How to repair a disk on a Mac with Disk Utility First Aid

2 min read · 7 steps · Updated 2 October 2026

Short answer

Open Disk Utility, choose View, Show All Devices, and select the last volume shown under the disk. Click First Aid and Run. Then do the same for each item above it: volumes first, then containers, then the disk itself. For the startup disk, do this from macOS Recovery.

First Aid checks the structure of a disk and repairs errors in it. It is the right tool when a Mac starts slowly or not at all, when files will not open, or when an external drive behaves oddly. It does not delete your data, but Apple still advises a backup first.

Menu names are from recent versions of macOS, where the settings app is called System Settings.

Step by step

  1. Back up if you can

    A disk that already has errors can fail completely. If the Mac still runs, make a backup before the repair: how to back up a Mac with Time Machine.

  2. Open Disk Utility

    It is in Applications, Utilities. To repair the startup disk, or if the Mac does not start, open it from macOS Recovery: on Apple silicon hold the power button until the startup options appear and click Options. On an Intel Mac hold Command + R while it starts.

  3. Show all devices

    Choose View, Show All Devices. The sidebar now shows each disk with its containers and volumes indented below it.

  4. Start with the last volume

    Select the last volume listed under the disk, click First Aid and then Run. Enter your administrator password if asked.

  5. Work upwards

    When it is finished, select the item above it and run First Aid again. Go on in this order: all volumes, then each container, then the disk itself at the top. If the First Aid button is dimmed for an item, skip it.

  6. Read the result

    A green tick means the item is fine or was repaired. If Disk Utility reports errors it cannot repair, the disk has to be erased and restored from a backup, or replaced.

  7. Restart

    Quit Disk Utility and choose Restart from the Apple menu.

Good to know

While First Aid checks the startup volume, the Mac may stop responding for a few minutes. That is expected.

If the disk does not appear in Disk Utility at all, shut the Mac down, unplug all devices that are not needed, check the cable and power of an external drive, and try again.

A drive with repeated errors is on its way out. Copy your data off it and stop relying on it.

Related: external drive not showing up on a Mac: 8 fixes to try and Mac starts up to a black screen: 5 fixes to try.

In short: Back up, Disk Utility, View, Show All Devices, First Aid on the last volume, then upwards through volumes, containers and the disk, restart.

Sources
  • Apple Support: How to repair a Mac storage device with Disk Utility

Rules and prices change. Check the official source before you act.