Harddisk in my case: Normal NTFS formatted.

Connect the hard disk on your Raspberry Pi.

Login with putty, or open a termal.

sudo blkid
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You see the hard disk name and his location. Something like /dev/sdxX before it. Remember the /dev/sdxX.

Now make a new folder on your pi.
Example: /home/raspberrypi/hardiskmount/

mkdir /home/raspberrypi/hardiskmount/

now typ:

sudo nano /etc/fstab

Add a new rule:

/dev/sdX /home/raspberrypi/hardiskmount/ ntfs default 0 0

Change the X to your own number from the sudo blkid commando on the first step.

Save the file, and close it. (Control + x)

sudo mount -a
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Now navigate to the /home/raspberrypi/hardiskmount/ folder, to use your mounted harddrive!

 

Have fun!