Corrupt GPT header on disk from twa array - fixable?

[Alban Hertroys]

Hello list,

I just replaced my home server and moved the disks from the old one over to the new one. In the old server, 4 of the disks were connected to a twa (3Ware 9550) controller, which of course has it's own way of marking units/volumes on those disks.

Before you start yelling at me, yes, of course I made backups ;) [*]

The thing is, I have these disks in the new server and I found that I (to my surprise) I can actually mount them! But, I'm missing a large part and I am wondering if there's some method to access those last partitions too.

Here's what gpart show says about the problematic disk:

# gpart show /dev/ada4
=>      34  41942972  ada4  GPT  (931G) [CORRUPT]
        34       128     1  freebsd-boot  (64k)
       162   1048448     2  freebsd-ufs  (512M)
   1048610   6291456     3  freebsd-swap  (3.0G)
   7340066   1048576     4  freebsd-ufs  (512M)
   8388642   2097152     5  freebsd-ufs  (1.0G)
  10485794  31457211     6  freebsd-ufs  (15G)
  41943005         1        - free -  (512B)

As you can see, most (about 910GB) of the disk is missing! This disk was one half of a mirror on the twa controller, which had those disks split in two again (I don't recall how, perhaps 2 different BSD slices?)
I already looked if that part may perhaps have ended up as a different device. On the old server, fstab was this:

# cat /tmp/solfertje/etc/fstab
# Device        Mountpoint      FStype  Options Dump    Pass#

# These are the partitions listed above in gpart
/dev/da0p2      /               ufs     rw      1       1
/dev/da0p3      none            swap    sw      0       0
/dev/da0p4      /var            ufs     rw      2       2
/dev/da0p5      /tmp            ufs     rw      2       2
/dev/da0p6      /usr            ufs     rw      2       2

# These are missing
/dev/da1p1      /home           ufs     rw      2       2
/dev/da1p2      /media          ufs     rw      2       2

# These are on a different disk (ada2)
/dev/da2p1      /media2         ufs     rw      2       2


I don't _really_ need to get to those partitions, but it would be a comfortable thought if it were possible somehow.


[*] The reason I was trying to access those disks anyway is that I thought I forgot to backup my database tables, but it turns out I had just misplaced that backup and it has been restored now.

Alban Hertroys
--
If you can't see the forest for the trees,
cut the trees and you'll find there is no forest.