Here is a situation:

  • iMac 5K from 2014 with Fusion drive, fusion drive is formatted as APFS, volume is called DATA and there is nothing on it.

  • Firmware password is set.

  • External USB drive (SSD) is connected, formatted as APFS and has Mojave on it. Drive is also encrypted with Filevault.

  • SSD is selected in System Preferences as the startup disk.

When I turn on the computer, it works fine, boots from USB drive.

When I then press Restart... from Mojave, the iMac restarts and shows me a blinking folder icon with a question mark.

I can press the power button for 3 seconds to turn the iMac off, and when I turn it back on it boots fine.

Can I do anything to make it reboot as well?

I attach screenshots from Disk Utility. enter image description here enter image description here


  • 1
    The Fusion Drive doesn't appear to be formatted as APFS container/volume but Core Storage and HFS+. – klanomath Nov 14 '19 at 15:50
  • I don't think you can set an external disk is a default boot device natively. rEFInd may be able to help you; install it to the EFI System Partition that ought to have been silently created on your Fusion Drive when it was created in Disk Utility. To check if such partition exists, use diskutil list when booted into macOS. Edit your question and add the output if you'd like assistance proceeding. – Jivan Pal Nov 16 '19 at 19:44

You must log in to answer this question.

Browse other questions tagged .