Looking for some guidance on SAS expander hardware

MrHands

Dabbler
Joined
Jan 7, 2016
Messages
18
i have reviewed the hardware recommendations for truenas and it doesnt really mention any requirements for SAS expanders.

Can i throw in any SAS expander? or are there certain requirements such as there are with some NICs that do work, and some that dont.?

I actually have an old Dell H200 Perc 6gb 8-Port raid controller 9210 9211-8i in my old parts box, im hoping this will work to save me some money?

Right now i have 8 HDDs in my pool (that have filled up all my motherboard SATA ports), i have some spare SSDs i wanted to throw in for a second pool as well as another SSD to move Truenas off my old USB and onto an SSD.

Im assuming maybe the older Dell H200 (if it works) may not be suited to SSDs? but i could just move some of my HDDs to the H200, and connect the 3 SSDs to the motherboard SATA.

Lastly, i cant seem to find an answer to this question. Looking on amazon i can only find Mini-SAS to 8x Sata cables. Is mini-SAS the right connector for the internal SAS expander card?

Sorry if this is all very elementary, or if i have missed some guide that details all of this. I have been searching for a few hours and cant find out for definite.

Thank you!
 

Spearfoot

He of the long foot
Moderator
Joined
May 13, 2015
Messages
2,478
Are you wanting an expander? Or a Host Bus Adapter (HBA) card?

Your Dell H200 (assuming it's still working!) is an HBA, and supports up to 8 directly-connected devices (more, if connected to an expander backplane -- see below). These can be SAS or SATA hard disks or SSDs. You would connect them using two "SFF-8087 to SATA forward breakout" cables, like these:


Each cable plugs in to one of the two ports on your Dell card, and supports 4 drives.

It sounds like this may be the route you want to take. With two of the breakout cables, you could connect all 8 of your pool disks to the Dell HBA, leaving your motherboard SATA ports for SSDs, additional HDDs, etc.

Note that it doesn't matter to FreeNAS if you plug some of your pool disks into motherboard SATA ports and the rest into an HBA. You can mix-and-match however you want.

An expander is a different kettle of fish. It's a chip that lets you connect up to 256 devices (though usually far fewer!) via a backplane, connected to an HBA like your Dell H200. These would require a different type of cable.

This is just a rough overview. See @jgreco's excellent SAS resource for more details on all of this stuff:

 

jgreco

Resident Grinch
Joined
May 29, 2011
Messages
18,681
Have you checked out the SAS primer? It isn't clear if you want an SAS expander, which is something that multiplies 4 or 8 SAS lanes into handling a crapton of drives, or an SAS HBA, which gives you (usually) 8 direct connect SAS/SATA lanes.

Assuming either way -

The PERC H200 HBA flashed to IT mode will be fine, it just won't be as fast as possible, because the CPU on it is a bit slower, and the PCIe 2.0 isn't ideal. If you use an SAS expander to attach a lot of SSD's to the H200, it will not perform particularly well, but it won't be broken or anything. Absolutely nothing that you couldn't easily "upgrade" later.
 

MrHands

Dabbler
Joined
Jan 7, 2016
Messages
18
thank you guys this is the information i was looking for.

Sorry i misspoke, it is a SAS HBA, as the two ports on the Dell H200 would give me an extra 8 drives (16 in total with my 8 onboard SATA) which is more than enough right now.

Assuming either way -

The PERC H200 HBA flashed to IT mode will be fine, it just won't be as fast as possible, because the CPU on it is a bit slower, and the PCIe 2.0 isn't ideal.

I will move my HDDs to the H200, and my SSDs to my direct onboard SATA.

Will the H200 with the slower chip, and pcie 2.0 still be ok with 8+ HDDs?

I do have 10gb network, and files transfer on my network around 600 MB/s, may bottleneck that throughput? should i just spend the money on a newer HBA?
 

Spearfoot

He of the long foot
Moderator
Joined
May 13, 2015
Messages
2,478
thank you guys this is the information i was looking for.

Sorry i misspoke, it is a SAS HBA, as the two ports on the Dell H200 would give me an extra 8 drives (16 in total with my 8 onboard SATA) which is more than enough right now.



I will move my HDDs to the H200, and my SSDs to my direct onboard SATA.

Will the H200 with the slower chip, and pcie 2.0 still be ok with 8+ HDDs?

I do have 10gb network, and files transfer on my network around 600 MB/s, may bottleneck that throughput? should i just spend the money on a newer HBA?
Your H200 will work fine with 8 HDDs, and you won't gain anything buying a newer HBA, unless your disks are SAS3 12Gb/s drives.
 

jgreco

Resident Grinch
Joined
May 29, 2011
Messages
18,681
I do have 10gb network, and files transfer on my network around 600 MB/s, may bottleneck that throughput? should i just spend the money on a newer HBA?

Hard drive transfer speeds peak out around 2Gbit/sec (of 6Gbit/sec per lane, so about 1/3rd capacity). This is definitely not a problem for the H200, which is a good HBA, it just kinda predates SSD's being a mainstream thing.
 
Top