I know this is OT for this forum, but it is tangentially related, so I'll try my question here:
For 1080p30 editing applications where reliability is paramount, and quantity of storage is not as crucial, which do you recommend: mirrored RAID 5's, or a single RAID 6? Does mirroring cause too much of a performance hit -- more than RAID 6 does?
With RAID-6, you can lose 2 drives within the array before your data is gone. On the other hand, with 2 RAID-5's mirrored, you could lose an entire array and one drive in the second array. Given an unlimited budget, I'd run a stack of four 4TB-based 8 drive arrays - each as RAID-6. I would then stripe two arrays into a pair and then mirror each striped pair.
More redundancy is ALWAYS better. Your real limitation in this realm is budget.
However, this would fall into the realm of serious overkill unless you were forced to use questionable drives in the arrays.