im not sure. i just want somthing that is reliable and can hold alot of data. i currently have 15tb worth of data on my pc. im looking into free nas because of its zfs file system.
Usable space for an 8 drive RAIDz1 Vdev of 6TB disks = 33TB or 30TiB (not recommended for this size disks)
Usable space for an 8 drive RAIDz2 Vdev of 6TB disks = 28TB or 25TiB
Usable space for an 8 drive RAIDz3 Vdev of 6TB disks = 23TB or 21TiB (more redundancy, less space obviously)
I think the RAIDz2 would give you the best usable space option,
with two Vdevs that totals 56TB of USABLE space (pool not over 80% full)