Add lvm partition:
pvcreate /dev/hdc3
---------------

vgcreate vg0 /dev/hdc3

---------------

use withexisting lvm volumes on hd :
lvcreate --name firewall --size 1G vg0
mkfs.ext3 /dev/xen-vol/firewall 
mount /dev/vg0/firewall /firewall

------------------

*RESIZE* LVM
-------------------

lvextend -L12G /dev/vg0/[name]
or
lvextend -L+1G /dev/vg0/[name]

#XFS file systems must be mounted to be resized and the mount-point is specified rather than the device name.

mount /dev/vg0/[name] /mnt
xfs_growfs /mnt
            
----------------------

After hotplugging a harddrive if you want to add the logical volumes:

vgscan
vgchange -ay

-------------

After use:

Unmount file system
Mark the volume group inactive

vgchange -an [volumegroup eg vg0]