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corrupt data tape

This could be user error - he might have backed up a corrupt file. As Jeff noted, if the tape was bad, it should have shoe-shined and the drive would have reported the error.

Many tape drives have diagnostics built in.

Although not relevant here, accidentally writing an EOT mark is not easy to recover from.

From: Jeff Liebermann <jeffl@comix.santa-cruz.ca.us>
Newsgroups: comp.unix.sco.misc
Subject: Re: Big Trouble with tape & cpio
Date: Wed, 24 May 2000 01:01:16 -0700
Message-ID: <m72nisk77d3oj09b6h222itv19rjuamcko@4ax.com> 
References: <MPG.13912253b932760b989682@news.skyweb.net> 

On Sat, 20 May 2000 23:30:14 -0400, Fred Goldberg <fred@JUNKackcomm.com>
wrote:

>OS = SCO 5.0.5 Enterprise
>Tape Drive = Wangtek 1/4" tape (DC600 cartridge)

Model of drive and controller?  One specific Wangtek QIC-150 drive (I have
to dig though my files in the office to get the exact model number and
firmware version) had a nasty habit of running over the track sync burst
markers at each end of the tape and getting lost.  The effect is that it
would stop very near the end of the tape and eventually belch "tape read
error" or something similar.  It would write perfectly and read horribly.  I
got lucky and guessed that if I could keep it from overshooting, it would
not screw up.  So, I dragged my finger on the capstain and drive belt
sufficiently to stop the tape.

>Backup Method = cpio

Could I trouble you for the exact command you used to create the backup?

>There is one corrupt file on all of my backup tapes.

By any chance, is this "file" at the end of a tape track?

>I've tried using the "k" option to pass this point but the tape stops and 
>does nothing until I hit the break key.

No way.  If there were any kind of data read error, the tape would
shoe-shine for a while, and eventual belch "tape read error".  Since it
apparently just stopped, it thinks it found an EOF or EOT marker.  If you're
using the non-rewind device name, this is normal.

>I also tried the "k" option with 
>and without the "f <file name>" option to skip this file but had the same 
>results.

The "k" option will ignore mutilated data read from the tape, but will not
ignore media and drive failures.

>I'm in deep dodo. Any suggestions? Thanks.

Try this:
        tape -s -a 2 rfm 
This should skip forward to the 2nd file mark on the tape.  Then issue your
unspecified cpio read command.

Incidentally, OnTrack is expensive, but worth it.  They saved two of my
customers from disaster at the cost of about $550/ea for a miraculous drive
trashout recovery.


-- 
Jeff Liebermann   jeffl@comix.santa-cruz.ca.us
150 Felker St #D  Santa Cruz CA  95060
831-421-6491 pager   831-429-1240 fax
http://www.cruzio.com/~jeffl/sco/   SCO stuff

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