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

dtrv

Member
Nov 23, 2016
132
21
18
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
304
50
28
I recall seeing some issues using 6gbps cables with 12gbps drives so make sure your backplane > HBA cables are rated correctly.
 

azev

Active Member
Jan 18, 2013
740
212
43
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

Member
Nov 23, 2016
132
21
18
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

cat lover server enthusiast
Jul 7, 2016
2,539
979
113
artofserver.com
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

Well-Known Member
Nov 24, 2018
447
278
63
Denver, Colorado
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

cat lover server enthusiast
Jul 7, 2016
2,539
979
113
artofserver.com
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.
 
  • Like
Reactions: itronin

BLinux

cat lover server enthusiast
Jul 7, 2016
2,539
979
113
artofserver.com
@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.