How to mount an LVM volume?

I'm trying to mount an LVM2 volume in Linux, but all the instructions I see online say to mount the Volume Group, such as:

mkdir -p /mnt/VolGroup00/LogVol00

but I don't know how to figure out the name of it. I see the drive in Palimpsest, and that's all the info I know.

Solution 1:

Here are the steps I used to accessing a LVM from Fedora 17, it should work with most forms of Linux.

Boot Fedora 17.

Make sure lvm2 is installed:

$ sudo yum install lvm2

Load the necessary module(s) as root:

$ sudo modprobe dm-mod

Scan your system for LVM volumes and identify in the output the volume group name that has your Fedora volume (mine proved to be VolGroup00):

$ sudo vgscan

Activate the volume:

$ sudo vgchange -ay VolGroup00

Find the logical volume that has your Fedora root filesystem (mine proved to be LogVol00):

$ sudo lvs

Create a mount point for that volume:

$ sudo mkdir /mnt/fcroot

Mount it:

$ sudo mount /dev/VolGroup00/LogVol00 /mnt/fcroot -o ro,user

You're done, navigate to /mnt/fcroot and copy the files and paste somewhere else.

Solution 2:

Faced this problem a while ago, I'd posted this on my blog

List out all your partitions, type

linux:/ # lvmdiskscan

You will get a list of something like this

File descriptor 3 left open
File descriptor 4 left open
/dev/dm-0 [ 9.67 GB]
/dev/sda1 [ 78.41 MB]
/dev/dm-1 [ 6.44 GB]
/dev/sda2 [ 115.52 GB]
/dev/dm-2 [ 2.00 GB]
/dev/sda3 [ 18.11 GB] LVM physical volume
/dev/sda5 [ 15.33 GB]

Make a note of /dev/dm-x, those are the devices which correspond to the LVM partitions. Also do note the sizes.

Next, type lvdisplay to show a detailed list of all the logical volumes available.

lvdisplay |more

LV Name /dev/system/home
VG Name system
LV UUID 1QP9XM-vlKi-umNO-CXvV-TnZN-RCLk-e1FDIr
LV Write Access read/write
LV Status available
# open 1
LV Size 9.67 GB
Current LE 2475
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0

— Logical volume —
LV Name /dev/system/root
VG Name system
LV UUID D1fKUJ-uU1C-jlVB-4imh-rrgy-FQu0-TC2Ssm
LV Write Access read/write
LV Status available
# open 1

LV Size 6.44 GB
Current LE 1649
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1

— Logical volume —
LV Name /dev/system/swap
VG Name system
LV UUID w5LqIb-xvcr-Xsbk-y3wg-lT3i-LqdN-GFK8Mi
LV Write Access read/write
LV Status available
# open 0
LV Size 2.00 GB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2

Now from the above set of data, we can deduce that my /home partition, of size 9.67 GB is available as LV group /dev/system/home on /dev/dm-0

Now that we know where the partition is available, we can proceed with the mounting using the mount command, as

mount /dev/dm-0 /home

And there you go, your LV partition is mounted!

Solution 3:

You can get a list of volume names by running lvscan. The output will look like

/dev/VG1/LV1
/dev/VG1/LV2
/dev/VG2/LV3

i.e. with the volume group names in the middle and logical volumes at the end. See if any of them correspond to the information in Palimpsest Disk Utility.

Also, compare to the list of disks already mounted (mount), and see which one isn't there. It might look a little different, e.g.:

$ mount
/dev/mapper/VG1-LV1 is mounted on /usr
/dev/mapper/VG1-LV2 is mounted on /home

You can see where the volume group and logical volume appear at the end.

Once you've found the right one, mount it in the usual way:

mount /dev/VG2/LV3 /mnt

Solution 4:

I find guestmount(1) the easiest way.

# guestmount -m /invalid/path  -a /path/to/block/device /mnt/
guestmount: '/invalid/path' could not be mounted.
guestmount: Did you mean to mount one of these filesystems?
(...)
guestmount:     /dev/vg0/root (ext4)
(...)

# guestmount -m /dev/vg0/root -a /path/to/block/device /mnt

See also http://libguestfs.org/guestmount.1.html.

Package guestmount on ubuntu, libguestfs-tools on RHEL and derivates.