Use a Centos or Debian Live CD because when you are attempting a rescue you don't want the additional stress of hunting down needed but potentially obscure packages, you just want to be able to get them easily, do the job and finish. The package we need here is lvm2 which is in both Centos and Debian repos.
So first download Centos 6.4 Live CD iso or Debian Live CD iso and burn it to a disk or put it on a USB stick. (Not described in this post).
Once done, boot from it, whether disk or USB and once you are in the live environment you can bring up the terminal emulator or use the console, run fdisk and list the available drives. UseCtrl+Alt+F4 to stop X server and go to the console. The live disk uses sudo for root access.$ sudo fdisk -l Device Boot Start End Blocks Id System
/dev/sda1 * 1 3891 31254426 7 HPFS/NTFS
/dev/sda2 3892 3955 512000 83 Linux
/dev/sda3 3955 38914 280803328 8e Linux LVM
The sda3 entry is not suitable to mount in the normal manner because you do not have the correct path, so you need to do a little more probing to find this.
First install the tools package with apt
$ sudo apt-get install lvm2
And issue the command to find the LV Group which is under VG
$ sudo pvs PV VG Fmt Attr PSize PFree /dev/sda3 vg_centos lvm2 a-- 267.79g 0 'vg_centos' is fine to start with, but we need a little more.
Issue the command to display the directories and path.
$ sudo lvdisplay --- Logical volume ---
LV Path /dev/vg_centos/lv_root
LV Name lv_root
VG Name vg_centos
LV UUID tiDVyK-ct0t-8GOJ-UuRn-uDWI-95jX-bqQWfy
LV Write Access read/write
LV Creation host, time Centos, 2013-04-21 20:13:14 +0100
LV Status available
# open 1
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Path /dev/vg_centos/lv_home
LV Name lv_home
VG Name vg_centos
LV UUID yUzkjk-RMk0-0k77-NCkh-l2WB-y0So-gMzjDT
LV Write Access read/write
LV Creation host, time Centos, 2013-04-21 20:13:29 +0100
LV Status available
# open 1
LV Size 211.84 GiB
Current LE 54231
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2You will probably have a swap also but above just shows the directories we are interested in. The LV Path is what we use to mount the Logical Volumes, and nowwe have the full and correct path, they can be mounted as normal, we just need a directory to mount them into, so create a newroot directory. (As unprivileged user or root)$ sudo mkdir newroot
$ sudo mount /dev/vg_centos/lv_root /newroot$ sudo mount /dev/vg_centos/lv_home /newrootDepending which directory you want to access. Use vgchange to make them active
$ sudo vgchange -a y
3 logical volume(s) in volume group "vg_centos" now active
Now you can navigate to the /newroot directory either in the terminal or using the file manager and access the file you need to fix, replace or delete.Straighforward mounting of the Volume Group in Centos 6 usinga Live CD.Using chroot
Use chroot if necessary as in the image below, doing this and then running the mount command shows the newly mounted volumes for the 'damaged' system as they appear in the newroot directoryTest already mounted volumes
You can test what is mounted by using one of below as root
# df -H
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
53G 5.5G 45G 11% /
tmpfs 3.2G 0 3.2G 0% /dev/shm
/dev/sdb2 508M 33M 450M 7% /boot
/dev/mapper/vg_centos-lv_home
224G 9.0G 204G 5% /home
# mount
/dev/mapper/vg_centos-lv_root on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
/dev/sdb2 on /boot type ext4 (rw)
/dev/mapper/vg_centos-lv_home on /home type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) 
