if it's still failing, you may not have good connectivity to the disks, check that, and if it looks ok and you want to see it from the OS- you need to stop the boot with control c to get to the loader (this control c prompt is before the control c to load the menu you attached . when the loader shows, type boot_diags and troubleshoot any issues with the shelf connection (can use sysconfig -a command, disk show etc...)
AFF won't recognize spinning drives. That said, according to hwu.netapp.com yes you can use the 2246 with the IOM6 or 12 shelf with various SSD drives only, not SAS. I would put these on a separate stack than any 224c shelves you have.
The non-AFF equivalent of the A300 is the FAS8200 and you can use spinning drives on that model.
Edit: to add, I think the term SAS where you might have been confused in the other posts. SAS is used loosely here, SAS can mean a SAS shelf as they have SAS ports, or a SAS disk. my apologies.