Create a volume group, and set 16M as a extends.

# 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)