superblock error after resizing logical volume
I'm running Red Hat Enterprise Linux on a Dell PowerEdge 1800 server, RAID 5.
I recently used the Logical Volume manager to decrease the size of one of the volumes (/dev/VolGroup00/home). I unmounted it prior to resizing. But now I get an error when Linux is loading: The filesystem size (according to the superblock) is 3779584 blocks The physical size of the device is 379904 blocks Either the superblock or the partition table is likely to be corrupt! UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY (i.e. without -a or -p options) [FAILED] ***an error occurred during the filesystem check ***dropping you to a shell. the system will reboot ***when you leave the shell I've tried to restore the superblock's backups using the e2fsck -f -b <backup_block> <volume> command, but that didn't work. Is there a way to change the superblock size manually? I was able to edit /etc/fstab to prevent Linux from performing the filecheck on this volume, so I got Linux to load. Now I'd like to resolve the fsck error. Would it make sense to delete this logical volume, create a new one w/ the same name & properties, then restore its data from a backup tape? I'm a little hesitant to delete the volume if restoring from a backup won't work. Also, I'm not familiar w/ some of the options for the lvcreate command (such as the stripes options). I'm pretty much a newbie w/ Linux, but am willing to listen and learn. |
What didn't work with fsck? What's the error?
I think gpart should be able to reconstruct superblocks too, but I'm not entirely sure. |
Recreating Logical Volume resolved the issue
I did finally get this problem resolved.
The root of the problem was that I used Webmin to reduce the logical volume size. Webmin did not reduce the file system size prior to reducing the logical volume size. Just a warning for others out there. Here's how I resolved: 1. Created new Logical Volume (e.g. /dev/VolGroup00/newLV). I used the Gnome Logical Volume Manager, but lvcreate would have worked as well. 2. Mounted new Logical Volume to a mount point Code:
# mount /dev/VolGroup00/newLV /mnt Code:
# lsof /old_fs_mountpoint Code:
# cd /old_fs_mountpoint Code:
# umount /old_fs_mountpoint 7. Restore any directories/files from archive if necessary Code:
# cpio -idvmu /dir_to_be_restored/* < /dev/st0 8. Run fsck to check the volume, and you may even want to reboot. Code:
# umount /dev/VolGroup00/newLV Hope this helps someone else at some point! Just remember that when you want to reduce the size of a volume, reduce the filesystem size first. And don't use Webmin to do it! |
Hi, I'm having a similar problem here with my
filesystem. I'm not getting further help with my problem but since its pretty much the same as this one I thought I'd mention it - Basically my problem is I have a partition/filesystem that I cannot mount. I would like to know how to find the beginning of the partition so that I can recreate it starting from there and then hopefully be able to fsck and mount the filesystem which is still hopefully on it. The culprit filesystem is inbetween 2 mountable filesystems and the set up is something like this below:- /dev/sda11 10G This mounts ok /dev/sda12 50G Doesn't mount, doesn't fsck /dev/sda13 20G This mounts ok I've tried *many* things in order to mount sda12 but nothing seems to work. A recent article I read about how to find the beginning of a partition talked about a reiserfs instead. So, what is the signature on an ext3 filesystem that can be used to search for its beginning, then its simply a matter of seeking it, and copying 50G from there to another partition and fscking that..I guess. If I'm wrong please help me with the right method. I've tried testdisk which couldn't read the files on this partition. I haven't tried gpart yet. It can't even find the superblock in the standard locations like 8193 or 32768. A recent fdisk listing shows:- bash-3.00# fdisk -ls /dev/sda Disk /dev/sda: 122.9 GB, 122942324736 bytes 16 heads, 63 sectors/track, 238216 cylinders Units = cylinders of 1008 * 512 = 516096 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 20318 10240240+ 83 Linux /dev/sda2 20319 30477 5120136 83 Linux /dev/sda3 30478 40636 5120136 83 Linux /dev/sda4 40637 238216 99580320 f W95 Ext'd (LBA) /dev/sda5 40637 44700 2048224+ 83 Linux /dev/sda6 44701 54388 4882720+ 83 Linux /dev/sda7 54389 56326 976720+ 83 Linux /dev/sda8 56327 57295 488344+ 83 Linux /dev/sda9 57296 61170 1952968+ 82 Linux swap /dev/sda10 61171 80546 9765472+ 83 Linux /dev/sda11 80547 99922 9765472+ 83 Linux /dev/sda12 99923 196803 48827992+ 83 Linux /dev/sda13 196804 238216 20872120+ 83 Linux and the same with fdisk -lu shows: bash-3.00# fdisk -lu /dev/sda Disk /dev/sda: 122.9 GB, 122942324736 bytes 16 heads, 63 sectors/track, 238216 cylinders, total 240121728 sectors Units = sectors of 1 * 512 = 512 bytes Device Boot Start End Blocks Id System /dev/sda1 * 63 20480543 10240240+ 83 Linux /dev/sda2 20480544 30720815 5120136 83 Linux /dev/sda3 30720816 40961087 5120136 83 Linux /dev/sda4 40961088 240121727 99580320 f W95 Ext'd (LBA) /dev/sda5 40961151 45057599 2048224+ 83 Linux /dev/sda6 45057663 54823103 4882720+ 83 Linux /dev/sda7 54823167 56776607 976720+ 83 Linux /dev/sda8 56776671 57753359 488344+ 83 Linux /dev/sda9 57753423 61659359 1952968+ 82 Linux swap /dev/sda10 61659423 81190367 9765472+ 83 Linux /dev/sda11 81190431 100721375 9765472+ 83 Linux /dev/sda12 100721439 198377423 48827992+ 83 Linux /dev/sda13 198377487 240121727 20872120+ 83 Linux bash-3.00# e2fsck /dev/sda12 e2fsck 1.38 (30-Jun-2005) Couldn't find ext2 superblock, trying backup blocks... e2fsck: Bad magic number in super-block while trying to open /dev/sda12 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 alternate superblock: e2fsck -b 8193 <device> ( But this gives the same result) Then if you see the test disk log above, it says to try: e2fsck -b 32768 -B 4096 /dev/sda12 But I get the same result. But the main reason why all this is happening is because i wiped out the first 512 bytes of the damn disk without knowing the repurcursions. That beckons another question. Where can I find a backup copy of the partition table in Fedora core4? Many thanks! |
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