repair lvm superblock

tuxsea · 01-09-2013, 12:28 AM

Hi. I have an lvm partion with two volumes (/home and /) with no space unallocated. Since I needed more room for / i shrinked /home 1G and extended / both using system-config-lvm. But when i reboot i saw something like this

Code:

 ext4_check_descriptors: Block bitmap for group 577 not in group (block 18918726)!
group descriptors corrupted!
run e2fsck -b 32768
...

i restarted again with a fedora12 livecd, root mounts fine. I found some information, but since its my /home and don't have any backup, cause that's how my brilliant self rolls :fp: I wanted to do an image of the partion at least, with d3dd or ddrescue but they both have to perform fsck and i don't want to screw it i also read its not so bright triying to image a damaged partition so i'd like someone to guide me into which is the safest bet, please

As far as i tell i should be using vgcfgrestore, however will it restore both volumes to their original size or will it fix whatever is wrong with the /home volume. where to begin?

http://blog.adamsbros.org/2009/05/30...thout-backups/
http://forums.fedoraforum.org/archiv.../t-162893.html
http://]http://www.linuxquestions.or...l-size-497534/
https://bbs.archlinux.org/viewtopic.php?id=141904
http://www.cyberciti.biz/faq/recover...ted-partition/
http://www.linuxquestions.org/questi...taloss-557746/
http://www.linuxquestions.org/questi...th-lvm-637951/

Thanks!

syg00 · 01-10-2013, 03:10 AM

Quote:

Originally Posted by tuxsea

... i also read its not so bright triying to image a damaged partition so i'd like someone to guide me into which is the safest bet, please

This is one of the few occasions when you really want to use dd itself.
Take an image of the disk and play around with that. If it all goes to hell, copy it again and try something else. I'm surprised the GUI tool would mess up, but I wouldn't use it myself.

Then again, I'm anal about backups - especially when screwing around with partitions that contain data I care about.

tuxsea · 01-17-2013, 08:41 PM

Hi I haven't fix this yet. I set up a vm but i've been unable to reproduce the bad superblock error. I did however resize the logical volume but not the fs and partially fix it with vgrestore.
So can someone help me to reproduce the error, also what's the difference between /etc/lvm/archives and /etc/lvm/backup?
Thanks

rknichols · 01-17-2013, 11:11 PM

The "backup" directory contains a listing of the current configuration of each volume group. The "archives" directory contains up to 10 (by default) previous versions of the listing for each volume group.