[CentOS] HowTo Recover Lost Data from LVM RAID1 ?

Fri Jan 18 20:47:18 UTC 2008
Alain Reguera Delgado <alain.reguera at gmail.com>

Guys,

The other day while working on my old workstation it got frozen and
after reboot I lost almost all data unexpectedly.

I have a RAID1 configuration with LVM. 2 IDE HDDs.

md0 .. store /boot (100MB)
--------------------------
/dev/hda2
/dev/hdd1

md1 .. store / (26GB)
--------------------------
/dev/hda3
/dev/hdd2

The only info that still rest in was that, that I restore after the
fresh install. It seems that the disk were with problems and weren't
syncing :(. I confessed, I didn't check that at first time but after I
lost the data and check /var/log/messages I saw that.

>From /var/log/messages
...
Jan 17 12:22:15 zion kernel: md: raid1 personality registered for level 1
Jan 17 12:22:15 zion kernel: device-mapper: ioctl: 4.11.0-ioctl
(2006-09-14) initialised: dm-devel at redhat.com
Jan 17 12:22:15 zion kernel: md: Autodetecting RAID arrays.
Jan 17 12:22:15 zion kernel: md: invalid raid superblock magic on hda3
Jan 17 12:22:15 zion kernel: md: hda3 has invalid sb, not importing!
Jan 17 12:22:15 zion kernel: md: autorun ...
Jan 17 12:22:15 zion kernel: md: considering hdd2 ...
Jan 17 12:22:15 zion kernel: md:  adding hdd2 ...
Jan 17 12:22:15 zion kernel: md: hdd1 has different UUID to hdd2
Jan 17 12:22:15 zion kernel: md: hda2 has different UUID to hdd2
Jan 17 12:22:15 zion kernel: md: created md1
Jan 17 12:22:15 zion kernel: md: bind<hdd2>
Jan 17 12:22:15 zion kernel: md: running: <hdd2>
Jan 17 12:22:15 zion mcstransd: mcstransd starting
Jan 17 12:22:15 zion kernel: raid1: raid set md1 active with 1 out of 2 mirrors
Jan 17 12:22:15 zion kernel: md: considering hdd1 ...
Jan 17 12:22:15 zion kernel: md:  adding hdd1 ...
Jan 17 12:22:15 zion kernel: md:  adding hda2 ...
Jan 17 12:22:15 zion kernel: md: created md0
Jan 17 12:22:15 zion kernel: md: bind<hda2>
Jan 17 12:22:15 zion kernel: md: bind<hdd1>
Jan 17 12:22:15 zion kernel: md: running: <hdd1><hda2>
Jan 17 12:22:15 zion kernel: md: kicking non-fresh hdd1 from array!
Jan 17 12:22:15 zion kernel: md: unbind<hdd1>
Jan 17 12:22:15 zion kernel: md: export_rdev(hdd1)
Jan 17 12:22:15 zion kernel: raid1: raid set md0 active with 1 out of 2 mirrors
Jan 17 12:22:15 zion kernel: md: ... autorun DONE.
...

This computer is old, Celeron 800MHz, 256MB of RAM and IDE disk too.

I know that I have to suffer the consequences but if you know some way
to recover some data, I'll appreciate it very much.

These days I have been reading about: mdamd, and some way to recover
but no success.

I tried to boot from rescue mode with CentOS 5 first CD and do an fsck
to /dev/hda3 and /dev/hdd2. After this something about superblock was
told to me and that use the command e2fsck -b 8123 <device> (I don't
remember the number exactly) but no success either.

Do you have some idea what we can do to recover the data on m1 ?

Thanks guys,

Cheers,
al.