ADSM-L

Recovering Damaged Files

1996-01-08 13:11:00
Subject: Recovering Damaged Files
From: "Esson, Paul" <essonpa AT XXEUPO13.HOU.XWH.BP DOT COM>
Date: Mon, 8 Jan 1996 10:11:00 PST
We recently upgraded to version 2 of ADSM for AIX and have spent the last
couple
of weeks backing up out primary tape storage pool for disaster recovery
purposes.
All was well until we hit a problem with  two particular tape volumes A00319
and A00320 which  caused the backup of the storage pool to terminate, the
messages in each case were as follows:-

ANR 9999 D asrtrv.c(471)
End reached prematurely on volume nnnnnn

ANR 1218 E
Excessive read errors on nnnnnn

When I queried the volumes there were indeed significant read errors.  I
then ran
audits on each of the volumes, fix=no, which confirmed that approximately
99%
of the files on each tape were damaged.  Further audits of the two volumes
either
side of the failing tapes, i.e. A00318 and A00321 also indicated extensive
numbers of
damaged files.

The drives in question are 3490E's, part of a C22 tape susbsystem.  There
are no
corresponding AIX hardware error reports

I next tried an image copy of one of the volumes using the AIX tcopy
utility. This
copied 80 bytes of the first record on the tape and then recognised an end
of
tape condition.  Running tcopy against each of the volumes which failed the
audit
produced exactly the same results, end of tape being reached 1 record (80
bytes) into the tape.

I am currently trying to skip past these end-of-tape markers to see if I can
copy any
valid data off the tapes, though I am unsure as to whether ADSM could read
any
such image copy? Don't know if the label will copy or is corrupt for a
start.

Has any one experienced anything remotely similar? [ I have placed a call
with
IBM UK AIX support.]

I now find myself in the situation where I cannot continue the tape pool
backup
until I resolve the issue of the damaged files on these volumes.  If I run
an audit
volume with fix=yes I suspect all database references to the files in these
volumes
will be deleted and that will be that.

Can anyone suggest an alternative plan for recovering the files ?  Any
comments
would be much appreciated.

Yours,
Paul Esson
SAIC UK
c/o BP Exploration
Aberdeen  UK
+44 (0) 1224 834418
essonpa AT xxeupo13.hou.xwh.bp DOT com
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