NAME    [Toc]    [Back]

     scan_ffs - find UFS/FFS partitions on a disk

SYNOPSIS    [Toc]    [Back]

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

DESCRIPTION    [Toc]    [Back]

     This is the life-saver of typos.   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 partitions
 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 options are as follows:

     -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 its
             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 nonUFS/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 machine.
   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
           sources.

     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.

SEE ALSO    [Toc]    [Back]

     disklabel(8)

BUGS    [Toc]    [Back]

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

OpenBSD     3.6                        January      31,      1998