Starting LVM manually
In order to do an fsck you must unmount the filesystem you'll be checking. If that filesystem happens to be your root filesystem then you need to boot from a Fedora Core install CD and boot into rescue mode. You need to answer "no" when prompted to locate and mount Linux file systems. Once the shell is up you need to enter "lvm vgchange -a y --ignorelockingfailure" to start LVM and make the logical volumes available. The "lvm" command may also be "lvm.static".