I have got a chassis with the Supermicro BPN-SAS3-826EL1 backplane. This backplane allows 12 HDDs to be attached. However, I obviously haven't yet understood the cabling between the HBA and the backplane which I need to actually use all 12 HDD ports.
According to the first drawing on page 3-1 in the manual, PRI-J1 and PRI-J2 should be connected to the HBA (and thus are "inputs"), while PRI-J3 and PRI-J4 are "outputs" which can be connected to a cascaded backplane, which I don't have.
The manual further says that PRI-Jn are SFF-8643 connectors, which can transport the signals for 4 SAS or SATA drives. That means that I can use 8 HDDs with the backplane, although it mechanically provides 12 drive connectors.
What do I need to do to use 12 HDDs with that backplane?
Please forgive me if the question is dumb, but I have no experience with backplanes yet, and I have studied this and other Supermicro manuals several times, but still don't understand the situation.
Update / Clarification
I am very sorry that I have not been clear enough:
I'd like to use SATA drives (not SAS), and I already have a LSI 9361-8i connected to the backplane, using two cables with SFF-8643 connectors at each end. That way the controller is seeing 8 drives. Now I'd like to know how I can use the remaining 4 drives.
The board I am using has two SATA / SAS controllers integrated, each of which can handle four drives. Do I just need to connect one of them to PRI-J3 of the backplane?