• Re: Anyone able to advise on SAS hard discs and SAS controllers in a do

    From Theo@21:1/5 to i.love@spam.com on Thu Aug 18 09:53:55 2022
    [excessive crosspost removed]

    In uk.comp.homebuilt SH <i.love@spam.com> wrote:
    So can I get away with SAS breakout cables like these in order to use my exisiting case and Adaptec 7805 cards with SAS drives or am I
    overlooking something?

    IANA SAS expert but I don't see why not. SATA uses one 6Gbps lane per
    drive. SAS can use one or two lanes to reach 12Gbps - the gap between the
    SATA and power pins has some extra pins where the second lane comes in. A cable may only wire the SATA lane, so you only get 6Gbps, but that's ok as
    the drive will still work and probably the extra speed is marginal anyway.

    (there are reports of SAS drives not being recognised consistently where
    an alternative method is used to a SAS backplane)

    There are some extra pins for LEDs, detecting drive presence etc - sometimes vendor specific, but often using the SGPIO standard. Maybe the controller
    is looking for that, although I'd have thought you could turn it off? (sometimes backplanes have a secondary cable for GPIO)

    SAS drives are not SATA drives - some drives can do both, but I don't think all. If you plug them into a SATA controller they may not work.

    Otherwise I will have to invest in a enterprise grade server case to
    support SAS drives properly.

    Also worth looking for backplane parts out of old servers on ebay, which are cheap when the servers are scrapped. Sometimes they have proprietary connectors but others have standard ones, eg searching 'backplane sas':

    (you'd need to work out the power connector pinout to find out how to power it)

    Some of those have standard backplane connectors that you can get cables for
    - full list here:

    Those boards *should* operate without the SGPIO, fans or other stuff
    connected, but you'd need to confirm.


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