One day it may happen to you that either MBR is corrupted or partition table has gone then you will need rescue mode. However there is one problem,  what if you use LVM in your system. Because redhat does everything for us we don’t actually know what it does for initialization unless you have looked inside the init scripts.

In my rescue environment when I issue “lvm vgdisplay” , I was able to display the configuration but there was no device files under /dev. To overcome this problem do the followings:

The first command “vgscan” scans all disks for volume groups and the second one “vgchange” makes the logical volumes known to the kernel. To deactivate you should but “n” instead of “y” on the command line.

Now you can access logical volumes.