SOLVED Supermicro mini SAS HD will not deal with SAS drives

[prosecco]

Hi guys,
I am trying my first FreeNAS build. First mistake, I thought that my Supermicro motherboard supported SAS drives.
The onboard mini SAS HD can manage 8 SATA drives.
I already bought 8 SAS drives.
So I understand that I need a HBA SAS card, but the thing is that I only have a PCIe x4 onboard.
Is there any 12GB/s card out there that will manage 8 SAS drives and work with FreeNAS?

 

[Johnnie Black]

Is there any 12GB/s card out there that will manage 8 SAS drives and work with FreeNAS?

LSI 9300-8i

 

[sretalla]

@Chris Moore is the maestro on this topic. (but he will probably challenge you on why you need 12Gb/s)

I'm not sure you will find something that isn't 8x due to the bandwidth needed.

LSI 9300-8i

This card is an 8 lane card... https://www.broadcom.com/products/storage/host-bus-adapters/sas-9300-8i

 

[Johnnie Black]

This card is an 8 lane card

Yep, sorry, missed the x4 slot, most 8 ports HBAs are x8

 

[prosecco]

Thanks guys. Yeah I already searched for LSI cards but they are all X8.
Well I don't need 12GB/s anymore if it will be impossible.
It's just that with the 2 * 10GB/s SFP+ I thought that it would be nice to have matching speed in theory.
But really Supermicro, why a mini SAS HD won't be able to manage SAS drives? So frustrating!

 

[sretalla]

I'm not sure your workings are right anyway...
https://www.tested.com/tech/457440-theoretical-vs-actual-bandwidth-pci-express-and-thunderbolt/

For PCIE 2.0, you have 5GT (giga-transactions)/s which actually works out in real terms to about 500MB/s for each lane.

For a 4 lane card, that's 2000MB/s.

For a 10Gbit/s network interface, you will have around 1150MB/s, so the fastest you can serve any single client is already that, regardless of teaming.

If you wanted to max out your 2 NICs with multiple clients simultaneously, you would need to factor in the seeking the disks need to be doing to go and get all those different files being served in order to fill your lanes... this will never happen with only 8 spindles. Also remember things like ARC (in RAM, so hundreds of times faster and nothing to do with the controller).

Don't feel so bad about not having a PCIE3 controller.

 

[PhiloEpisteme]

But really Supermicro, why a mini SAS HD won't be able to manage SAS drives? So frustrating!

That is very surprising to me as well.

It's just that with the 2 * 10GB/s SFP+ I thought that it would be nice to have matching speed in theory.

I imagine you mean 10Gb/s? That makes a huge difference in terms of how well your drives can saturate those connections. sratalla is right though, you aren't using enough drives yet to worry about saturating it.

 

[prosecco]

Thanks guys, that's reassuring but I still can't find a PCIe x4 HBA card for 8 SAS drives.
So I will probably replace these SAS drives by SATAs and use my other computer with free PCIe X16 to plug a card for SAS drives...

 

[pro lamer]

other computer with free PCIe X16 to plug a card for SAS drives

Make sure that slot is not-only for GPU... Just a wild guess...

Sent from my phone

 

[PhiloEpisteme]

Thanks guys, that's reassuring but I still can't find a PCIe x4 HBA card for 8 SAS drives.
So I will probably replace these SAS drives by SATAs and use my other computer with free PCIe X16 to plug a card for SAS drives...

FWIW, you can install an 8x card in a 4x slot. You may have to modify the slot itself by cutting the back off of it. I've never done it myself, but I do know that some boards come with PCIE slots with the back of it cut so you can insert a card normally intended for a larger slot. More commonly you'll see boards which have an 8x form factor slot but only actually have pins etc for a 4x slot.

 

[pro lamer]

, why a mini SAS HD won't be able to manage SAS drives

This is just a connector. This small motherboard has no space for a SAS controller IIRC (some FlexATX boards do have both the space and the controller) and they also saved space using a small connector instead four SATA connectors... Small form factor...

Sent from my phone

 

[prosecco]

you can install an 8x card in a 4x slot

I thought about it but what are the results for doing so?
If it is just losing speed, ok. But if it is losing drives connectivity, that's a no no.

 

[prosecco]

This is just a connector. This small motherboard has no space for a SAS controller

Yeah that is what Supermicro told me 2 hours ago.

 

[prosecco]

Thanks guys…
I found that in the Avago SAS 9300 documentation :

The 9300 adapter family supports 8 PCI Express lanes that comply with the latest PCI Express 3.0
specifications. In addition, these adapters are backwards compatible with previous SAS and
PCIe generations through automatic negotiation, and provide SAS data transfer rates of 12, 6,
and 3 Gb/s per lane, and SATA data transfer rates of 6 and 3Gb/s per lane.

Good news then!

 

[PhiloEpisteme]

I thought about it but what are the results for doing so?
If it is just losing speed, ok. But if it is losing drives connectivity, that's a no no.

Check out the PCIe spec regarding how cards are supposed to behave when placed in slots with fewer lanes. In general you can expect slower speeds. I wouldn't expect issues communicating with the drives.

 

[pro lamer]

You may have to modify the slot

After zooming in the picture here https://www.supermicro.com/products/motherboard/Atom/A2SDi-H-TP4F.cfm it looks like this slot might have a cutout already... I haven't checked the manual though...

Sent from my phone

 

[prosecco]

it looks like this slot might have a cutout already..

Yes, already confirmed that on the board itself. Thanks.

 

[prosecco]

Hello guys, I received the LSI Broadcom SAS 9300-8i 8-port 12Gb/s SATA+SAS PCI-Express 3.0 HBA today and a test confirmed a SAS drive access
Just to confirm, this card does not need to be flashed in IT mode, right?

 

[Johnnie Black]

this card does not need to be flashed in IT mode, right?

Correct, it's IT mode only.

 

[prosecco]

Awesome !! Let's get started then. Thank you all.