USB drive not working when switching from wifi to wired

Help and Support Raspberry Pi
1

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?

Paul

2

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?

3

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!