Using Disk Utility and First Aid on your Mac

Disk Utility is the program on your Mac for viewing, checking, repairing and erasing drives. The most important function when there are problems is First Aid: it checks the drive for errors and repairs them where possible. This article explains how to use Disk Utility and First Aid, also when your Mac no longer starts properly, and what the result means.

Blue Apple repairs MacBooks in Amsterdam. First Aid fixes many software errors, but not a broken drive; more about that at the end.

Opening Disk Utility

• Normally: via Spotlight (Command + Space bar, type "disk utility") or in Applications, Utilities.
• If your Mac does not start properly: in Recovery mode. See opening Recovery mode.

In the View menu choose Show All Devices, so you see not only the volumes but also the drives themselves.

Running First Aid

1. Select the volume you want to check in the sidebar, for example Macintosh HD.
2. Click First Aid at the top and then Run.
3. Wait until it finishes. While checking the startup disk your Mac may not respond for a moment.
4. Repeat for the other volumes and then for the drive itself (the top level).

The result

• "Operation successful" without errors: the drive structure is fine.
• Errors found and repaired: restart the Mac and see whether the problem is gone.
• Errors that cannot be repaired: back up what you can still reach as soon as possible. The drive may be damaged.

Other functions

• Erase: empty and format a drive or volume. Note: everything is lost. See formatting a drive.
• Mount and Unmount: make a drive appear or disconnect it. See external drive not showing.
• Partition: split a drive into parts. On modern Macs rather use extra APFS volumes (with the plus), which share the space.
• Info: see how much space is free, and the format and type of the drive.

Volumes, containers and drives: what is the difference?

In the sidebar you see different levels. The top one is the physical drive, for example the internal SSD. Below it, on modern Macs, sits a container, and in it the volumes, such as Macintosh HD and Macintosh HD - Data. Your files are on the Data volume, macOS on the system volume. So run First Aid on all levels, from bottom to top. An external drive usually has only one volume.

When do you use First Aid?

• Apps do not open or freeze, and a restart does not help.
• Files are damaged or disappear.
• Your Mac starts slowly or hangs on the Apple logo.
• An external drive behaves strangely.

When First Aid is not enough

First Aid repairs the drive's structure, not the drive itself. If Disk Utility no longer sees the internal drive at all, First Aid cannot repair the errors, or they keep coming back, there is probably something with the hardware: an SSD that is failing or a problem on the logic board. Then back up straight away. See backing up.

What we do at Blue Apple in Amsterdam

We test your MacBook's storage and logic board, and check what can still be saved of your data if the drive is failing. You hear beforehand what is possible and what it costs. More on our pages about MacBook data recovery and MacBook repair in Amsterdam.

Frequently asked questions

Does First Aid erase my files?

No, First Aid only checks and repairs. Erasing only happens with Erase.

How often should I run First Aid?

Only when there are problems. It is not maintenance you need to do regularly.

What does "Container disk" in the list mean?

That is the APFS container your volumes sit in. On most Macs you do not need to do anything with it.