How to recover data? - Formatted, Fdisk'd, and disklabeled ad1, now ad0 with FreeBSD is messed up

Mark Kane mark at
Mon Aug 8 05:00:47 GMT 2005

Gary W. Swearingen wrote:
> Hmmm.  I didn't know that "s1" could be mounted since the
> filesytem doesn't start until at least 16 sectors after the start
> of "s1".  But "bsdlabel" show that my "a" starts at 0 offset from
> the start of my "s3", so "s1" and "s1a" must be pretty-much the
> same thing as far as mounting is concerned.
> I'd try mounting /dev/ad0s1a anyway; your non-standard way might
> confuse it.
> BTW, I'd always mount ad0 stuff with -r flag until I got my data
> off it.  I'd probably start by disconnecting it's IDE cable at
> least until I had FreeBSD running off your 60 GB drive.  And
> then hook it up and try to make it mountable read only.

Mounting /dev/ad0s1a showed what was my root partition before. I tried 
mounting ad0s1b, and it gave "Incorrect Super Block". I went on to guess 
ad0s1f, mounted it, and it was /usr. Appears like /usr/home/myuser/ 
exists and my files are there.

> (A supposedly better alternative to writing all zeros is writing random
> numbers, which is pretty-much what your NTFS disk would have looked
> like to another OS like FreeBSD.  (Zeros are not as good because with
> the right tools (very hard to do), your old data can be read in left-
> over magnetism, but that's MUCH harder if random data has been used.)
> That quote is the only thing you've said in your msg that looks
> suspicious to me.  Could the Maxtor stuff have done something to your
> first disk's MBR?  Support people always have to point to the other
> guy, right?

Yeah, I've heard that random numbers is better, however I wasn't trying 
cover any tracks, just start clean.

The Maxtor software could not have done something to ad0 because:

1) I had the FreeBSD drive unplugged when I did the format.
2) I did the format before partitioning it, and it booted to FreeBSD 
fine to partition it.

> When you get FreeBSD running on a 60 GB, or if you think the Fixit CD
> is working OK, run "fdisk ad0" and "bsdlabel ad0s1".  I still didn't
> understand if you had more than a ad0s1a before your problem, so I'm
> not sure what should look normal from those commands. But you can
> probably tell if it looks right.

My ultimate goal is to get this install of FreeBSD on ad0 to boot again, 
and make sure ad1 is ready in UFS for the data to be dumped back on to 
it. Then dump the data back on, see if my DMA problem from before goes 
away, and then proceed to get the other drives copied, formatted, and 

Then when all that is complete and all my drives are in UFS, I plan to 
reinstall FreeBSD on the 160GB drive, since this install was pretty much 
a test to determine if I wanted to run the amd64 or i386 version of 
FreeBSD. (Was not sure if I could deal with no Java/linux-firefox/flash 
plugin, but I think I can)

I'm not sure given the info that I have what the proper way to get 
FreeBSD back up and running again, and to make sure ad1 is ready is.

I replied to a reply on the list a few minutes ago saying that if I 
mount /dev/ad1s1d, it shows the full 55G size and 51G avail that is 
supposed to be the ad1 60GB drive. I'm not sure why that's "d" though.



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