External USB Hard Drive Not Mounting in Sierra

Huntn

macrumors demi-god
Original poster
May 5, 2008
18,863
19,933
The Misty Mountains
Frequently when I call it a night, I unmount my external USB drive, turn it off and put my MBP to sleep. Frequently I find that my USB hard drive when turned back on does not mount and sometimes I can see it in Disk Utility and sometimes not. When I can see it if I select the drive and hit the "mount" button, nothing happens. Of note this drive has 2 partitions.

Is this a known issue?
What is the solution? Thanks!
 

Taz Mangus

macrumors 68040
Mar 10, 2011
3,627
475
Is this on the 2017 MBP? It could be the drive enclosure. I suggest that you try different USB C ports and see if they all act the same. As a sanity check, try out a different drive enclosure on the computer and see if it acts the same. When all else fails, a call to AppleCare might be in order.
 

Huntn

macrumors demi-god
Original poster
May 5, 2008
18,863
19,933
The Misty Mountains
Is this on the 2017 MBP? It could be the drive enclosure. I suggest that you try different USB C ports and see if they all act the same. As a sanity check, try out a different drive enclosure on the computer and see if it acts the same. When all else fails, a call to AppleCare might be in order.
Oct 2016 MBP. Thanks.
 

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