fsck and mount disagree on whether superblocks are usable

[Martin Cracauer]

Julian H. Stacey wrote on Mon, Feb 04, 2008 at 06:27:14PM +0100: 
> Martin Cracauer wrote:
> > Julian H. Stacey wrote on Sat, Feb 02, 2008 at 08:16:30PM +0100: 
> > > Martin Cracauer wrote:
> > > > This is not an emergency but I find it odd.  Mount and fsck agree on
> > > > whether superblocks are usable.  Mount can mount readonly, but fsck
> > > > can use neither the primary superblock nor the alternatives.
> > > > 
> > > > 32 is not a file system superblock
> > > 
> > > Just in case, You know secondary block on newer FSs moved from 32 ?
> > > Ref man fsck_ufs
> > >    -b      Use the block specified immediately after the flag as the super
> > >              block for the file system.  An alternate super block is usually
> > >              located at block 32 for UFS1, and block 160 for UFS2.
> > 
> > Thanks, Julian.
> > 
> > I'm honestly don't know how to tell whether I have ufs1 or ufs2.
> 
> I didnt either, but wanted to know & just found one way:
> 
> dumpfs /dev/____ | grep -i ufs

Yupp, there you go.

The reason why it failed for me is that it was looking for the
superblocks in the wrong place. 

This works:
fsck_ffs -b 160 /dev/ad0s1a

I now need to debug why the target machine's fsck seemed to think it's
ufs1 or why else it looked at 32 when the source machine didn't.

Martin
-- 
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Martin Cracauer <cracauer at cons.org>   http://www.cons.org/cracauer/
FreeBSD - where you want to go, today.      http://www.freebsd.org/