Will a single 8 lane SAS2 HBA be perfectly sufficient for 12 or even 16 HDDs?
I'm looking into two possibilities: either a chassis that can support 12 or 16 disks, or a first chassis that only has 6 or 8 bays, and then down the road I add a DAS chassis with another 6 or 8 bays... I haven't decided yet if I'm going with 6 or 8 disk, but 8-disk chassis are plentiful and affordable, larger... I'm having trouble finding good ones that support good redundant PSUs without already coming with not as efficient or overkill PSUs. I don't think 800-900W, especially if they aren't even "80 Plus", are going to do me any favors.
That said, I'm thinking that perhaps 1x 8-lane HBA may actually be just fine, and I could have a single 4-lane cable go from the HBA to an expander backplane to support 6 or 8 disks, and then take the other cable, take an adapter that slots into an expansion slot and convert that internal cable to an external interface, use an appropriate external cable to a DAS, then reverse that and run that to another 6 or 8 bay expander backplane.
Is that feasible? Or is it a terrible idea and I should just invest in a 12 or 16 bay chassis up front?
I'm just trying to plan out the right motherboard, and I keep coming back to the mITX Xeon D-1528 offering from Supermicro. It has a total of 4 NICs, two gigabit, two 10GbE. The 10GbE, even running with just gigabit, are likely to use a little more power but not significantly, and if I do upgrade a switch later on to support the 10GbE, then that's even better. The reason I have to accept that is because these mITX boards only offer 1 PCIe slot, so that's the HBA and now no more expansion. I'd like to just get a basic used sub-$100 LSI-based HBA like the IBM m1015 or an LSI-branded one, and be done with it.
I'd much rather a FlexATX board, and the one I'm considering, which will cost maybe $200-300 more, has a D-1537, and a 16-lane LSI 2116 is integrated. The benefit to that board, aside from the integrated 16-lane SAS2 part, is it has two 2x PCIe 8x slots AND it's M.2 PCIe 4x port doesn't put the SSD over a hot Aspeed IPMI controller like on the mITX boards, and it supports the full length 22110 form factor though that's not a huge deal.
It only has 2 NICs, as the 2x 10Gb connectors are SFP+. So I'd definitely want/need an Intel 2 or 4 port gigabit ethernet expansion card.
And that 8-core part has a 1.7Ghz/2.3GHz clockspeed (standard/turbo), whereas the D-1528 is 1.9GHz/2.5GHz.
The D-1541 is better than both, though with a 45W TDP vs 35W TDP of the other two (yes yes, that's not everything... moving on). It's about the same price as the D-1537 part, but Supermicro hasn't announced any FlexATX boards with that part yet.
So, as you see, I'm trying to figure out the right combo while minimizing how many extra parts I need to add.