I'm not sure when this started, maybe when I setup my Time Machine partition to be encrypted or maybe at a particular OS update, but the Time Machine drive no longer ejects properly. I'd love some help on this one!

Here's what happens:

  • I have an external drive with two partitions: an encrypted partition for Time Machine, and another AFPS (Encrypted) one called "Extras". The drive plugs directly into my MacBook Pro 2015 15" running macOS 10.14.4

  • On a fresh restart with the drive plugged into a USB port, the two partitions appear normally in both Finder and Disk Utility. Time Machine works and everything is good.

  • If I eject the drive (either from Finder or Disk Utility), it appears to eject normally (disappearing from Finder, greying out in Disk Utility) until I actually pull the USB cable out of the MacBook. Instead of the greyed-out drive disappearing altogether from Disk Utility, nothing changes.

  • If I plug the drive back in, then the Extras drive appears again in Finder but Time Machine does not. In Disk Utility, it looks a little weird (see below): a second drive appears with the same name (but nothing under it), and the Extras drive appears under the initial drive.

After plugging hard drive back in:

enter image description here

I've tried various combinations of unmount/unmountDisk/eject with the diskutil command, and once in a while a command sequence does work… but it's never repeatable. Now I just have to restart the computer whenever I want to access Time Machine again.

Any ideas here? Thanks for reading.


I think that the main reason is that your Time Machine is making a backup at the moment you are trying to eject the drive. That is why you sometimes succeed (TM already finished the job) to unmount it and other times not.

This link may also help you. It describes the solution of a similar problem.

Before you try anything from below, I highly recommend you to check your Time Machine and make sure that it is not trying to make a backup while you are trying to unmount the drive.

The solution from link:

The way to diagnose if your issue is the same - go to System Information utility, and see if your drive is showing up under USB section. Mine was there, so it was clear that it's not the issue with the drive itself.

The thing is - when it is trying to get mounted, OSX is launching a process "fsck_hfs". It's the same process that appears when you're performing "first aid" on the disk, so the OSX is trying to check the disk before mounting it.

What I did - I force quit this process in Activity Monitor utility, then the disk appeared in Disk Utility, and I was able to perform First Aid on it manually.

After that Time Machine was refusing to use the disk and complained it was "read only", so I had to turn Time machine off, unmount the disk, restart, mount the disk and enable Time Machine again.

  • 1
    Please include the solution from the link into your answer. As it is, this is basically a link-only answer.
    – harrymc
    May 17 '19 at 13:15

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