This one is fairly straight forward. This is what you need to do if your boot partition should fail and you need to remount  the LVM logical partition in a new machine or once you’ve re-installed Ubuntu on a new boot partition.Make sure the HDDs are recognised.

fdisk –lu

Scan all disks for physical volumes:

pvscan

Scan disks for volume groups:

vgscan

Activate all volume groups available:

vgchange -a y

Scan all disks for logical volume:

lvscan

Now mount the partition to any directory you want:

mount /dev/fileserver/shared /raid/share

Amend fstab to mount persistently if required. See guidance from start of this mini-series.

Useful sources
http://ubuntuforums.org/showthread.php?t=2019935
http://quonn.wordpress.com/2010/12/01/how-to-mount-lvm-partition-on-ubuntu/