the 1 tb hdd is for backup and the 4 tb hdd are for storage
I had a 960 gb ssd that was the same price as the 1tb ssd I have now so I switched it
just buy a usb stick or something later or partition the 4tb drive
having an entire extra 1tb just for backup isnt worth it
since you have so much space on the ssd anyway just back up on it aswell if its that much of a concern
or just make a folder of everything thats important and use any of the cloud storage solutions around