Any use connecting SAS3 HBA to SAS2 backplane?

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FlashEngineer

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Jan 27, 2016
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I will get a motherboard with onboard SAS3 HBA, in my supermicro SC847 that has SAS2 backplane. Does this improve transfer rate or not?
 

T_Minus

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Feb 15, 2015
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Need more info... but generally SSDs in a non-expander backplane will benefit from a SAS3 HBA over SAS2.
 

FlashEngineer

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Jan 27, 2016
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The backplane is the BPN-SAS2-EL1 (hence SAS2 6.0gbps)

The MB has SAS3 HBA onboard via Broadcom 3008

If I used the HBA onboard vs the M1015, is there any difference?
 

T_Minus

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Feb 15, 2015
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Well first off, that's an expander backplane from my quick google search so you're going to be limited to the single port for ALL drives connected, combined... as-in you won't come near to maxing out SSD performance based on total # of drives in use.

Is a SAS3 HBA > than M1015 ... yes, but again if you're using spinning drives on an expander backplane it's likely not worth it.

If you've got 24x SSD in there you need a non-expander backplane with 6x SAS connections and 3x HBA to get the 'best' you can with 6 ports.
 

FlashEngineer

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Jan 27, 2016
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Yeah for sure if I was using SSD, but it's just spinning drives and they are all 6.0 Gb/s

I guess my question is that, using the SAS3 HBA, is it still 4x lanes x 6.0Gb/s into the backplane or is it 4x 12.0Gb/s since it's SAS3? THen at least the 24 drives will have 2.0Gb/s per drive vs 1.0Gb/s
 

i386

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Mar 18, 2016
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4x 6gbit = 24 gbit (2.4gbyte/s)
double for dual link (two cables from the hba/raid card to single expander)