SFF-8087 cables - how many variants, compatibility and quality?

Discussion in 'RAID Controllers and Host Bus Adapters' started by sfbayzfs, May 28, 2015.

  1. sfbayzfs

    sfbayzfs Active Member

    May 6, 2015
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    I have been having problems with a number of SFF-8087 -> SFF-8087 cables between various controllers, expanders, and backplanes. I always seat cables carefully and fully until the latch clicks, yet of the 2 short and 4 long cables that came with my Intel RES2SV240 I bought a couple of years ago, some backplanes and expanders seem to only like to be connected to a controller with either the longer or shorter of those cables, and likewise other cables that appear the same I have gotten both new and used seem to magically not work in some combinations.

    We also had a similar problem at work with a Dell C1100 we were testing at work - when we added an LSI controller provided by Dell to it, the included pair of SFF-8087 -> SFF-8087 cables to connect the motherboard SFF-8087 ports to the backplane were too short, so we ordered a new pair of longer SFF-8087 to SFF-8087 cables, but the controller could never see the backplane or attached drives through the new cables.
    To rule out that some are the wrong type of cable, how may SFF-8087 to SFF-8087 "mini SAS" cables do people here know of? (other than connector angles and locking/non-locking SATA connectors on the other end)

    So far I know of these:
    1. SFF-8087 -> SFF-8087 with sideband
    2. SFF-8087 -> SFF-8087 without sideband (why isn't sideband just part of the spec)
    3. SFF-8087 -> 4x SATA forward fanout - controller or expander to individual drives with sideband connector
    4. SFF-8087 -> 4x SATA forward fanout - SFF-8087 controller or expander to individual drives (no sideband)
    5. 4x SATA -> SFF-8087 reverse fanout - individual SATA/SAS connectors on controller to backplane or expander (I have never seen any of these with sideband connectors, not that I have seen many at all)
    6. SFF-8087 + Molex or SATA power to 4x SFF-8482 SAS w/ power connectors
    7. SFF-8087 + Molex or SATA power to 2x 4x SFF-8482 SAS w/ power connectors for dual ported drives
    8. SFF_8087 -> SFF-8643 - not sure if these come in sideband/non-sideband variants
    9. SFF-8087 -> SFF-8088 internal to external adapter

    Do SFF-8087 -> SFF-8087 cables without sideband cause compatibility problems with expanders and or backplanes, and for wrapped cables which do not obviously have ribbon cable in them for the sideband, is there any easy way to tell if they have sideband lanes included?

    Is there any kind of crossover (or straight through if most are crossover already, which might be implied by SATA connectors needing to be forward or reverse) SFF-8087 -> SFF_8087 cable?

    Are SFF-8087 connectors inherently just flakey or do they need cleaning with alcohol? The metal shield the cable locks into is certainly super-flimsy and easily bent if not properly packed for shipment.

    Are there multiple levels of spec for SFF-8087 cables for SAS, SAS2, and SAS3 which would cause compatibility or detection problems? (I see that the new HP SAS expander model is using SFF-8087 for it's connectors instead of SFF-8643)

    Are some models of expander / controller / backplane especially picky about cable quality?

    Any other ideas and experiences / solutions?

    Last edited: May 28, 2015
    T_Minus likes this.
  2. neo

    neo Well-Known Member

    Mar 18, 2015
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    What brand cables are you using?

    I have learned my lessons over the years and only use Amphenol.
  3. sfbayzfs

    sfbayzfs Active Member

    May 6, 2015
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    I have generally been using OEM cables that come with things - Intel, Dell, HP, Supermicro, plus some cables of unknown origin. I will go back and re-test cables as I have time, but I remember at least once specifically when some of the brand new cables that came with an Intel RES2SV240 worked in a particular situation and others did not. (I can't remember if it was the short ones or the long ones which didn't work, but they are supposed to be the same, just different lengths.) My Supermicro branded cables very obviously have the sideband wires in them, but I have not tried them with the finicky controller/expander combinations yet.

    Perhaps the problems I am seeing are related to very slightly bent SFF-8087 connectors on a board causing poor contact between the cable and board.

    Does anyone else have any situations where anything was finicky about SFF-8087 cables or required the sideband connection?

    Generally, even though there are 4 SAS channels per cable, it seems that a cable either completely works or completely does not work in a particular situation. I would expect that if say some of the connections for one SAS channel were flakey, the controller and backplane or expander would negotiate to only use the 3 good channels, or report errors or something.

    Likewise, does anyone know of any good SAS debugging utilities in Linux or FreeBSD I could use to ask the controllers if they are talking to their expanders and or backplanes?
  4. canta

    canta Well-Known Member

    Nov 26, 2014
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    on linux world:
    for debuging on LSI, I am using MegaCli64, you can list connected expanders in detail
    sg tools.mostly using sg_ses. please take a look on The sg_ses utility and smp_utils package
    smp_utils package <- on how to find expander...

    for adaptec, arcconf will do as MegaCli does.

    Note: I Only have experience with Adaptec and LSi, :D. do no know with others.
    Oon other side, sg tools always a quick live-saving to check expander status including errors (as long as adheres to standard ses2)
    Last edited: Jun 2, 2015
    sfbayzfs likes this.
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