I'm looking to upgrade my motherboard and HBA card, and want to ensure I'm picking a good one.  Currently I seem to have a bandwidth bottleneck somewhere since during a parity rebuild, I get about 1.5 Gb/s total thru put.  I have an LSI 9211-4i card (4 PCIe 2.0 lanes) which is connected to the backplane via a SuperMicro "CBL-0108L-02" SFF8087 to SFF8087 cable.  The backplane is a SuperMicro BPN-SAS2-846EL1.  All of this hardware is supposed to support 6 Gb/s, so is the bottleneck the 4 PCIe 2.0 lanes?  The 4 PCIe 2.0 lanes should be 2 Gb/s?

 

I'm also looking to get a new case and it comes with a 12 Gb/s SAS/SATA expander backplane.  So it seems I will need a motherboard that has PCIe 4.0 8 lane.  Is there even an affordable HBA that is PCIe 4.0 8 lane?  If that's not really worth it, should I just go with the 6 Gb/s backplane?

 

Thanks.

30 minutes ago, nerbonne said:

I get about 1.5 Gb/s total thru put. 

Assuming you mean 1.5 GB/s that's about the expected, 2GB/s is the theoretical max, you'll never get that, usually you'll get 75 to 80% of that, see below for some more numbers:

 

 

32 minutes ago, nerbonne said:

Is there even an affordable HBA that is PCIe 4.0 8 lane?

Not really, but there are PCIe 3.0 models, and those are good for about 4GB/s with a single link, 6GB/s with dual link.

Thanks for the help!  Looks like the easy answer is to install a LSI 9211-8i and I will double my PCIe 2.0 lanes from 4 to 8, which will double my PCIe bandwidth from 2GB/s to 4GB/s?

 

Yes, with about 3GB/s usable, 2.2GB/s if connected to an expander with a single link.