Powervault MD12XX Split Mode No Drives Showing on EMM1

Hi,

I have two Dell R720s with the 6Gbps SAS HBA's both connected to a Powervault MD1200 and MD1220 both with dual EMMs and both configured in split mode. The drives are also split half on bays 0-4/6-10 for the 1200 and half on bays 0-5 and 12-18 (yes 7 disks) on the 1220. Effectively I'm looking to split the storage as JBODs on both servers. Both PVs are in split mode when started and the light on the front indicates split mode. I wait about 10 minutes after powering up the PVs to power up each R720 in sequential order. The EMM lights are green, the SAS connectors on the HBAs are green on both the PV and R720 sides.

But....

When I enter the SAS controller's BIOS to look at the configuration, for the connections into the EMM0 of both PVs, I can see both enclosures and ALL of the drives as I expect. But for the connections into the EMM1 of both PVs, I can see both enclosures but NO drives. 

Now, I could see many one of the EMMs being faulty or something, but two independent ones on two different PVs? I feel like I'm doing something obviously wrong.

Note that if I flip the connectors such that the other R720 gets the EMM0 ports, it works there. So I've ruled out both a cabling and SAS card issue.