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#1 2010-04-09 13:04:21

jesoliveira
Member
Registered: 2010-04-08
Posts: 2

"superblock could not be read" + lvm2

Hello guys,

after a power failure my system stop working, the boot procedure stops with the following msg:

:: Checking Filesystems
/dev/VolGroup00/LogVol02:
The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternative superblock: e2fsck -b 8193 <device>

I commented the fstab line '/dev/VolGroup00/LogVol02  /home ext3 defaults   1 2', now I can loging and try to recover my data. In order to solve the problem I was following this thread http://bbs.archlinux.org/viewtopic.php?id=35412

I did the following steps:
1) Identify superblock backup #mkfs.ext3 -n /dev/sdb1

2) Run the e2fsck using an alternative superblock #e2fsck -y -b 98304 -B 4096 /dev/sdb1

/dev/sdb1 was not cleanly unmounted, check forced.
Resize inode not valid.  Recreate? yes

Pass 1: Checking inodes, blocks, and sizes
Programming error?  block #768 claimed for no reason in process_bad_block.
Programming error?  block #768 claimed for no reason in process_bad_block.
Root inode is not a directory.  Clear? yes

Inode 1476116 has illegal block(s).  Clear? yes

Illegal block #464945 (1270814839) in inode 1476116.  CLEARED.
Special (device/socket/fifo/symlink) file (inode 4751932) has immutable
or append-only flag set.  Clear? yes

... TONS OF LINES ...

Inode 28966974 has illegal block(s).  Clear? yes

Illegal block #1 (3644916482) in inode 28966974.  CLEARED.
Illegal block #2 (150118149) in inode 28966974.  CLEARED.
Illegal block #3 (1090716163) in inode 28966974.  CLEARED.
Illegal block #4 (4087285209) in inode 28966974.  CLEARED.
Illegal block #6 (2667960641) in inode 28966974.  CLEARED.
Illegal block #8 (98124035) in inode 28966974.  CLEARED.
Illegal block #10 (3644916482) in inode 28966974.  CLEARED.
Illegal block #11 (150380293) in inode 28966974.  CLEARED.
Illegal indirect block (1090716163) in inode 28966974.  CLEARED.
Illegal double indirect block (4154394073) in inode 28966974.  CLEARED.
Inode 28966974 is too big.  Truncate? yes

Block #102763539 (768) causes directory to be too big.  CLEARED.
Error storing directory block information (inode=28966974, block=0, num=3215973): Memory allocation failed

after a long time e2fsck ends but the problem remains.
I don't know if this may be the source of the problem... but insted 'normal' ext3 partition I have lmv.

# fdisk -l /dev/sdb

Disk /dev/sdb: 250.0 GB, 250000000000 bytes
255 heads, 63 sectors/track, 30394 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe990e990

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1       30394   244139773+  8e  Linux LVM

Bellow some information about lvm system:

# lvmdiskscan
  Incorrect metadata area header checksum
  /dev/sdb1 [     232.83 GiB] LVM physical volume
  0 disks
  0 partitions
  0 LVM physical volume whole disks
  1 LVM physical volume

# pvdisplay
Incorrect metadata area header checksum
"/dev/sdb1" is a new physical volume of "232.83 GiB"
--- NEW Physical volume ---
PV Name               /dev/sdb1
VG Name              
PV Size               232.83 GiB
Allocatable           NO
PE Size               0  
Total PE              0
Free PE               0
Allocated PE          0
PV UUID               AEEN6h-tCQ2-rGmL-NdCa-JQSY-puP9-6D6sCU

It seems that all information about my old lvm(VolGroup00/LogVol02) was lost?!?! I have no experience with lvm stuff. Please, any help will be appreciated.

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#2 2010-04-09 15:50:00

g2g591
Member
Registered: 2007-12-24
Posts: 54

Re: "superblock could not be read" + lvm2

you ran mkfs and fsck on the WHOLE LVM, not the actual lvm partition, not /dev/VolGroup00/LogVol02 like you should have. hate to say it but I think you kinda hosed your datas there.

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#3 2010-04-09 17:36:45

jesoliveira
Member
Registered: 2010-04-08
Posts: 2

Re: "superblock could not be read" + lvm2

Thank you for your reply.

sad to hear that...

but if I remember correctly, even in the begging of the problem I was not able to find /dev/VolGroup00/LogVol02 anymore, so I've tried vgcfgrestore and other stuff; latter on I've tried fsck on /dev/sdb1.

by using testdisk, I could see something:

Results
     Linux                    0   1  1 30393 254 63  488279547
     EXT3 Large file Sparse superblock Backup superblock, 249 GB / 232 GiB
     Linux LVM                0   1  1 30393 254 63  488279547
     LVM2, 249 GB / 232 GiB
     HPFS - NTFS          12111   1  1 30392 254 63  293700267
     NTFS found using backup sector!, 150 GB / 140 GiB

Is it possible recover the data? I saw on internet people reporting success by using explore2fs under windows.

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#4 2010-04-12 13:03:45

g2g591
Member
Registered: 2007-12-24
Posts: 54

Re: "superblock could not be read" + lvm2

explore2fs doesn't support LVM unfortunately hmm I think its pretty well gone, doing the mkfs and all the changes e2fsck did to it. I recently had a loss with LVM recently myself... it makes data recovery just that much harder... at least it didn't eat my /home in my case

Last edited by g2g591 (2010-04-12 13:04:38)

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