USB drive not working when switching from wifi to wired

I have a Pi with an un-powered WD ‘Elements’ drive attached, the Pi being connected to a USB hub with a wireless connection. Everything works fine - I can access the drive via sftp and samba from my desktop on the LAN and via my phone.

I’ve just moved the Pi to another room so I can connect using a cable rather than over wireless. When I plug in the ethernet cable and unplug the hub (which has nothing else attached other than the wifi dongle) I can no longer access the Elements drive and it makes a clicking sound. I found this thread: Portable Hard Drive - Mounting which attributes a clicking drive to a lack of power but I’m not changing anything related to power.

Just to check, I left the usb hub plugged in to the Pi but removed the wireless dongle from it but with the same results. I have the latest version of OSMC installed and I’m using the original power supply (and haven’t changed the clock speed).

Any suggestions please?


It’s entirely possible that the USB hub was providing some “back power” to the Pi. This is not unheard of and has been seen a number of times.

Have you enabled max_usb_current=1 in config.txt?

Thanks ActionA, that fixed it.

I had read that in the thread I mentioned but it wouldn’t work if I left the usb hub connected to the Pi and just removed the wireless dongle. I still don’t understand why. Maybe if the hub is empty it doesn’t provide any back power…?

Either way max_usb_current=1 does the trick!