When checking my cloned Ubuntu 14.04 LTS VM, I noticed that it still contained the volume group name from the original, which is of course not desired.
It seemed fairly simple, but I kept receiving an error with update-grub, reporting the old Volume Group name:
/usr/sbin/grub-probe: error: failed to get canonical path of `/dev/mapper/<Old VG>-root'.
Steps to be done as root:
#Show the current VG name
#Proof that it really is used
>ls -als /dev/mapper/
#Do the rename
>vgrename -v <old VG> <new VG>
#Replace all references to the old VG with the new ones in fstab:
#This will give an error as Ubuntu 14.04 LTS still finds the old VG name (no idea why)
#So, replace all references directly in the one that is going to be used in the next reboot
#This command does nothing
#This shows that the VG really is renamed
>ls -als /dev/mapper