As it was predicted EOD mark has been written on the volume during
labeling. AUDIT VOL reported all files as irretrievable.




"Daniel G. Crouse" <DGCrouse AT ix.netcom DOT com> on 23/07/98 14:04:49

Please respond to DGCrouse AT ix.netcom DOT com

To:   adsm-l AT vm.marist DOT edu
cc:   rbs AT bu DOT edu, rcbell AT US.IBM DOT COM, Anton Gubarkov/SONY CIS AO
Subject:  RE: Destroyed volume label on DDS2 volume




Craig and others,
Relabeling a tape  is an old technique that could be used to salvage data
on
DFHSM tapes after they had been inadvertently relabeled.  I am pretty
confident that I used this same technique with earlier versions of ADSM to
successfully salvage data on a  tape (on an MVS server).  It has been a
while since then, but  I was not aware that anything had changed.  It would
be interesting to know if different operating systems and/or tape drives
handle tape marks differently. The utility may make a tape mark and ADSM
may
be able to read past it since it "knows" where its data is on the tape.  If
what you have said is accurate, the damage has already been done and
relabeling the tape will not result in any additional data loss, so it
still
may be worth a try. Thank you for keeping me "honest".
DanC
=============================================
Daniel G. Crouse
IBM Certified Specialist - ADSM
Mainstar Software Corporation
Storage and Recovery Solutions
  URL:  www.mainstar.com
Email:  Dan.Crouse AT mainstar DOT com
Vmail:  800-233-6838
Voice:  770-682-7739
   Fax:  770-682-7739
=============================================
Date:    Wed, 22 Jul 1998 11:53:34 -0400
From:    Craig Bell <rcbell AT US.IBM DOT COM>
Subject: Re: Destroyed volume label on DDS2 volume
> One technique that you may want to try is to label the volume again w=
ith the
>same volume name using the dsmlabel utility.  Since ADSM only writes t=
he
>label and does not format the tape volume, any data that is still on t=
he
>tape should become available.  I would suggest that you run an AUDIT V=
OLUME
>against the volume to clean up any data that may have been overwritten=
 in
>the original mishap.  On you other issue, you can update the original =
volume
>to READONLY status, which will still allow you read the data on the ta=
pe,
>but will also force migration to use a new tape.  Please let me know i=
f this
>approach was successful.
This technique would only work on R/W Optical devices.  On ALL Tapes, w=
hen you
write data, the drive applies an EndOfData mark following the last writ=
e, and
all data
following that is Gone.  So this data was lost when the operator caused=
 the
overwrite
at the beginning.  Re-labelling in this case would be superfluous, and =
by
itself would
destroy the whole tape if an otherwise good tape were to be relabelled.=

Craig