You need 4 cages to do cage availability with NL (RAID6 6+2)
-- DD -- DD -- DD -- PP --
where D= Data and P=Parity
Technically with 3.1.2 you can force NL to use Raid 5, but I believe they will be removing it (at least from the GUI) in a future release and I would strongly recommend against it as there's a non-insignificant chance it will lead to data loss through either unrecoverable read errors or through a rebuild taking too long on the big slow spindles.
*edit* just noticed you mentioned RAID1/0, with RAID1/0 you can do cage availability with any even number of cages. If you have cage availability you will never have the two mirror copies of a block in the same cage so you can lose an cage without data loss, but if you lose the right two drives you will lose data, also if you lose a drive and the other copy is on a disk with an unrecoverable read error you will lose either that bit of data or the vvol (not sure on implementation details here).
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