mount LVM partition from other disk

 Supposed you installed Ubuntu or Cent OS on your machine, you want to mount another LVM paritition disk.
Following is the detailed steps:

2. Boot using the live cd. Search for these tools: lvm2. If the cd do not have it, install it. (Cent OS already installed, Ubuntu maybe not)
# apt-get install lvm2

3. To make sure the harddisk is recognised, you can use fdisk
# fdisk -lu

4. Once installed, run pvscan to scan all disks for physical volume. this to make sure your LVM harddisk is detected by Ubuntu
# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [74.41 GB / 32.00 MB free]
Total: 1 [74.41 GB] / in use: 1 [74.41 GB] / in no VG: 0 [0 ]

5. After that run vgscan to scan disks for volume groups.
# vgscan
Reading all physical volumes. This may take a while...
Found volume group "VolGroup00" using metadata type lvm2

6. Activate all volume groups available.
# vgchange -a y
2 logical volume(s) in volume group "VolGroup00" now active

7. Run lvscan to scan all disks for logical volume. You can see partitions inside the hard disk now active.
# lvscan
ACTIVE '/dev/VolGroup00/LogVol00' [72.44 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol01' [1.94 GB] inherit

8. Mount the partition to any directory you want, usually to /mnt
# mount /dev/VolGroup00/LogVol00 /mnt

more info:
http://linuxwave.blogspot.com/2007/11/mounting-lvm-disk-using-ubuntu-livecd.html