With this massive amount of data, probably running in production environment, and you want both performance and stability, in my oppinion, you must at least have
- 2 volumes (data+log and temp)
- set each volume up as raid 0+1 (stripe+mirror) as a minimum (preferably hardware raid)
- have a great backup (and restore) plan
If each volume should hold 12 TB, that would require 3x6 TB disks (per volume).
If you want even better performance, other raid plans can be implemented (by the cost of more disks and probably other raid controllers).
But you should consider this: can you afford downtime if one disk fails? or more disks (you would have to consider better raid than 0+1 for this)?
I would personaly choose stability over performance, if I had to choose.
Spanning disks is a no go in production server, in my opinion, as this will get you no performance nor stability.