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scan_ffs

    1: .\"	$OpenBSD: scan_ffs.8,v 1.11 2000/11/09 17:53:07 aaron Exp $
    2: .\"
    3: .\" Copyright (c) 1997 Niklas Hallqvist, Tobias Weingartner
    4: .\" Copyright (c) 2002, 2003 Robert Watson, Michael Ranner
    5: .\" All rights reserved.
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   27: .\" .TH scan_ffs 8
   28: .Dd January 31, 1998
   29: .Dt SCAN_FFS 8
   30: .Os
   31: .Sh NAME
   32: .Nm scan_ffs
   33: .Nd find UFS/FFS partitions on a disk
   34: .Sh SYNOPSIS
   35: .Nm scan_ffs
   36: .Op Fl lsv
   37: .Op Fl b Ar begin
   38: .Op Fl e Ar end
   39: .Ar device
   40: .Sh DESCRIPTION
   41: This is the life-saver of typos.
   42: If you have ever been working too long,
   43: and just happened to type 'disklabel -rw da0 floppy', instead of 'disklabel
   44: -rw fd0 floppy', you know what I am talking about.
   45: .Pp
   46: This little program will take a raw disk device (which you might have to
   47: create) that covers the whole disk, and finds all probable UFS/FFS partitions
   48: on the disk.
   49: It has various options to make it go faster, and to print out
   50: information to help in the reconstruction of the disklabel.
   51: .Pp
   52: The options are as follows:
   53: .Bl -tag -width Ds
   54: .It Fl l
   55: This will make
   56: .Nm
   57: print out a string looking much like the input to disklabel.
   58: With a little massaging, this output can usually be used in the disklabel edit.
   59: .Pp
   60: .It Fl s
   61: This tells
   62: .Nm
   63: to be smart about skipping partitions (when it thinks it found a valid one).
   64: By not scanning partitions for superblocks, the program completes a couple of
   65: orders of magnitude faster.
   66: However, sometimes being smart is too good for
   67: its own good,
   68: especially if your disk has had a different layout previously, or contains
   69: other non-UFS/FFS filesystems.
   70: .Pp
   71: .It Fl v
   72: Tell
   73: .Nm
   74: to be verbose about what it is doing, and what it has found.
   75: .Pp
   76: .It Fl b Ar begin
   77: Tell
   78: .Nm
   79: where to begin searching for filesystems.
   80: This makes it easier to skip swap
   81: partitions, or other large non-UFS/FFS partitions.
   82: .Pp
   83: .It Fl e Ar end
   84: Ditto for telling
   85: .Nm
   86: where to stop.
   87: .Pp
   88: .It Ar device
   89: This specifies which device
   90: .Nm
   91: should use to scan for filesystems.
   92: Usually this device should cover the whole disk in question.
   93: .Pp
   94: .El
   95: .Pp
   96: The basic operation of this program is as follows:
   97: .Bl -enum -width "1111"
   98: .It
   99: Panic.
  100: You usually do so anyways, so you might as well get it over with.
  101: Just don't do anything stupid.
  102: Panic away from your machine.
  103: Then relax, and see if the steps below won't help you out.
  104: .It
  105: Try to find your old disklabel by any other means possible.
  106: This includes
  107: printouts, backups, screendumps, and whatever other method you can think of.
  108: The more information you have, the better your chances are in recovering the
  109: disklabel of the disk.
  110: .Pp
  111: .It
  112: Create a disklabel on the affected disk, which covers the whole disk, and has
  113: at least one partition which covers the whole disk.
  114: As the
  115: .Dq c
  116: partition
  117: usually covers the whole disk anyways, this sounds like a good place to start.
  118: .Pp
  119: .It
  120: Run
  121: .Nm
  122: over this partition.
  123: If you have any information about the disklabel
  124: which used to exist on the disk, keep that in mind while
  125: .Nm
  126: spews out its things.
  127: .Pp
  128: .It
  129: Use
  130: .Xr disklabel 8
  131: to reconstruct the disklabel on the affected disk, using
  132: all the information you gathered from
  133: .Nm
  134: and other sources.
  135: .Pp
  136: .El
  137: .Pp
  138: Last but certainly not least, we wish you good luck.
  139: The UFS/FFS filesystems are pretty sturdy.
  140: I've seen them reconstructed after some pretty weird and
  141: awesome fumbles.
  142: If you can't have backups, at least have funky tools to help
  143: you out of a jam when they happen.
  144: .Sh SEE ALSO
  145: .Xr disklabel 8
  146: .Sh HISTORY
  147: The
  148: .Nm
  149: utility first appeared in
  150: OpenBSD 2.3 and was ported to
  151: .Fx
  152: by Robert Watson. UFS2 Support was added by Michael Ranner.
  153: .Sh BUGS
  154: It is not perfect, and could do a lot more things with date/time information
  155: in the superblocks it finds, but this program has saved more than one butt,
  156: more than once.