I can tell you for sure, it works. I am fairly certain it is supported. Not sure why it would not be.ALL filers today use Software Ownership of disks. All platforms.
If you boot up one unit into maintenance mode: disown all disks. Halt
Boot the other node into maintenance mode: disown all disks.
Now, you can use some command to:
disk assign xxx 12
where xxx is some combination of disk size, disk type, etc...defining which disks.
The 12 is the number to assign. It will pick 12.
Then you can do the same (or disk assign all, since 12 would be left)
Then you can configure and go.
I do this now. You must/should turn off the disk auto-assign function.
For the record, the slot 1/2 thing was during the hardware ownership and it read a
special section of the disk where the OS was stored.
Todays software ownership systems boots off an internal flash drive
only using the disks for storing configuration.
I have a 4-node Clustered Ontap 8.2 system built this way.
I started from scratch, zeroed all disks, Attached one shelf to a pair
and then assigned disks. I grew them until all the disks were spilt evenly.
Since the disk-auto-assign is disabled and since no head owns all the disks in
a shelf, I must assign the disk to head when I replace a failed disk.
Not a big deal.