Disk Utility User Guide
Disk Utility can fix certain disk problems—for example, multiple apps quit unexpectedly, a file is corrupted, an external device doesn’t work properly, or your computer won’t start up. Disk Utility can’t detect or repair all problems that a disk may have.
If you run First Aid on a disk, Disk Utility checks the partition maps on the disk and performs some additional checks, and then checks each volume. If you run First Aid on a volume, Disk Utility verifies all the contents of that volume only.
Partition a physical disk in Disk Utility on Mac. Partitioning a disk divides it into individual sections, each of which acts as a separate volume. However, with APFS, you shouldn’t partition your disk in most cases. Instead, create multiple APFS volumes within a single partition. Download Bootdisk Utility - Create bootable USB disks with your favorite MAC OSX distribution and latest Clover bootloader by turning to this lightweight application.
In the Disk Utility app on your Mac, choose View > Show All Devices.
Note: If you’re checking your startup disk or startup volume, restart your computer in macOS Recovery, select Disk Utility in the macOS Utilities window, then click Continue. If you check your startup volume (Macintosh HD), make sure you also check your data volume (Macintosh HD - Data).
In the sidebar, select a disk or volume, then click the First Aid button .
If Disk Utility tells you the disk is about to fail, back up your data and replace the disk—you can’t repair it. Otherwise, continue to the next step.
Click Run, then click Continue.
If Disk Utility reports that the disk appears to be OK or has been repaired, you’re done. You can click Show Details to see more information about the repairs. Otherwise, you may need to do one of the following.
If Disk Utility reports “overlapped extent allocation” errors, two or more files occupy the same space on your disk, and at least one of them is likely to be corrupted. You need to check each file in the list of affected files. Most of the files in the list have aliases in a DamagedFiles folder at the top level of your disk.
If you can replace a file or re-create it, delete it.
If it contains information you need, open it and examine its data to make sure it hasn’t been corrupted.
If Disk Utility can’t repair your disk, or you receive a report that the First Aid process failed, try to repair the disk or partition again. If that doesn’t work, back up as much of your data as possible, reformat the disk, reinstall macOS, then restore your backed-up data.
If your Mac has a Fusion Drive and you see a flashing question mark or alert, see the troubleshooting section of the Apple Support article About Fusion Drive, a storage option for some Mac computers.
If you continue to have problems with your disk or it can’t be repaired, it may be physically damaged and need to be replaced. For information about servicing your Mac, see Find out how to service or repair your Mac.
Let macOS manage space between multiple volumes
With Apple File System (APFS), the file system introduced in macOS 10.13, you can easily add and delete volumes on your storage devices. APFS-formatted volumes automatically grow and shrink—you never have to repartition a storage device again.
Keep your external storage devices secure
When you get a new flash drive or other storage device, format it as APFS and encrypt it with a password to protect its contents.
Download Disc Utility For Mac
Give your disk a checkup
If you’re having problems with a disk, Disk Utility can check the disk and repair problems it detects.
Download Disk Utility Mac Os X 10.6.8
To browse the Disk Utility User Guide, click Table of Contents at the top of the page.
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