Step 2 (now that you are booted on a the USB stick and not the main HD):

When it’s done, insert your USB drive into any Mac, then launch the installer by holding down the Option key.

Select your flash drive from the drop-down menu.

This is should be located in your Applications folder.

Open Disc Creator and click the “Select the OS X Installer” button.

If you have any other data on that flash drive, back it up now, because the installer will delete everything on it.

Insert an 8GB (or larger) flash drive.Download the macOS Sierra installer and Disk Creator.The easiest way to create a USB flash installer is with the free program, Disk Creator. You need to create a USB flash installer, then reformate the drive then reinstall. What the issue is, you are trying to modify the drive you are currently working on which it doesn't like. In its place would be 'disk0s2.' It is this indented entry that you want to erase.I'm writing this as I search for it and found solutions and none of them worked and I noticed I wasn't the only one.Įasy solution is hold down command + R and get into disk utility, select the main HD and select File > 'Enable journaling' but if you are like me, it was greyed out. You might see that it is displayed on the list as:

To be sure you do this right, please observe that the drive may appear in the list as ghosted because it is unmounted. Use the device reference in this next command. It will appear similar but not the same as this: /dev/disk0s2. In the output, you should find your Fusion drive listed. At the prompt paste these lines individually pressing RETURN at the end of each line. If that doesn't work then quit Disk Utility and open Terminal from the Utilities' menu. After doing that click on the Unmount button in the toolbar to see if the disk disappears from the Desktop. Try repairing the disk in Disk Utility using First Aid.

Could not unmount disk osx