To repair a disk on Mac, you can use the built-in tool called Disk Utility. It is ideally used when the external storage device is corrupted or does not work properly, when the computer does not boot or when you want to check the disk for problems. It can also be used for general maintenance or if you’re Mac has slowed down.
Disk Utility is a simple to use application, which can be of tremendous help both to identify and fix issues with drives.
- To launch Disk Utility, go to Finder, which is present in the dock
- Then click Applications > Utilities
- Click on Disk Utility, choose View > Show All devices
- Select the disk to repair on the list in the left and click on First Aid > Run
It may take a while for Disk Utility to run depending on the size of the drive. Once the process is complete, it will report the status of the selected drive.
- If it reports that the disk can’t be repaired, then you may have to replace the drive.
- If it finds any errors it can repair, it will repair it for you
- In other cases, you may encounter errors such as ‘Overlapped extent allocation’, where you will have to debug further to resolve the issue.
You can also use Disk Utility to repair problems with your Mac startup drive. But the steps are a little different. In that case, enter recovery mode by holding Command + R keys when your Mac is starting up. In the recovery menu, select Disk Utility and proceed with the steps as explained above.
When Disk Utility fails to resolve issues, you can use another built-in tool called FSCK, short for File System Consistency Check. It is a program to check and repair the file structure of the selected hard drive. To run FSCK, you are required to enter single user mode.
- Restart your Mac and hold Command + S keys when you hear the chime
- A command prompt opens
- Type ‘fsck –fy’ without the quotes
- Fsck checks the file system for errors and repairs any corruption/damage it finds. Once the fsck program is complete, you will be reported a status message.
- If Fsck reports, ‘The volume appears to be Ok’, the drive has been repaired
- If Fsck reports, ‘File system was modified’, run Fsck again until you see an Ok message
- Finally, type ‘reboot’ to restart the computer normally
Disk Utility and FSCK are wonderful programs to fix issues with your external hard drives, but if none of these methods work, it could be that your hard drive is dead or physically damaged. In such cases, it is best to recover data from it using tools such as Remo Recover and replace the drive. Read how to recover data from a dead hard drive if you want to learn more about the recovery process.