SUMMARY: recovering data from corrupt SunOS bar format floppies

From: Sean Walmsley <sean.p.walmsley_at_Hydro.ON.CA>
Date: Wed Jan 30 2002 - 21:13:47 EST
I only received one reply from Bernhard Sadlowski
<sadlowsk@Mathematik.Uni-Bielefeld.DE> who suggested

  - GNU's dd command with the conv=noerror option
  - the afio command from
The dd replaces bad reads with zeros; this avoids a
read error but cpio sees these zeros as the end of the
archive so no joy.

The afio command does not seem to support the -H bar
option so it didn't help either.

Fortunately, the user in question had an archive from a
few months earlier that I was able to recover the most important
files from using cpio. Any files not on the earlier archive
he'll either have to do without or poke through the dd'd
archives using vi himself :-)

My orignal post:

I've been asked to recover files from a 10+ year old set of nine 1.44Mb
floppies written with the SunOS bar command. The archive set contains
several hundred files compressed with the compress command.

Our systems are all Solaris 2.6 or 8 which doesn't appear to have the
bar command so I did the following:

cpio -i -d -H bar -I /dev/rdiskette0

This starts dumping the data but stops after about 220kb apparently
because the first disk has been corrupted in some way. I confirmed
this by using dd to read all of the floppies in single files as

dd bs=18k if=/dev/rdiskette of=./vol[1..9]

Floppies 2 through 9 produce files of the expected size but floppy 1
returns a read error after about 220kb.

I've tried using the cpio command above to read data from the 8
undamaged floppies, but it complains that:

error: This is not volume 1.  This is volume 2.  Please insert volume 1.

I've also tried the -k option of cpio (skip over corrupted file
headers) with no success.

Is there a practical way to recover the files from the disks that
aren't damaged? It seems unfortunate that a problem with the first
disk would prevent recovery of the other 90% of the data, especially
as the first disk does not appear to contain any special directory
information for the archive. Does someone have a tweaked version
of bar that can simply skip over the damaged portions of an archive.

If worst comes to worst I suppose I may be able to vi the vol[1..9]
files created with dd, separate the headers from the file portions and
then manually run uncompress on each separated portion. I haven't tried
this yet because the fact that the files were compressed before archiving
makes them very difficult to vi.

I've looked in the FAQ, tried the sun managers search site at and done a search
on Google with no results.

Any help would be greatly appreciated.
Sean Walmsley, Nuclear Analysis Dept., Ontario Power Generation      416-592-4608 (V)  416-592-5528 (F)
700 University Ave (H11 G26), Toronto, Ontario, M5G 1X6, CANADA
sunmanagers mailing list
Received on Fri Feb 1 15:49:41 2002

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