@MontyD, I hate to say it, but you really seem to have a problem with the most basic of troubleshooting. You're getting a message saying "this is a freenas data disk and cannot boot system." How could that message be clearer? It's telling you that the disk the system is trying to boot from is a FreeNAS data disk. Since that isn't what you want to happen, you should readily be able to deduce that the system is trying to boot from the wrong device.
It's critical that you read what the system is telling you, think about it, and respond accordingly. Your posts over the last day or two do not demonstrate this ability. There will be many things in the course of administering a FreeNAS system (and really, most computer systems) that will need more than the ability to follow specific steps.