For maximum storage capacity and resiliency, create six 1.1 TB VMDKs from the two datastores and attach them to the SoftNAS® VM. This results in six virtual disks of 1.1 TB each becoming available within SoftNAS®.
Inside SoftNAS®, add all six virtual disks to a single, large storage pool using RAID 5 (single parity). The advantage of using both hardware RAID 6 is the arrays can tolerate up to two concurrent drive failures on each array. The software RAID 5 then provides an added layer of parity and recoverability.
Effectively disable software RAID within SoftNAS® by specifying RAID 0 (no redundancy, with striping) and assign all six 1.1 TB virtual disks to a storage pool. Please note that if hardware RAID is used, combined with RAID 0 in SoftNAS®, the built-in ZFS filesystem will be unable to recover data, as it will have no parity information to work with. As a result, as with any hardware RAID system, data integrity is reliant upon the hardware level RAID array and its integrity alone.
Alternatively, place the hardware controller into "JBOD mode" and just pass each disk through to SoftNAS® directly as raw storage (no hardware RAID), and use the software RAID within SoftNAS® to handle RAID.
It is important to give careful consideration to which type of RAID configuration will be used to provide the right balance of performance and resilience for applications.