Typically, I discourage buying used drives. In fact, I normally extend that advice to "don't buy anything that's not a ...
If you're using slower drives I would probably go RAID1 (OS) + RAID10 (DB) in your situation - but you would also want a hot spare (at least a cold spare) so you're talking 7 drives there. If you are ...
That’s why you’ll often hear home lab enthusiasts and data-hoarders (including yours truly) mention the importance of extra ...