I recently bought a MyBook Duo 16TB for my iMac (27" mid-2011 series), running macOS Sierra 10.12.6. Just FYI, this iMac has USB 2.0 ports, not USB 3.0.
I successfully reformatted the disk and used the WD utilities to change it to a RAID 1 disk with 8TB of storage.
Unfortunately, once this was ready, but before I copied any data onto the disk, I noticed that the disk was disconnecting then reconnecting itself without my removing the cable. I got the message about “Eject before removing”, then the disk would reconnect, then I’d get the warning again, and so on. I disconnected the drive and unplugged it and then waited a few days (I had other things to do).
Now, when I connect the external drive to my iMac, I cannot see it in either the Finder, Disk Utilities, or the WD Drive Utilities apps. This is despite the drive white line lighting up and me being able to hear the drive’s fans.
When I connect the drive to my MacBook, however, the drive appears to work fine, so I suspect that both the cable and drive are OK.
On the other hand, I was able to set the drive up without any issues on my iMac, which is the primary machine that I want to use the external drive with.
Can anyone suggest something that may help me make the drive work again?