Mac Disk First Aid Software

  1. Mac Disk First Aid Software Free
  2. Disk First Aid Windows 10
Disk First Aid
Developer(s)Apple Inc.
Stable release
Operating systemClassic Mac OS
Typesoftware utility

Disk First Aid is a free software utility made by Apple Inc. that was bundled with all computers running the classic Mac OS.[1] This tool verifies and repairs a limited number of directory structure problems on any HFS or HFS Plushard disk or volume.[2]

Disk First Aid is a very simple tool, with it only being able to detect and repair directory damage[3] and many books are critical of its sometimes inaccurate reporting of errors, and often suggest to run the tool more than once to ensure you are receiving a consistent result.[3][4][5] Disk First Aid is located in Applications:Utilities:Disk First Aid.[4] The classic Mac OS provides an option to run Disk First Aid on startup, although it has been reported that it provides little gain and sometimes can amplify a problem.[4]

Right click the Macintosh HD in Disk Utility and select Mount button. Solution 2: Repair the Macintosh HD with First Aid. If the Macintosh HD fails to mount manually, you can also check and repair the Macintosh HD with First Aid. Step 1: Boot into macOS Recovery mode. Step 2: Select Disk Utility from macOS utilities and click Continue.

Its capabilities were incorporated into Disk Utility in macOS.

Situations to use the tool[edit]

One source suggests that disk utility should be used when there are:

  • Frequent system crashes
  • Disappearing files
  • Files changing size
  • Problems copying files from one place to another.
  • Problems saving files.
  • Cryptic error messages.[5]

as well as for general maintenance every 6 months.[6]


Disk First Aid has built-in capabilities to check for damage to:

  • Partition Map,
  • Device Driver,
  • Boot Blocks,
  • Master Directory Block,
  • Volume Bitmap,
  • Catalog File,
  • Extents File,
  • Finder Attributes,[4]
  • Disk volume,
  • Extent B-tree,
  • Catalog B-tree,
  • Catalog Hierarchy,
  • Volume Info,
  • and to search for locked volume name.[7]

After analyzing the disk directory, Disk First Aid determines whether it is able to repair any damage that was detected. The utility can commonly only fix problems associated with the catalog/extents files and the volume bitmap.[4] Commonly, the program reports that there is an error, but cannot fix it.[3]

See also[edit]


  1. ^ abWatson, Andrew (2008-02-07). 'Disk First Aid Utility in Mac'. Retrieved 2009-01-12.[permanent dead link]
  2. ^Stauffer, Todd (2004). How to Do Everything with Your iMac. McGraw-Hill Professional. p. 456. ISBN0-07-223188-2. Retrieved 2008-01-12.
  3. ^ abcBreen, Christopher (2002). Mac 911. Peachpit Press. pp. 104–5. ISBN0-201-77339-2. Retrieved 2008-01-12.
  4. ^ abcdeLandau, Ted (2000). Sad Macs, Bombs, and Other Disasters: And what to Do about Them. Peachpit Press. pp. 805–11. ISBN0-201-69963-X. Retrieved 2008-01-12.
  5. ^ ab'In OS X, what is First Aid, and when and how should I use it?'. University Information Technology Services Knowledge Base. Indiana University. 2008-12-18. Retrieved 2009-01-12.
  6. ^'Disk First Aid for Macintosh'. IT Service Desk (8help). Ohio State University. 1999-06-04. Archived from the original on 2009-03-17. Retrieved 2009-01-12.
  7. ^'Mac OS 9 - How to Use Disk First Aid'. Computing@UW-MADISON KnowledgeBase. University of Wisconsin-Madison. 2001-02-09. Retrieved 2009-01-12.
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Summary: First Aid process has failed on external hard drive? In this article, we will tell you what to do if First Aid can't repair external hard drives, SD cards, USB flash drives and more. If necessary, recover lost data from the external hard drive with iBoysoft Data Recovery for Mac to avoid permanent data loss.

Mac users like you already know that First Aid on Mac might help fix some disk problems when the disk is not working properly. However, it sometimes can fail to repair the disk. During the running of First Aid on an external hard drive, one of the following error messages may pop up indicating First Aid operation failure:

  • 'First Aid process has failed. If possible back up the data on this volume. Click Done to continue.'
  • 'First Aid could not unmount the volume for repair. Click Done to continue.'
  • 'First Aid found corruption that needs to be repaired. To repair the startup volume, run First Aid from Recovery. Click Done to continue.'

Note: Only when you are using the external hard drive as a startup disk and run First Aid to repair it, you could see the error message to ask you to run First Aid from macOS Recovery.

Don't worry. This post will help you solve the First Aid not working problem and recover lost data from the troubled external hard drive.

Table of contents
1. What does First Aid do in Disk Utility?
2. What to do if Disk Utility's First Aid has failed on external hard drives?
3. Conclusion

First of all, let's take quick look at what First Aid can do in Disk Utility.

What does First Aid do in Disk Utility?

First Aid in Apple's Disk Utility is a small utility designed to verify and fix minor problems of a drive, such as repairing the drive's data structures, fixing external hard drives not mounting on Mac, external hard drive not readable on Mac and so on. It has the capability to detect and repair the damages to partition map, master directory block, device driver and so on.

