Trying to recover data from FreeBSD 4.11 system

Jerry McAllister jerrymc at
Thu Feb 14 17:08:02 UTC 2008

On Thu, Feb 14, 2008 at 01:08:35AM -0500, Joe Demeny wrote:

> I have an old Cyrix computer which doesn't post any more.
> It had 3 hard drives. The boot drive had the / partition as well as /usr 
> and /var, and the other 2 drives were configured with Vinum RAID 1 for /home.
> I hooked up what used to be the boot drive in a new system and it showed what 
> looked like some hex numbers and then the error message "BTX halted".
> So, I installed this drive as the second hard drive in a FreeBSD 6.2 system 
> and I tried to mount it, but I got "incorrect super block".
> Looks like I have /dev/ad1, /dev/ad1s1, /dev/ad1s1c, and /dev/ad1s1e.

That sounds very unlikely because /dev/ad1, /dev/ad1s1 and /dev/ad1s1c
overlap each other in naming/identity.   

My first question would be which FreeBSD version was used to create
that disk?   If it is not too old or later, then there should 
be no problem.

Use fdisk to find out how it sees the drive.  Do     fdisk ad1
and check out what it says.   Especially look to see what slices
that fdisk thinks it has.   Maybe there is only an  s1  active
with anything in it.  That would be easiest and very common.

Then use bsdlabel to look at what partitions are defined in any 
of the slices.     do baslabel ad1s1  (for slice 1,  ad1d2  as well
if there is a slice 2 being used, etc)
>From root, do  bsdlabel ad1d1     and see what partitions are defines.
Remember that partition 'c' is not a real partition, but a label to
define the whole slice to the system (it will have a type of 'unused')
and that in most cases partition 'b' is used for swap (and will have
a type of 'swap'), though it does not have to be swap.
The other partitions; a, d, e, f, g, h, could be real partitions with
something on them.   Almost certainly the 'a' partition will be root
on a bootable slice.

Do an fsck on each real partition.  'fsck /dev/ad1s1a'  etc

Then create a mount point and try to mount it.

  mkdir /olda            (the name is arbitrary, just needs to be unigue)

  mount /dev/ad1s1a /olda

If this all doesn't work, then problems are more serious and you may
not be able to recover the data.   Anyway, you will need to try more
extreme measures.


> Is there a way to mount these filesystems?
> -- 
> Joe Demeny
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