Non-destructively running fsck
Hi,
I have an ext3 partition that became corrupted after an unclean shutdown (the power cut). My machine no longer boots and using Knoppix, when I try to mount the root partition, it gives me the following message: mount: wrong fs type, bad option, bad superblock on /dev/sdb1, or too many mounted file systems Is there any way to run fsck so that it writes changes to the filesystem into a temporary file and doesn't actually change the real filesystem so that I know what fsck will do to the partition (I've had experience with fsck where it hosed the filesystem) and know is the fsck operation will leave my data intact? I know I can do this by dd'ing the partition, but sometimes, it's not practical to dd a 50+ GB partition. Thank you for your help. |
How about using the -N switch, and >> to a file? (of course make sure the file is on another drive or whatever)
So like fsck /dev/hda6 -v -N >> tempfile.txt v = verbose, and N = Don't actually do it, just show what would be done. NOTE: read 'man fsck' to be sure for yourself that this exactly is what you want. |
Thanks GrapefruiTgirl. Do you know if this would then allow me to mount the filesystem afterwards to see if any damage had been done? I get a feeling that -N would just show you what would be done but wouldn't allow you to mount the filesystem afterwards. Any ideas?
|
Well.. I'm no expert by any means, but... If it's the root filesystem, it will automatically run fsck during boot, to fix it.
Mounting it and having a look around, you might not really be able to see any damage yourself. It might 'look' fine, but still have errors somewhere. If you want to mount it, boot a live CD or load another OS on your machine, then mount this messed up partition 'Read-Only' and then CHROOT into it. Again, as far as mounting it in the circumstances that it is the root partition of a system which you are actually booting, it's going to want to run fsck. There *might* be a flag you can set on either fsck or on reboot that will skip fsck, but I can't recall if/what it is. Success stories vary, but personally I haven't had anything go terribly wrong with fsck; I haven't lost any data or files, with the exception of stuff like the open status of my browser for crash recovery, or files I have had open in 'kwrite' when I rebooted, that sort of thing. But, I use Ext2 and e2fsck. Don't know what difference it makes, but, that's just my own experience. Why not just TRY what you want: run fsck -N and then remount it RO or RW, and see what happens? :) |
All times are GMT -5. The time now is 08:40 AM. |