It is confusing that a logical volume can contain either a partitioned drive or a single file-system with no partition table. Doing an fdisk -lu will determine which.
A partition can contain several file-systems, such as boot and a “nested” LVM partition. The link at the bottom gives examples of how to access this.
Create and mount a LV
/usr/sbin/lvcreate -L 20G -n jessica VolGroup00
/sbin/mkfs -j /dev/VolGroup00/jessica -L jessica #format jessica as ext3
mkfs.ext4 -L ext4volname /dev/vg/newvol # or ext4
mount /dev/VolGroup00/jessica /home/jessica/backup