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RocketLink!--> Man page versions: OpenBSD

SCAN_FFS(8)             OpenBSD System Manager's Manual            SCAN_FFS(8)

     scan_ffs - find UFS/FFS partitions on a disk

     scan_ffs [-lsv] [-b begin] [-e end] device

     This is the life-saver of typo's.  If you have ever been working too
     long, and just happened to type 'disklabel -rw sd0 floppy', instead of
     'disklabel -rw fd0 floppy', you know what I am talking about.

     This little program will take a raw disk device (which you might have to
     create) that covers the whole disk, and finds all probable UFS/FFS parti-
     tions on the disk.  It has various options to make it go faster, and to
     print out information to help in the reconstruction of the disklabel.

     The following options are available:

     -l        This will make scan_ffs print out a string looking much like
               the input to disklabel.  With a little massaging, this output
               can usually be used in the disklabel edit.

     -s        This tells scan_ffs to be smart about skipping partitions (when
               it thinks it found a valid one).  By not scanning partitions
               for superblocks, the program completes a couple of orders of
               magnitude faster.  However, sometimes being smart is too good
               for it's own good, especially if your disk has had a different
               layout previously, or contains other non-UFS/FFS filesystems.

     -v        Tell scan_ffs to be verbose about what it is doing, and what it
               has found.

     -b begin  Tell scan_ffs where to begin searching for filesystems.  This
               makes it easier to skip swap partitions, or other large non-
               UFS/FFS partitions.

     -e end    Ditto for telling scan_ffs where to stop.

     device    This specifies which device scan_ffs should use to scan for
               filesystems.  Usually this device should cover the whole disk
               in question.

     The basic operation of this program is as follows:

     1.    Panic.  You usually do so anyways, so you might as well get it over
           with.  Just don't do anything stupid.  Panic away from your ma-
           chine.  Then relax, and see if the steps below won't help you out.

     2.    Try to find your old disklabel by any other means possible.  This
           includes printouts, backups, screendumps, and whatever other method
           you can think of.  The more information you have, the better your
           chances are in recovering the disklabel of the disk.

     3.    Create a disklabel on the affected disk, which covers the whole
           disk, and has at least one partition which covers the whole disk.
           As the 'c' partition usually covers the whole disk anyways, this
           sounds like a good place to start.

     4.    Run scan_ffs over this partition.  If you have any information
           about the disklabel which used to exist on the disk, keep that in
           mind while scan_ffs spews out its things.

     5.    Use disklabel(8) to reconstruct the disklabel on the affected disk,
           using all the information you gathered from scan_ffs and other

     Last but certainly not least, we wish you good luck.  The UFS/FFS
     filesystems are pretty sturdy.  I've seen them reconstructed after some
     pretty weird and awesome fumbles.  If you can't have backups, at least
     have funky tools to help you out of a jam when they happen.


     It is not perfect, and could do a lot more things with date/time informa-
     tion in the superblocks it finds, but this program has saved more than
     one butt, more than once.

OpenBSD                        January 31, 1998                              2

Source: OpenBSD 2.6 man pages. Copyright: Portions are copyrighted by BERKELEY
SOFTWARE DESIGN, INC., The Regents of the University of California, Massachusetts
Institute of Technology, Free Software Foundation, FreeBSD Inc., and others.

(Corrections, notes, and links courtesy of RocketAware.com)

[Detailed Topics]
OpenBSD sources for scan_ffs(8)

[Overview Topics]

Up to: File System Operations - Operations for entire file-systems (quotas, configuration, consistency, mount, unmount, et al)

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