > tapeimage.4 bs=32k
> dd < /dev/nst0 > tapeimage.5 bs=32k
> dd < /dev/nst0 > tapeimage.6 bs=32k
> ...
> (Repeat the dd command until it creates an empty file.)
> 
> The first tapeimage file will be the Amanda tape label.  The last file
> with data in it will be the Amanda tape end marker.  The other files
> will be the backups.  If dd read all the backups and the end marker
> successfully, any remaining problem is likely to be Amanda's.
> 
> Each of the backups is going to be a (possibly compressed) dump output
> file or a (possibly compressed) tar file.  Either way, there's a 32k
> header that you need to skip over to get at the actual data.  If
> they're tar files, you should be able to read them with
> 
> dd < tapeimage.n bs=32k skip=1 | gtar tvf -
> 
> If they're compressed tar files, you'll need
> 
> dd < tapeimage.n bs=32k skip=1 | gunzip | gtar tvf -
> 
> If they're dump files, I don't know how to read them.  Check the
> restore man page.
> 
> > Right now, I'm running a tar command directly to a standard AIT-2
> > tape.  I want to see if the problem is with tar, or with 
> amanda using
> > tar.  I'm tarring files to the tape, and then will try to 
> extract the
> > files.  I'm also using the same file chunk that failed on amanda to
> > eliminate any additional variables in my test.
> 
> > I don't think SCSI termination is the problem since I can use the
> > tape changer without any problems, and backups occur 
> without error on
> > a nightly basis.  I'll double-check tough.
> 
> If it's a hardware or OS problem, your tar test should find it.
> 
>                       -- JF
>