Mellanox ConnectX-3 on ebay look strange

Discussion in 'Great Deals' started by Stefan75, Oct 21, 2019.

  1. hmartin

    hmartin Active Member

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    No, they said for that quantity, if you want the adapter, buy the auction with the Mellanox card and shuck the adapter yourself.

    The adapter is passive, so I don't think it would be beyond the realm of someone to design their own. The OCP mezzanine pinout is public, as is the PCIe pinout. I don't do PCB design but someone could probably OSH Park an adapter for less than the $22 this seller is charging for the adapter + Mellanox.

    I would definitely be down for 5 adapters, if anyone with PCB experience is looking for a commission ;)
     
    #21
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  2. JustinClift

    JustinClift Member

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    Looking at the adapter photo's by @matthew5025:

    https://forums.servethehome.com/index.php?attachments/image-sfp-jpg.12177/

    https://forums.servethehome.com/index.php?attachments/image-sfp-4-jpg.12180/

    ...some things stand out about the PCB design:
    • It has places allocated for resisters, but they appear to be unpopulated.
    • Not sure if it's just a two layer pcb (back and front) only. The traces + via's (the small round holes) seem to just be connecting both sides of the PCIe traces through to the OCP connector in fairly simple fashion.
    • If that's really the case, it should be reasonably straight forward to map those out, and make a new pcb.
    Not sure if it's useful, but I've been getting an old X-carve (hobby level CNC machine) up and running at a local Maker space. Got it responding to movements ok last week, and AFAIK the only thing it needs next is to be calibrated (not hard).

    That's pretty much the exact thing needed for doing initial PCB prototyping, prior to getting a batch made.

    Am kind of iffy on whether it's something I want to do though. It'd be my first PCB creating experience, so probably wouldn't be a bad intro... :)

    Hmmm, I'll ask the Makerspace people if anyone there has PCB creation experience. If they do, that'd be really useful. :)
     
    #22
  3. JustinClift

    JustinClift Member

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    #23
    Last edited: Nov 1, 2019
  4. Floggedhorse

    Floggedhorse New Member

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    #24
  5. int0x2e

    int0x2e Member

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    These are only 10G. There are other ConnectX-3 / CX3Pro based cards that support 40/56Gb. Strongly advise you read a little more before you spend your money (though these aren't too expensive).
     
    #25
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  6. JustinClift

    JustinClift Member

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    Yeah, it's one of those things that, if you're coming from a 1GbE background and haven't really used 10/40/etc Gb/s network gear before, you're definitely best off starting small and getting the hang of things. Infiniband is a substantially different stack compared to Ethernet / TCP/IP. Not all software even works with Infiniband, though there are workarounds (IPoIB) which can go pretty far on some OS's.

    If there's a general scenario you have in mind (eg you're wanting to set up XYZ network structure for project ABC), then maybe share the details of that and we can advise? :)
     
    #26
    Last edited: Nov 19, 2019
  7. Floggedhorse

    Floggedhorse New Member

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    Many many thanks.

    Will take your advise and start small, especially as I'm peer to peering between windows and Linux

    Many thanks .... my money survived the night

    Think I'll spend a tad more and purchase something more standard such as this way more availability of drivers and hopefully easier curve

    Again thank you
     
    #27
  8. JustinClift

    JustinClift Member

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    With those, notice that specific Ebay item comes with the short (half height) bracket. If you're thinking to put it in a standard ATX mini tower case or similar, although the card will fit, the bracket wont. ;)
     
    #28
  9. JustinClift

    JustinClift Member

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    As an additional thought, if you're just after a straight connection between two boxes (eg server to a workstation), then something like this would be fairly simple:

    Mellanox MCX311A-XCAT CX311A ConnectX-3 EN 10G Ethernet 10GbE SFP+ PCI-E NIC | eBay

    Note, I don't know that seller at all, etc. It's just the first example on Ebay showing a preselected bundle of two cards + matching cable.

    That's only a 10GbE setup, but depending on what your needs are, it could be fine. Going for something higher speed, like the cards you pointed to, would work too but be a bit more expensive again. Still not that expensive though. :)
     
    #29
  10. Mcdull

    Mcdull New Member

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    I've been watching this for a while, as I'm not sure $30 for a card is good price?
    It's not bundle of two cards, the picture is just to show low and high profile bracket.
    It said specifically purchase is for one card only in the description
     
    #30
  11. JustinClift

    JustinClift Member

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    Sorry, my bad. Sometimes people have bundles available of 2 x [some card] + 1 x [correct cable to join them]. Makes it easy for new people who just want a solution that works easily. Thought it was one of those.
     
    #31

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