But why Disk Utility's First Aid would fail on external hard drives?

Most of the time, First Aid's failure on external hard drives is due to severe disk corruption which was brought about by improper ejection, physical damage, virus infection or other reasons.

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Mac Disk First Aid Software

In the next section, you will learn what to do if First Aid repairing process has failed on external hard drives.

What to do if Disk Utility's First Aid has failed on external hard drives?

Generally speaking, if you can't run First Aid on an external hard drive to repair it, the solutions left for you to repair the corrupted external hard drive on Mac are limited. We have concluded three methods for you to try one by one, hoping they can repair the corrupted external hard drive successfully without losing data.

Solution 1: Run First Aid one more time

On Apple's official Support page, users are encouraged to run First Aid more than once. First Aid will try to verify and fix the content on the selected volume every time. Therefore, there might be a hope that it works after you rerun it. If you are receiving a constant result saying the process has failed, you can move to the next solution.

Solution 2: Run FSCK command from Single User Mode

FSCK (File System Consistency Check) is Mac and Linux version of CHKDSK command in Windows. It can check the file system and try to repair the damages it finds. FSCK command can be run to repair a boot disk or a non-boot disk. Therefore, if running First Aid on Macintosh HD failed or Macintosh HD could not be repaired in Disk Utility, you can also run FSCK command to repair the startup disk.

However, unlike CHKDSK command in Windows, you can't run FSCK command inside the operating system. You need to exit the operating system and reboot into Single User Mode.

Tips: You won't be able to see this article when you are running FSCK command, so we recommend you write down the steps below especially the command lines for your convenience.

Follow the steps to fix the corrupted external hard drive using FSCK command:

Step 1: Go to Disk Utility, select the corrupted external hard drive, and remember the file system and Device name. In the picture below, the file system in Mac OS Extended (HFS) and Device name is disk3s2.

Step 2: Restart your computer and hold down Command + S keys to boot into Single User Mode.

Step 3: Release the keys until you see white text appears on the startup screen.

Step 4: Wait until you see root#appears at the bottom of the text.

Step 5: Run the following command:

Tips: Remember to replace 'hfs' with the file system on your external hard disk. For example, type fsck_msdos for FAT file system and type fsck_exfat for exFAT file system. Remember to replace disk3s2 with the Device name of your external hard disk too.

Step 6: Wait until the checking and repairing process is completed and run reboot command.

Hopefully, the command has helped you fix file system errors on your external hard drive. If your external hard drive is still not working properly after you reconnect it to the Mac, proceed to the last solution.

Solution 3: Reformat the external hard drive

If you have encountered the First Aid operation failure when trying to fix external hard drives and neither of the solutions above works, the disk is probably severely corrupted. The simplest and most efficient way is to reformat the corrupted external hard drive to make it workable again. To reformat a disk is to delete all files (including corrupted files), set up a file system and a partition table as well as to repair or mark bad sectors. Those are the main factors that cause disk corruption, so to reformat a disk can solve almost all disk problem you may come across. But before that, you'd better back up as many files as possible to another drive, just as Disk Utility suggested.

However, you probably won't be able to back up your files directly from the seriously corrupted external hard drive. In this situation, data recovery software comes for help.

Step 1: Recover as much data as possible with iBoysoft Data Recovery for Mac

iBoysoft Data Recovery for Mac is reliable external hard drive data recovery software for Mac users. It is able to recover deleted or lost data from unreadable/unmountable/formatted/corrupted external hard drives. In addition to external hard drive data recovery, it is also a tool that supports USB flash drive data recovery, SD card data recovery and so on. Moreover, it is a data recovery tool for Mac that supports data recovery for encrypted APFS disks. This software is fully compatible with macOS 10.15/10.14/10.13/10.12 and OS X 10.11/10.10/10.9/10.8/10.7.

Recover lost data from corrupted external hard drives with iBoysoft Data Recovery for Mac

Mac Disk First Aid Software Free

1. Download, install and launch iBoysoft Data Recovery for Mac.

2. Select the external hard drive that First Aid failed to repair and click Next. The program will start scanning this drive for recoverable files.

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3. Double-click the found files to preview after the scanning process finishes.

4. Select what you want to get back and click Recover.

5. Go through the recovered files and make sure all desired files are back.

Step 2: Erase/reformat the external hard drive in Disk Utility

1. Go to Finder > Applications > Utilities > Disk Utility.

2. Select the external hard drive and click Erase on the top toolbar.

3. Provide the required details including a name, a format, and a scheme.

4. Click on Erase button.

5. Wait until the process finishes.

If the external hard drive still doesn't work on Mac after reformatting, it's very possible that the external hard drive has been damaged physically. You have to send it to a local service center or replace it with a new one.

Mac Disk First Aid Software


Disk First Aid Windows 10

Disk Utility's First Aid repairing process doesn't fail on external hard drives only. It could happen to any external disks including pen drives, SD cards, memory sticks, etc. As a result, if you come cross First Aid operation failure on any external disks, this post can still be very helpful.