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Date:      Sun, 23 May 1999 01:28:11 -0500 (CDT)
From:      Chris Dillon <cdillon@wolves.k12.mo.us>
To:        "Craig A. Struble" <cstruble@vt.edu>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: Need help recovering from major mistake
Message-ID:  <Pine.BSF.4.10.9905230105310.9982-100000@mail.wolves.k12.mo.us>
In-Reply-To: <Pine.OSF.4.02.9905230127520.12492-100000@csgrad.cs.vt.edu>

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[trimmed off -hackers, this doesn't belong there]

On Sun, 23 May 1999, Craig A. Struble wrote:

> Hi, I just made a major mistake with my FreeBSD drive that I hope I can
> recover from. Not thinking too far ahead, I tried to install OS-BS on a
> dangerously dedicated FreeBSD drive. This had the unfortunate side effect
> of wiping out both the boot code and disklabel from the drive.

I made just such a blunderheaded mistake not an hour ago, though not
with OSBS, but /boot/boot0. :-) Luckily I'm back up now (or you
wouldn't be reading this).

> I'd like to
> restore them, but I don't have a printout of what the disklabel used to
> be. Therein lies the challenge.

I had a printout of my disklabels for all my disks, but couldn't find
it (figures, eh?).  After telling disklabel(8) to look in several
different places (it didn't show up on da0s1 like normal), I found it.  
I only overwrote the first 512 bytes of the disk, though.. is that all
OSBS overwrote?)

> Using my FreeBSD CD-ROMs, I've been able to go into fixit mode and mount
> the root filesystem of the drive, but I'm not sure where to go from there.
> How can I figure out what my old disklabel was? Is there some way I can
> search the raw disk for the locations of the file systems?

Since the disklabel appeared to still be there after I brain-o'd the
disk, I just went into fixit and wrote /boot/boot1 back to the disk
thinking that would be all it took to fix it.  Well, that sorta
worked, but something was still amiss because my device ordering
seemed jumbled up a bit (something got confused).  I noticed that
FDISK in sysinstall thought the disk was still "unused".  Knowing that
if I re-created that "dangerously dedicated" partition with fdisk it
would more than likely wipe out my disklabel, I went back into fixit
and copied down the disklabel by hand.  After I re-partitioned the
disk, I went into fixit again, and re-wrote the disklabel by hand.  
After doing so, the system booted normally.

If your disklabel doesn't appear to be in its normal place as far as
device nodes are concerned, try searching though all of them (may have
to MAKEDEV the right ones) for the label.  If you just can't find it,
I have no idea where to go from there.



-- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net
   FreeBSD: The fastest and most stable server OS on the planet.
   For Intel x86 and Alpha architectures (SPARC under development).
   ( http://www.freebsd.org )

   "One should admire Windows users.  It takes a great deal of
    courage to trust Windows with your data."



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