When you try ejecting a single volume of a bootable volume group on an external disk, other volumes are also ejected even though you chose to keep them mounted.
eject
Finder refuses to eject a volume because it’s in use, or Disk Utility complains that it can’t unmount a volume. Here’s what to do about it.
Why do I keep getting alerts that my three external drives are not ejected properly?
Whenever I try to eject removable storage media, I am warned that an application might still be using them. Why?
My two USB drives have started to eject themselves, suddenly and without any warning. Why?