How do you guys use your secondary HDD or SSD?

Solution
Fastest disk for OS and most essential programs and second (and third and fourth in my case) one(s) for installing programs that can't fit in OS drive and others ranging from storing other files while fourth one (and some external ones) for backups.
Fastest disk for OS and most essential programs and second (and third and fourth in my case) one(s) for installing programs that can't fit in OS drive and others ranging from storing other files while fourth one (and some external ones) for backups.
 
Solution