External Drive ejecting

[drmajor]

I have several External Drive docking units. Been fine for long time. Now, they seem to eject on their own and I get pop-up on Imac that drive was ejected improperly.

I can unplug or turn off/on and it will work for a while.

I have switched hard drives from one dock to the other with the issue staying with the dock.

Docks are USpeed 6618 & ANKER 6618 USB-2. Both run thru a USB powered hub.

What could cause the random ejection?

Suggestions?

 

[DeltaMac]

"USB powered hub"?
Do you mean a bus-powered hub (no power connection, just USB), or self-powered (has its own power cable or a "wall-wart)?
Does one dock seem to have more problems than the other?
Can you try connecting one of the docks directly to your iMac, leave the other connected to the hub, then use it like that for a few days. Maybe that will make a difference that will help you sort out if you have a problem with just one of the docks, or the USB hub could be less than reliable.
There could even be macOS software issues with USB. Which version of macOS are you running now?

 

[drmajor]

USB is powered via wall power.
Running El Capitan 10.11.6

Will try running directly off Imac

 

[Fishrrman]

This question may seem unusual, but…
… how many PORTS does your USB hub have?

 

[kagharaht]

USB is powered via wall power.
Running El Capitan 10.11.6

Will try running directly off Imac

This happens randomly for me. All externals have their own power supply. USB Hubs are powered and the power draw are well within the 500ma for each devices. Yet once in awhile maybe once every couple of weeks or so, one just randomly ejects itself. There is no rhyme or reason. Even the ones that I plug directly to the iMac to see if that prevents it, eventually randomly ejects itself. This is an iMac 14,1 - i5 Late 2013, which I bought in 2015 new. It happened more often in El Capitan. Less so with Sierra.

 

[drmajor]

USB is powered via wall power.
Running El Capitan 10.11.6

Will try running directly off Imac

8 ports

 

[drmajor]

Ports = 8
Tried running straight off Imac- no hub. same.

 

[t0mat0]

Dips in power can do it - they can trip drives as well as electronics like cookers, microwaves etc. The electric company could check by placing a device in your house if needed. It if it's regular maybe look at a UPS?