recovery after power outage

Jerry McAllister jerrymc at
Mon Feb 12 15:27:19 UTC 2007

On Fri, Feb 09, 2007 at 04:48:44PM -0500, Marty Landman wrote:

> On 2/9/07, Jerry McAllister <jerrymc at> wrote:
> >
> >On Fri, Feb 09, 2007 at 12:06:20PM -0500, Marty Landman wrote:
> >
> >>> Information from DOS bootblock is:
> >>> The data for partition 1 is:
> >>> sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
> >>>    start 63, size 490223412 (239366 Meg), flag 80 (active)
> >>>        beg: cyl 0/ head 1/ sector 1;
> >>>        end: cyl 1023/ head 254/ sector 63
> >Hmmm.   That looks pretty normal to me.
> Cool, hoping that is an omen of good things to come.
> >What does bsd label show for it?
> >
> >> As root, do:    bsdlabel ad1s1
> %sudo bsdlabel ad1s1
> # /dev/ad1s1:
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
>  c: 490223412        0    unused        0     0         # "raw" part, don't
> edit
> %
> So where do I stand?

Hmmm.   Well, that looks like a slice that has not been partitioned - 
which is essentially what you have been telling us it is.  That is
not 'dangerously dedicated'.  It is instead an incompletely partitioned
and build slice.

It has type 'unused' which is what the 'c' partition should be and
as such, should not be used.   

I am wondering what would happen it you tried to mount /dev/ad1s1
without the 'c'.   It shouldn't hurt anything to try that.

I don't know if fsck might work on that.  You might try it (as /dev/ad1s1)  
with a '-d' flag to see what it might try without actually writing anything 
to the drive and potentially wrecking something.   Make sure it is not
mounted before trying the fsck.

Did you build a filesystem on this slice with newfs?   I don't remember
if you said.  If so, you can try looking for superblocks.   Again, I 
might try using just /dev/ad1s1 without the 'c' to check things.

If you have space for it somewhere, you could also try to dd some of
the drive.    
  dd if=/dev/ad1s1 of=some_file_on_another_disk bs=512 count=10000
That would copy 5 MB    Then you could play with that data in hex
or with some debugger (hexdump??) that lets  you muck with it a byte 
at a time in hex, ASCII, octal, etc and see what you can find. 

You would have to look at it with filesystem documentation in hand
to make any sense of it.


> Marty
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