External drives · Setting up your drive
What do "looks good", "usable with warnings" and "not suitable" mean in Choose Drive?
Short answer: Looks good means a Mac-formatted external drive. Usable with warnings means it works but isn't ideal (for example exFAT) and you confirm with Use Anyway. Not suitable — internal, network or FAT32 drives — can't be selected.
They're the compatibility verdict for the selected drive, with the specific reasons listed underneath.
- Looks good (green) — a Mac-formatted (APFS or Mac OS Extended) external drive.
- Usable with warnings (orange) — it will work, but something isn't ideal, such as exFAT or another non-Mac format. You can still use it; the confirmation calls the warnings out and asks you to Use Anyway.
- Not suitable (red) — internal drives, network drives and older Windows formats such as FAT32. Use This Drive stays disabled.
The speed test adds its own verdict: a drive that's too slow is blocked, a slow one gets a warning.