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SOLVED Help Connecting Supermicro Backplane to HBA

Western Digital Drives - The Preferred Drives of FreeNAS and TrueNAS CORE

devg1

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Jul 19, 2019
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5
Hi, I recently purchased a Supermicro SC847 BE1C4-R1K23LPB for a server I am building, yet I am not sure how to connect the drives on the backplane to the HBA I have.
The backplane has 4 ports, but there is space for 24 drives, and I am not sure how to connect them to the two LSI SAS 9305-16i that I purchased. I have all 24 hard drive enclosures filled with SATA drives on the front side, but I don't know how to connect them to the motherboard. I wasn't able to understand the backplane documentation when trying to figure out how to make the connection.

Chassis: Supermicro SC847 BE1C4-R1K23LPB
Motherboard: ASUS Z390-E
Backplane: BPN-SAS3-846EL1
HBA: SAS 9305-16i x2

Picture of SAS ports on backplane:
backplane ports.jpg


Thanks,
Dev
 

Johnnie Black

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May 10, 2017
Messages
825
You have a single expander backplane, you can only connect one HBA, with one (single link) or two cables (dual link) to J50
 

jgreco

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You have a single expander backplane. Take one cable and hook it to J49 or J50. If you read the manual, one may be designated as "in" and the other as "out" but it shouldn't matter. Hook the cable up to one port of your HBA. All done.

You may be able to hook a second cable (x8 wideport) up if you want to try to get more bandwidth out of it, but I've had strange issues with this in the past so I don't suggest it.

The -16i's are pretty useless for this application and you could replace them with a single -8i.
 

devg1

Neophyte
Joined
Jul 19, 2019
Messages
5
You have a single expander backplane. Take one cable and hook it to J49 or J50. If you read the manual, one may be designated as "in" and the other as "out" but it shouldn't matter. Hook the cable up to one port of your HBA. All done.

You may be able to hook a second cable (x8 wideport) up if you want to try to get more bandwidth out of it, but I've had strange issues with this in the past so I don't suggest it.

The -16i's are pretty useless for this application and you could replace them with a single -8i.
So I'd only have to connect one cable from my HBA to to one of the ports on the backplane, and that would enable connectivity with all 24 drives that are plugged in? Sorry if this question sounds stupid, I'm new to building servers.
 

Johnnie Black

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but I've had strange issues with this in the past so I don't suggest it.
Just out of curiosity, was that with SAS2/3? I never had any issues with dual link SAS2, SAS3 and even SAS1, though heard before that SAS1 could be more finicky.
 

jgreco

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And If I were to use double, I'd plug one port on my HBA to one port on J49 and another port on my HBA to a port on J50?
Yes, but this would only matter if you were filling the thing with SSD's.

So even though my HBA has four ports I'd only be using one then? I guess I could've bought a cheaper HBA instead.
That's what I meant when I said you could have gotten the -8i version. :smile:
 

jgreco

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Just out of curiosity, was that with SAS2/3? I never had any issues with dual link SAS2, SAS3 and even SAS1, though heard before that SAS1 could be more finicky.
But did you actually test it, or just hook it up and "it seems to work"?

One of the things that solnet-array-test looks for is variable disk speed. It was intended to spot issues such as bus contention back in the days of PCI and SCSI but still works today to ferret out odd issues. I've seen examples where an x8 wideport was consistently slower than an x4 for no reason we were able to work out, and some other strange stuff as well. It wasn't that it didn't work, it was that the performance was off.

Because an SAS2 x4 is sufficient to handle 12 drives and can probably handle even 24 without a real world contention issue when using ZFS, I've gently guided people away from the x8 which just seems to be opportunity for strange things to happen.
 

devg1

Neophyte
Joined
Jul 19, 2019
Messages
5
Thanks for all the help. Just one last question: which SAS connector do I use, as the chassis's backplate manual has multiple different cables listed. Which is compatible with the backplate? I know the HBA has SFF-8643 connectors, but I'm not sure about the backplate.
1563555222099.png
1563555232023.png
 

Johnnie Black

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Joined
May 10, 2017
Messages
825
But did you actually test it, or just hook it up and "it seems to work"?
I have 3 non ZFS servers using expanders with dual link, for years now, without issues, and the extra bandwitdh is utilized fully for those, though I agree that for ZFS and spinners one link is usually enough for most cases.
 
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