What to do with second Hard Drive?

[unplanned bacon]

So my rig has two 2 TB hard drives
The C drive is a 7200 RPM WD Black and the 2nd is an unpurposed, but formatted 5400 RPM WD Green

So should I use Green for storage or backup?

 

[IDontUnderstand]

It's whatever you see fit, if you don't need more than 2 TB of storage, then just use it as backup, if you do need the space then it's storage.