External drive does not mount after plug off without eject

I accidentally unplugged my hard drive without properly ejecting it, and now the drive does not mount when plugged in.

What can I do to make it work again?

I can see the disk in lsusb and diskutil list.

So far, I've tried:

• sudo diskutil unmountDisk force /dev/disk2
• sudo diskutil unmount force /dev/disk2
• Reboot with disk.
• Reboot without disk.

It seems that the disk is working because it's vibrating very slowly, but I can't see it in Finder.

Solution 1:

SOLVED. Had this problem today. OLD external drive, had its own power source, plugged into a surge protector. I hit the power button on the surge protector when I was unplugging something else, and the drive was turned off while in use. I turned it back on and it sounded normal, but my computer wasn't recognizing it, and Disk Utility wouldn't load when it was plugged in. I tried restarting with and without the disk, mounting, unmounting, all of the above recommendations.

"unmount" led to "the disk is already unmounted or has a partitioning scheme...."

"mount" and "eject" said the attempt timed out.

"mountDisk" said it was successfully mounted, but I still couldn't access it, and "unmountDisk" would be successful as well, but no luck to "mount" or "mountDisk" afterwards.

I finally found the order that worked.

diskutil unmountDisk /dev/disk2
diskutil eject /dev/disk2

then I just plugged it back in to my computer and we were golden. Thanks for all your help everyone.

Solution 2:

I'd recommend checking if fsck is holding your disk hostage upon connection. This was it for me.

Running ps aux | grep fsck revealed:

root              2587   7.3  0.1  4363584  21780   ??  U    10:56PM   2:22.54 /System/Library/Filesystems/exfat.fs/Contents/Resources/./fsck_exfat -y /dev/rdisk2s1

So the solution was a sudo kill -9 2587 (insert your PID instead of 2587) (or sudo pkill -f fsck). As soon as that ran, my Volume immediately mounted.

Oh the irony of fsck being the problem...

Addendum (from a related question/answer): Ideally, you're better off letting fsck run its course. Otherwise, you'll run into this the next time too.