Hi there, are you able to confirm that the disks have been partitioned ? i.e. ::> disk show and ::> node run <node name> disk show ?
Do you have any data on this system currently ? If not you can blow it away, unown all disks within the partition menu. The system will then own the disks (odd numbered disks go to one node and even numbered disks go to the other node), partition the disks, zero them and install the OS. This will then give you root and data partitions on each disk making the root aggregate quite small as opposed to using the full disk size.