I have Fedora Core 9 installed on a LVM together with ext3 filesystem, and an accidental power outage cause the filesystem corrupted. Here is how I recover it.
- Boot using a Knoppix Live CD
- Press CTRL+ALT+1 to go to terminal 1
- vgchange -a y (Cause all the LVN to be registered with the kernel. Now the logical volumes appears under /dev/mapper)
- fsck -t ext3 /dev/VolGroup00/LogVol00 (possibly fsck -t ext3 /dev/mapper/VolGroup00/LogVol00). Answer y for everything. In the end, it will ask if we want to recreate the journal, say y.
If we don't know anything about LVM (or don't need to use LVM), don't use it.