SOLVED Help Connecting Supermicro Backplane to HBA

devg1

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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
 
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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

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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.
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.
 
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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

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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.
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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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bkj

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Sorry to resurrect an old thread but I have a similar question about the exact same case. I have an 847 with 2 backplanes.

Front 24 bay - BPN-SAS3-646EL1 rev 1.01
Rear 12 bay - BPN-SAS3-826EL1 rev 1.01

The case came with four of the blue mini cables. Two were plugged into the j49 port on the 646L1 and two were plugged into J1 and J2 on the 824. I have a SM AOC-S3008L-L8E. Is it possible to run all 36 drives (both back planes) off the one controller or do I need a second controller? If I can run all 36 do I just plug one cable into j49 and one cable into J1? Or would there be a better way to wire it?
 

jgreco

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See page 2-1 of this:


I have no idea how you could plug two cables into the J49 port; it is a single connector. Did you maybe mean J49 plus J50?

You can hook up an HBA to either J49 or J50, or at your option you can plug two cables in from J49+J50 to your HBA for additional bandwidth. This is absolutely not necessary for hard drives and is primarily useful for SSD's.

If you hook up an SFF8643 to J49, you can then hook up the 12-bay expander to EITHER the other SFF8643 on your HBA OR the other primary SFF8643 on the 24-bay expander (J50). I'm too lazy to look up the 12-bay expander port numbers, sorry. The advantage (for you) to hooking both backplanes directly to the HBA is mainly one of cabling simplicity.
 

bkj

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@jgreco

Thanks for the reply. Maybe I am not talking about the same thing as you. Sorry I am new to HBA's and backplanes. I looked at the link and I def don't have the 51/52 SAS ports it shows as #5 in the pdf. I attached a picture and in my mind I definitely have to cables plugged into port 49. After looking at the close up of the picture the 50 is centered over the ports and the 49 is more on the left port. Maybe thats where I am confused? I am guessing that I could plug the two cables in fron the rear backplane and then plug the cables in 49 ports to the HBA?
 

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jgreco

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You have a 646EL1 expander. The "1" means it only has the primary SAS expander. That mean you would only have J49 and J50 for the primary expander, not J51 and J52 for your nonexistent secondary. See if what I previously wrote makes sense in that light.
 
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