Scrub it... regularly
Yup RAID6 or mirrors are smart, but there is one thing to remember - especially with using larger capacity or SATA drives in any RAID: DO regular routine parity / mirror block checks!
One of the (behind the scenes) features you see in the enterprise arrays (and Linux software arrays from the major distros nowadays) is a background parity raid scrubbing feature or at least a periodic scan during off hours. Extra parity bits (RAID6) or mirrors are definitely a good thing - but there is absolutely no replacement for occasional background reading of all blocks on your arrays. I can't begin to explain the number of times I've seen small raid rebuilds "fail" due to a bad block that accumulated over time but wasn't scrubbed when there was another disk to rebuild from. Data can be corrupted due to noise / vibration / or just bad luck. You don't want to find out about parity block 45698 being bad when the rebuild kicks off due to a real disk kicking the can.