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I'm still trying to workaround to attach multiple 3.5 HDDs on my Raspberry Pi 4B without a centralised hub. Everytime my Raspi Boots, or boots up the drives, it does so with booting all of them at once.

This causes a power problem, because the spinning up of the mechanical drives draws too much power and the Pi is stuck in an infinite boot loop.

Any ideas, boys?

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  • You could create a background script that mounted the first drive waited then mounted the second, but this is a kludge. Feb 20, 2021 at 14:05
  • There are ways to control power to usb ports. look into uhubctl. In addition to controlling the hub built into the pi, some external hubs support this too.
    – Abel
    Feb 20, 2021 at 14:47
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    I'm gonna agree and disagree with @SteveRobillard in that I think using a script here is not a kludge -- ideally there would (and might) be a systemd feature to tweak this, but it would probably take less time to write the script than to dig around for that. You then want them in /etc/fstab with noauto. I'll post an example later...
    – goldilocks
    Feb 20, 2021 at 14:54
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    The problem, though, may well be that it's nothing to do with mounting and just the power coming on and something that can't be controlled by the pi (although what @Abel mentions could turn them off again quickly). You could test this by using noauto in fstab without a script to mount them (so they end up not being mounted).
    – goldilocks
    Feb 20, 2021 at 14:56
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    @goldilocks I consider it a kludge because while it may work, it does not do so by solving the root cause of the problem (which is likely a power issue). Feb 21, 2021 at 0:52

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Turn the drives on first, then they will have power going with them already running. That is what I do with my single spinner and the SSD attached to it. Good luck with it the USB is so flaky on these things. If I am stupid enough to leave the keyboard attached I get a no boot in this configuration with my Pi 4. If trying to do this drawing the power from the Pi it will never work, you can only get 1.2A power drawn from the ports combined for all 4 USB ports. If you do not know 1.2A x 5V = 6 Watts of total power it can supply.

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  • You might want to mention the possibility of using a powered hub instead of powering all from the RPi's USB ports.
    – Seamus
    Feb 21, 2021 at 1:32
  • He had mentioned in his posting before whoever edited it, he wanted to avoid a powered hub now it says centralized for some reason, whoever thought this was a better wording for it is beyond me.
    – user130167
    Feb 21, 2021 at 2:05
  • Ah - yeah - I see that now. So your answer then is to stagger the start times and thereby avoid the inrush current of multiple disks starting at once?
    – Seamus
    Feb 21, 2021 at 2:23
  • Have them on at the start of the machine, then the surge to spin up current draw is gone, yes. Turning them on afterwards does no good the spin up still happens then. Looking at old 500gb drive here it is 5v @ .345A simply running for well over quarter of the 1.2A it can do who knows how much during the spin up.
    – user130167
    Feb 21, 2021 at 2:34

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