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Date:      Wed, 4 Sep 1996 11:35:11 -0700
From:      Sean Eric Fagan <sef@Kithrup.COM>
To:        hackers@freebsd.org
Subject:   reported disk corruption
Message-ID:  <199609041835.LAA20615@kithrup.com>

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My friend Torbjorn reported this to questions, but didn't get a response.
Since he has given up on freebsd as a result of that, but this is still
something that should probably be reported, I'm forwarding it to hackers...

From: Torbjorn Granlund <tege@matematik.su.se>
Subject: Desperation time

Just two weeks ago, I swapped disks and got a new Ultra SCSI controller.
The new disk is a 4.4GB Fujitsu 2954SAU, and the controller is an Adaptec
2940UW.  At the same time, I upgraded from FreeBSD 2.1 to 2.1.5.

During installation, the FreeBSD installtion program complained that the
disk label (of the pristine SCSI disk) was bad, and gave me the option to
procdeed or to modify it.  I chose to modify it, giving what I though were
the correct parameters.  From the output of `disklabel sd0' one might
conclude that the disklabel is wrong:

  quiet> disklabel -r sd0
  # /dev/rsd0c:
  type: SCSI
  disk: sd1s1
  label: 
  flags:
  bytes/sector: 512
  sectors/track: 1
  tracks/cylinder: 1
  sectors/cylinder: 1
  cylinders: 1
  sectors/unit: 8498506
  rpm: 3600
  interleave: 1
  trackskew: 0
  cylinderskew: 0
  headswitch: 0           # milliseconds
  track-to-track seek: 0  # milliseconds
  drivedata: 0 

  8 partitions:
  #        size   offset    fstype   [fsize bsize bps/cpg]
    a:   131072        0    4.2BSD        0     0     0   # (Cyl.    0 - 131071)
    b:   282624   131072      swap                        # (Cyl. 131072 - 413695)
    c:  8498506        0    unused        0     0         # (Cyl.    0 - 8498505)
    e:   131072   413696    4.2BSD        0     0     0   # (Cyl. 413696 - 544767)
    f:  6348800   544768    4.2BSD        0     0     0   # (Cyl. 544768 - 6893567)
    g:  1604938  6893568    4.2BSD        0     0     0   # (Cyl. 6893568 - 8498505)

Note the wild cylinder numbers!

Today, my 3.1 GB /usr file system started to act weird.  When doing `ls -l'
in a directory, I got "Bad file descriptor" for one of the directories.
When running fsck, it said "/foo/bar/foobar unallocated, delete?".  fsck
complained like that about a large number of files.  I also got a large
number of unref files and files with incorrect counts.

A curious facts is that all the problematic files had inode numbers around
253600 or 491900.

Does this information give any hint on what might be wrong?  Is the bogus
disklabel the culprit?  Isn't the geometry simply used for scheduling of
disk accesses?  The total number of sectors and thereby the disk size seems
to be correct.

I used to keep my partitions below 2GB, to avoid potential problems with
integer overflow in the kernel.  Now I decided to try with a larger file
system.  Could the file system size be the culprit?

I am desperate to get my system going again.  Now, I don't dare to modify
any files, and that makes it somewhat hard to do useful work..  Is there a
FreeBSD mailing list for asking about this?

(Fortunately, I have a recent backup.)

Torbjorn




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