ARCHIVED: In the Mac OS X Disk Utility, what is the First Aid function, and when and how should I use it?
Within the Disk Utility program, First Aid is a function for checking and repairing file system errors.
On this page:
When to use First Aid
If your computer is crashing frequently, displaying cryptic error messages, or exhibiting unusual behavior, you can use First Aid as a first step to check for defects and, in many cases, repair them. If, however, your volume has suffered severe corruption, you may need to use other utility programs or repair methods.
Even if you are not getting errors, it is a good idea to run First Aid periodically. This preventive maintenance can help keep small problems from developing into bigger ones.
Using First Aid
Note: For help with correcting permissions problems rather than file system errors, see ARCHIVED: Using Mac OS X, how do I repair permissions, and what does that do?
To check your startup disk, run First Aid from your software installation DVD:
- Insert the DVD, and then restart your computer. To force your
computer to boot from the DVD, hold down the
- Follow the instructions on the screen, and when the menu bar
appears, from the
Utilities(Mac OS X 10.5 and later) or
Disk Utilities(Mac OS X 10.4) menu, select
- In the column on the left, select the volume you want to repair,
and then on the right, click the
First Aidtab. You can select multiple volumes by holding down the
Commandkey while clicking the volumes.
- To begin a verification process (a simple check for errors), click
Verify Disk. To verify and repair any problems on the selected volume(s), click
Repair Disk. You can stop the scan at any time by clicking
The results of a verification and/or repair will be posted in the
window. Run First Aid repeatedly until you see the
following message at the end of the scan, where
is the name of your disk:
The volume "diskname" appears to be OK.
Note: Some volumes can be verified but not repaired (e.g., the startup disk, the volume where Disk Utility resides, a write-protected disk such as a DVD-ROM, or a disk that has open files). First Aid will warn you if one of these conditions exists when you select a volume.
Handling problems First Aid cannot repair
Occasionally, at the end of a scan, a message similar to the following will appear:
"Scan complete. Problems were found, but Disk First Aid cannot repair them."
This indicates that some of your files may be more severely damaged. To repair this damage, you can either back up your disk and reformat, or obtain a more comprehensive disk repair program. Two such programs are DiskWarrior from Alsoft, and TechTool Pro from Micromat Computer Systems.
Last modified on December 05, 2012.