# create swap partition on /dev/vdb
###################################

# create PV,VG and LV
lsblk 
fdisk /dev/vdb1 
pvs
pvcreate /dev/vdb1 
vgcreate vgswap /dev/vdb1
vgs
lvs
lvcreate -n swap -l 100%FREE vgswap 
ls /dev/mapper/vgswap-swap 

# format LV as swap
mkswap /dev/mapper/vgswap-swap

# add swap entery in /etc/fstab 
/dev/mapper/vgswap-swap swap swap defaults 0 0 

# activate swap
swapon -va

# check swap
cat /proc/swaps
free -h