Copy Blockchain to HDD

Change to root user
sudo su -

Locate device name for USB HDD
fdisk -l

Start fdisk using UDB HDD - Important!! replace "sdc" with your device name. 
fdisk /dev/sdc

Delete existing partition
d

Write changes to drive
w

Start fdisk again
fdisk /dev/sdc

Create new partition
n
press enter
press enter
w

Format HDD (ext4)
mkfs.ext4 -L "BLOCKCHAIN" /dev/sdc1

Mount HDD
mkdir /mnt/BLOCKCHAIN
mount /dev/sdc1 /mnt/BLOCKCHAIN

Create directories for blockchain data
mkdir /mnt/BLOCKCHAIN/bitcoin
mkdir /mnt/BLOCKCHAIN/bitcoin/blocks
mkdir /mnt/BLOCKCHAIN/bitcoin/chainstate
mkdir /mnt/BLOCKCHAIN/bitcoin/testnet3

Enter your bitcoin directory
cd /home/norm/.bitcoin 
cp -R chainstate/* /mnt/BLOCKCHAIN/bitcoin/chainstate
cp -R blocks/* /mnt/BLOCKCHAIN/bitcoin/blocks
cp -R testnet3/* /mnt/BLOCKCHAIN/bitcoin/testnet3