I see that you have ssh into the device which is good because you can now do the following
The last two is a major cause of lockups after plugging in a USB device. Believe me, I’ve done this at least four times with 3 lock ups and stopping the last two services clears up the plug ups entirely.
Now do the USB copy test. You should get about a max of 40MB/s to and from the USB and. If the USB device is not a WD drive, then you will get about 18MB/s write and 25 MB/s reads. No idea why the discrepency.
My best guess for the 40MB/s max is that is the max speed of writing through the gigabit ehternet for the Cloud. You should get 40MB/s writes through the gigabit ethernet to the USB 3.0 device.
Now in order to remove the usb device using the WEB/ui you have to restart the last two services.
Actually once you have stopped those services you should be able to restart them and leave them on anytime, but for safety reasons I leave them stopped.
What do they do? my best guess for the wdnotifierd is a service between the WEB/UI and any services that needs to put feedback to the WEB/ui. and wddispatcherd is probably something similar but dispatches a services. This is the reason that you may need to start them up in order to get the USB connected menu with the eject button.