My raspberry pi is unable to detect my external hard drive, I'm wondering if I might have messed up in my setup.

The hub is connected to the pi in two ways: from the hub to the pi's microusb to give it power and from the pi to the source of the hub so I can connect stuff in the hub. The hub is powered, obviously.

The disk is an external hard drive, powered by usb. It does not have its own power supply. When I connect my disk in the hub, nothing happens. The disk does not start spinning. (It does when I plug it in my laptop).

When I ls /dev/sd* it does not find the disk.

I'm wondering if this configuration is messed up or if my usb hub does not have enough power for the hard drive or if the external hard drive must have its own power supply (cannot take it from the hub).

  • Variants of this question are quite common. You can search them. Have you measured the voltage on the Pi (between the TP)?
    – Milliways
    Feb 25, 2014 at 5:49
  • If there is no sound coming from the HD the problem is not the PI is the setup for powering the HD.
    – javirs
    Feb 25, 2014 at 7:36
  • What power rating is the hub in Amps? - hard drives need to draw alot of power...
    – Wilf
    Feb 25, 2014 at 13:14
  • The hub can output at 5V and 2A. I couldn't find how much power my hard drive needs.
    – SBSTP
    Feb 25, 2014 at 15:46

1 Answer 1


Step one, power the pi from a separate power source.

Step two plug the hub into the mains and then the HDD into the hub.

Step three if the HDD is now operational (making some noise leds on etc) then plug it into the Pi.

Step four run


on the Pi and there should be some output related to the disk being found and assigned a /dev/ point.

  • im still not seeing the hd, does it matter that its usb3.0 ?
    – Erik
    Jul 18, 2015 at 19:05
  • There are number of notes around the internet that the Pi has problems with USB 3 but they all seem to be anecdotal. That said I did find this forum.osmc.tv/showthread.php?tid=16818 which suggest you add max_usb_current=1 to your config.txt. Let us know how you get on.
    – rob
    Jul 20, 2015 at 13:52

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