I have an AVS 10/4  that is running 8x4 Tb disks. If I wanted to add a 6Tb disk to the array,I would actually net 4Tb as the new 6Tb drive needs to be parity. Is that correct?

When I add a 6Tb disk to the array, what would be the proper procedure?

 

Here is a screenshot of my configuration:

http://i.imgur.com/Su7HCxE.png

Sounds like you want to upgrade parity and use the old parity as data. The "normal" way would be to rebuild parity to the larger drive then preclear the old parity and add it to a new slot, but there is actually a shortcut way to do this. See bjp999 sig. Post back if you need further explanation.