CORRECT TEXT
Create a volume group, and set 16M as a extends. And divided a volume group containing 50

extends on volume group lv, make it as ext4 file system, and mounted automatically under /mnt/data.

A.
# pvcreate /dev/sda7 /dev/sda8

B.
# vgcreate -s 16M vg1 /dev/sda7 /dev/sda8

C.
# mkfs.ext4 /dev/vg1/lvm02

D.
UUID=xxxxxxxx /mnt/data ext4 defaults 0 0

Explanation:
# pvcreate /dev/sda7 /dev/sda8
# vgcreate -s 16M vg1 /dev/sda7 /dev/sda8
# lvcreate -l 50 -n lvm02
# mkfs.ext4 /dev/vg1/lvm02
# blkid /dev/vg1/lv1
# vim /etc/fstab
# mkdir -p /mnt/data
UUID=xxxxxxxx /mnt/data ext4 defaults 0 0
# vim /etc/fstab
# mount -a
# mount
(Verify)