Red light after power failure

My device doesn’t mount disks after a power failure. Attached one of the disks to a Linux box and tried to mount it without success. It seems like the superblocks are missing. Any help is greatly appreciated. I’ve removed one of the disks as a backup. Currently disk A is in the device.

MyBookLiveDuo:~# cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md3 : active raid1 sda4[0]
1948997496 blocks super 1.2 [1/1] [U]

md2 : active raid1 sda3[1]
500724 blocks super 1.0 [2/1] [_U]

md1 : active raid1 sda2[2] sda1[0]
1999808 blocks [4/2] [U\_U\_]

MyBookLiveDuo:~# mount /dev/md3 /mnt/
mount: you must specify the filesystem type

MyBookLiveDuo:~# mount -t ext3 /dev/md3 /mnt/
mount: wrong fs type, bad option, bad superblock on /dev/md3,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

MyBookLiveDuo:~# dumpe2fs /dev/md3
dumpe2fs 1.41.12 (17-May-2010)
dumpe2fs: Bad magic number in super-block while trying to open /dev/md3
Couldn’t find valid filesystem superblock.

Put it back on the linux box and delete all the partition data. 

Then put it back in the Duo.  

I would assume the Duo will then be able to rebuild.

Thanks for the reply. Wouldn’t that delete the data in the process?

Have you tried booting your DUO with only the single drive installed?   I have, and it does work.

As long as one remaining drive is still OK, then your content should be fine on that disk (since you’re configured for RAID1.)

Or are you saying that it won’t boot even if EITHER disk is in?

It does boot. The device is running with a single disk right now. The problem is, it doesn’t mount the data partition (md3) And I can’t access my data.

And the same happens if you try to single-disk-boot the other disk as well?

Yes, that’s right.

Hmm. Well, I’m not sure if this makes a difference or not, but on my system, /dev/md3 is an ext4 system, not ext3:

BIGNAS3:~# cat /etc/mtab | grep ext
/dev/md0 / ext3 rw,noatime,nodiratime,barrier=1 0 0
/dev/md3 /DataVolume ext4 rw,noatime,nodiratime 0 0

Assuming md3 is the data partition and sda4 is a member, can you run these on your system?

dumpe2fs /dev/md3 |grep superblock

dumpe2fs /dev/sda4 |grep superblock

BIGNAS3:~# dumpe2fs /dev/md3 |grep superblock ; dumpe2fs /dev/sda4 |grep superblock
dumpe2fs 1.41.12 (17-May-2010)
  Primary superblock at 0, Group descriptors at 1-1
  Backup superblock at 65528, Group descriptors at 65529-65529
  Backup superblock at 196584, Group descriptors at 196585-196585
  Backup superblock at 327640, Group descriptors at 327641-327641
  Backup superblock at 458696, Group descriptors at 458697-458697
  Backup superblock at 589752, Group descriptors at 589753-589753
  Backup superblock at 1638200, Group descriptors at 1638201-1638201
  Backup superblock at 1769256, Group descriptors at 1769257-1769257
  Backup superblock at 3210872, Group descriptors at 3210873-3210873
  Backup superblock at 5307768, Group descriptors at 5307769-5307769
  Backup superblock at 8191000, Group descriptors at 8191001-8191001
  Backup superblock at 15923304, Group descriptors at 15923305-15923305
  Backup superblock at 22476104, Group descriptors at 22476105-22476105
  Backup superblock at 40955000, Group descriptors at 40955001-40955001
dumpe2fs 1.41.12 (17-May-2010)
  Primary superblock at 0, Group descriptors at 1-1
  Backup superblock at 65528, Group descriptors at 65529-65529
  Backup superblock at 196584, Group descriptors at 196585-196585
  Backup superblock at 327640, Group descriptors at 327641-327641
  Backup superblock at 458696, Group descriptors at 458697-458697
  Backup superblock at 589752, Group descriptors at 589753-589753
  Backup superblock at 1638200, Group descriptors at 1638201-1638201
  Backup superblock at 1769256, Group descriptors at 1769257-1769257
  Backup superblock at 3210872, Group descriptors at 3210873-3210873
  Backup superblock at 5307768, Group descriptors at 5307769-5307769
  Backup superblock at 8191000, Group descriptors at 8191001-8191001
  Backup superblock at 15923304, Group descriptors at 15923305-15923305
  Backup superblock at 22476104, Group descriptors at 22476105-22476105
  Backup superblock at 40955000, Group descriptors at 40955001-40955001

TonyPh12345, that information helped me save my data. Thank you, I really appreciate it.

For anyone who has the same problem, here is what I did:

Attached one of the disks to a PC. Normally dumpe2fs should show the superblock locations but for some reason it didn’t work. Using Tony’s dumpe2fs output, I’ve used 65528 with e2fsck:

e2fsck -b 65528 /dev/md0

It askes lots of questions, I’ve said yes to all.

After that, it was ready to mount. But it didn’t mount on a PC, you need a Power PC to mount it. So I’ve attached it to My Book again and ran:

mdadm --stop /dev/md3

mount -t ext4 /dev/sda4 /mnt/

All the data was under lost+found

I hope this helps someone else.