Limits on SAS speed Supermicro Backplane BPN-SAS-826A

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dtrv

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Nov 23, 2016
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I wonder what the maximum SAS speed of Supermicro's A-Backplanes is. Currently I have SAS-3 HDD's (12 GBit/s, HGST 10TB) on a Supermicro Backplane 826A that is attached on SAS-3-HBA LSI SAS9300 (flashed IBM M1215, IT mode).
ZFS throws alot of errors while reading data and I see increasing ECC error log counter of the HDD's. I never saw errors while writing data.
There are other SAS-2 drives (6 Gbit/s, HDD's and SSD's) attached without any problems.

I was wondering if the backplane is not capable of SAS 12 GBit/s speed. Documentation of the backplane does not say anything about speed. Only the product pages of Supermicro servers with this backplane says "SAS 6Gbps direct-attached backplane".

Could there be any incompatibilities between this HDDs and Backplane/HBA?
Does anyone know how to reduce SAS speed to 6 GBits/s without changing the hardware? Or any hints?

I already changed the cable and replaced a HDD with one of the same type and firmware (HUH721919AL4200).
 

sth

Active Member
Oct 29, 2015
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I recall seeing some issues using 6gbps cables with 12gbps drives so make sure your backplane > HBA cables are rated correctly.
 

azev

Well-Known Member
Jan 18, 2013
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You should be able to go to the controller bios and hard code the sas speed to 6g and see if that makes a difference.
I had similar backplane with 6gb rating and installed 12Gb sas controller & 12Gb sas ssd and it worked just fine.
Another thing to try maybe swapping to different slot in the backplane and see if that fixed it... I had bad port on backplane before.
 

dtrv

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Nov 23, 2016
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Can't find a switch to set SAS speed in HBA's BIOS. It is a flashed IBM M1215, so LSI P19 (?, will check that on next reboot). Did I missed something?
I could try a SAS2008 HBA which is SAS 6 GBit/s by itself.
And I'll swapping to a different slot - good point. That's the easiest one to test.

How do I find out, if my backplane is SAS3 capable? The manual doesn't say anything about speed ...
 

BLinux

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Jul 7, 2016
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i have the same backplane in a Supermicro 846 with HGST 4TB SAS-3 HDDs and LSI SAS2308 HBAs (3 of them) and drives connect at 12Gbps (according to smartctl -a output) and I've run several benchmarks with iozone and did not have the type of issue you mention. the SAS cables I'm using are the 3M flat foldable type.
 

itronin

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Nov 24, 2018
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i have the same backplane in a Supermicro 846 with HGST 4TB SAS-3 HDDs and LSI SAS2308 HBAs (3 of them) and drives connect at 12Gbps
o_O Please share the magic that makes that configuration possible. Or did you mean an LSI 3008?

Love the 3M foldable cables.
 

BLinux

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o_O Please share the magic that makes that configuration possible. Or did you mean an LSI 3008?

Love the 3M foldable cables.
LOL... sorry, you're right. I was thinking of the current setup... not what I had before. I had it setup with a SAS3008 and later a Lenovo 530-8i SAS3408 and it worked fine... but i later realized I don't need SAS-3 just for HDDs and switched it out for SAS2308.

All the Supermicro "A" backplanes have worked for SAS3 for me... i have Supermicro 216 with 24x HGST HUSMM SAS-3 SSDs on a older "A" backplane with the 3408 controllers and they link at SAS3 and I run benchmarks on them without issue.
 
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BLinux

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@BLinux do you have a link to the cables you're using?

The ones I currently have won't even negotiate 12G with my backplane :(
at the distances inside the chassis, i don't think you need any special type of cables. i've used Supermicro branded cables, but i currently use the 3M foldable SAS cables.