ONTAP 8.3 further refines how and when disks are automatically assigned. There are now 4 options for the disk auto-assignment policy – bay, shelf, stack and default. For heavy reading, check out the ONTAP 8.3 Physical Storage Management guide.
If “bay” is chosen, disks in odd-number bays are assigned to the same controller, and disks in even numbered bays are assigned to the same controller. If “stack” is chosen, all drives in the same stack are assigned to the same controller, and if “shelf” is chosen, all drives in the same shelf are assigned to the same controller.
Default is an interesting one – on the FAS22xx and FAS25xx, it means “bay”, on everything else, it means “stack”. If you have a single stack on an 8020? Well, you’ll need to manually set the policy to “shelf”.