External drives · Ejecting and reconnecting
What happens if I unplug the fast drive without ejecting it?
Short answer: Usually nothing is lost: a move only removes the original after the copy is verified, and interrupted work pauses and resumes when the drive returns. macOS will warn about an improper eject — use Eject fast drive next time.
Usually nothing is lost, but it's worth avoiding. macOS shows its Disk Not Ejected Properly warning, and any file being written at that moment may not be complete.
Storage Studio is built for this: a move only removes the original after the copy on the drive has been verified, so a move cut short leaves your original in place. Transfers and moves that were waiting pause and pick up again when the drive is back, and the drive-to-drive Transfer and Backup copies resume automatically.
Plug the drive back in, let macOS check it, and look at Background Activity if anything reports a problem. Next time, use Eject fast drive first.