LSI 9240-8i strange behavior: picky about backplanes

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TurboFEM

New Member
Aug 27, 2020
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I have an unusual problem with my Lenovo TS440 server.

I am trying to use an LSI 9240-8i card (that is flashed to IT BIOS) to connect to a new-to-me 8 x 2.5" SAS/SATA backplane (FRU 03T8869) currently populated by 4 SATA drives. The backplane is connected to the card via two (FRU 03x3988) mini-SAS cables. The backplane is powered by the PSU Conversion board (FRU 03T8876). The card will not see the drives.

I have established that the card, cables and the PSU conversion board are in good working order, by trying them all on a different, known good, 4 x 3.5" backplane that originally came with the server, which I am trying to replace. This was successful - i.e. the 3.5" drives are visible to the card (to both slots, using any of the two mini-SAS cables) and everything works as expected.

I was about ready to throw away my 2.5" backplane, thinking it was defective, when I decided to try one last thing: I connected the 4xSATA-to-SAS breakout cable I have (FRU 03x3989) to the SATA ports on the motherboard, and the SAS end of the cable to one of the ports on the backplane, and loo-and-behold - 4 drives are now visible in machine's BIOS (they boot the OS and work as expected).

So, I am a bit puzzled now:
  • The LSI card seems to work (verified on the 3.5" backplane)
  • Both SAS cables seem to work (each verified on the 3.5" backplane)
  • PSU conversion board supplies power correctly (powers on both 2.5" and 3.5" backplanes w/o problems)
  • 2.5" backplane seems to be working (at least with the SATA-SAS breakout cable, up to 4 drives obviously, connected directly to the MB)
  • Ultimately, the combination LSI + 1xSAS cable + 3.5" backplane powered by PSU conversion board works
but
  • the combination LSI + 1 or 2 x SAS cable(s) + 2.5" backplane powered by PSU conversion board doesn't work.
If anybody has an idea what might be going on, please help.