You have to increase the RAID Array, so more disks will be needed then use the RAID migration tool from the controller. Then add the new space to the existing Volume Group.
I know this is an old topic, but I've just been able to get back to it. I wiped out my iSCSI unit, rebuilt the RAID array and started completly over. However, when I go to the Volume Group page, it only gives me the option for a new volume group. I don't have any options for a Snapshot volume. Is there something I am doing wrong or have set wrong?