Hmmm.... I don't know if this is specific to just this drive, or this sequence of events, but...
I have an external drive constantly tethered to my laptop. Due to the quick where you get an "Unexpectedly disconnected" error if you sleep the computer with a USB drive (at least I always do get it!), I eject the drive manually before sleeping the computer, then unplug it, and when I wake the computer up I plug the drive back in.
{rabbit trail} I REALLY WISH that power management worked right, but no matter what I do the system keeps waking up while sleeping. I turned off every thing I could find that was mentioned on the net, but still I get random wake events, mostly from RTC (Alarm), when I don't have anything set to wake the computer. I think this is related to the "unexpected disconnect", because I think the system wakes up in low power mode, doesn't properly init the drive and/or unmount it when it re-sleeps, thus the error{sigh}
Since B3, the drive never re-mounts. In fact, the drive motor engages but the LED never comes on. Even after numerous unplug/replug attempts. A reboot puts things right again until I sleep the computer. I have looked through the system logs but can't find anything that hints at the problem. 😟
It would be great if this were any indication Apple was working on the whole "unexpectedly disconnected" problem, {sarcasm on} but I doubt they care because, after all, you are supposed to use the cloud now and not need any external drives. {sarcasm off}
