250GB - cache
1TB - Pool
2TB - Pool
10TB - Parity

With only 3TB in the pool you’re going to be increasing the size of the pool potentially quite quickly depending on if you’re ripping DVDs or Blu-Rays to it.

You’ll soon need another drive to boost that pool size and I promise, that parity will keep those tears at bay if something happens.

And shouldn’t be so tall that you need a winch to get over them without trashing the bottom of your car like the new ones near to where I live.