How to Fix Corrupted External Hard Drive on a Mac

A corrupted external hard drive poses a serious problem for Mac users, often leading to error messages, blocked file access, or sluggish performance. This article explains different methods to fix a corrupted external hard drive on your Mac using the tools and features available in macOS. These steps can help you save your data and restore your hard drive to working condition.

Signs of External Drive Corruption

One of the main tasks is to identify the first signs of a corrupted external hard drive, which is important for timely intervention and effective repair. Here are some common symptoms that indicate your external hard drive might be experiencing issues:

• 🚫 Error messages: Frequent alerts such as “Disk not readable” or “Error writing to disk” may appear when you attempt to access or write data to the drive.
• 🐌 Slow performance: A significant slowdown in data transfer speeds or prolonged delays in accessing files can be symptomatic of underlying drive problems.
• ❓ Missing files: Files that suddenly disappear or become inaccessible, even though they were not manually deleted, can signal corruption within the drive.
• 🔉 Strange noises: Unusual sounds like clicking or grinding from the drive often indicate physical damage, which can lead to data corruption.
• 🗃️ Inconsistent file listings: Changes in file or folder visibility without any user action suggest errors in the drive’s directory structures.

When these symptoms manifest, it’s important to proceed with a diagnostic approach using macOS’s built-in utilities, which can help determine the severity of the corruption and the necessary steps to fix the external hard drive on Mac.

How to Recover Data From a Corrupted External Hard Drive on a Mac

It’s critical to recover your files before try repair a corrupted hard drive. Some error correction methods can inadvertently damage existing data, and in some cases, the strain of these fixes can exacerbate the problem, especially on physically damaged disks.

Disk Drill is a comprehensive data recovery software that excels in recovering files from corrupted, damaged, or inaccessible external hard drives. It supports many file systems, including APFS, HFS, and exFAT, making it versatile for most hard drives. Additionally, Disk Drill is capable of signature recovery of about 400 file formats, enhancing its ability to retrieve various types of lost data. This software is particularly effective if the corrupted hard drive still appears in Disk Utility with the correct size, as it can access and attempt to recover a corrupted hard drive on a Mac under these conditions.

Note: If the disk shows signs of physical damage, use Disk Drill’s “Byte-to-byte Backup” feature to make a byte-by-byte copy of the drive. This reduces the load on the damaged disk during the recovery process but requires a target disk with free space greater than the total size of the problematic disk. This backup can then be scanned to recover data, protecting the original drive from additional stress.

1. Visit the CleverFiles website to download the latest version of Disk Drill for macOS. Install it by dragging the application icon to your Applications folder.
2. Open Disk Drill from your Applications folder. You may need to allow the application permissions to access your disk drives in your system’s security settings.
3. Connect your external hard drive to your Mac. If the drive is detectable, Disk Drill should list it under the available drives.
4. Select your external hard drive from the list and click the “Search for lost data” button to start scanning for recoverable data.
5. After the scan is complete, Disk Drill will display a list of recoverable files. You can filter and preview these files to check their contents and recovery viability.
6. Mark the files or folders you want to recover and click the “Recover” button. To avoid potential data overwriting, it’s advisable to recover the files to a different drive than the one recovered from.
7. Click the “Next” button to save the files to your chosen location.

How to Fix Corrupted External Hard Drive on Mac

Once you’ve identified signs of corruption in your external hard drive, the next step after data recovery is to attempt repairs using various methods available on your Mac. We will explore several approaches to address different aspects of drive corruption. With these guidelines, you can try to fix a corrupted hard drive using a Mac and restore its functionality.

1. Try DIY Methods

First of all, it’s a good idea to start with some simple do-it-yourself troubleshooting steps. These initial measures can often resolve common issues without specialized tools or interventions. Here are some simple techniques to try:

• Check that the USB or Thunderbolt cable connecting your external hard drive to your Mac is secure. Sometimes, simply reseating the cable can resolve connectivity issues.
• Switch the cable to a different port on your Mac. A faulty port can cause the drive to malfunction, so testing multiple ports can help isolate the issue.
• Cables can degrade or become faulty over time. Try a different cable to determine if the issue lies with the original one.
• Connect your external hard drive to another Mac to avoid system-specific issues. This step can help determine whether the problem is with the drive itself or your computer’s configuration.
• Direct connection to your Mac is more reliable than USB hubs, which can introduce connection instabilities or power inconsistencies.

These steps serve as a first line of defense against external hard drive issues. By systematically checking these elements, you can often identify and solve simple problems. If these measures do not resolve the issue, more advanced repair techniques using macOS’s built-in utilities, which we will explore in the next section, may be necessary.

2. Check Drive in Disk Utility

Disk Utility is a macOS tool designed to manage and diagnose issues with storage devices. It’s beneficial for verifying whether your external hard drive is recognized by your Mac and displayed with the correct size. This can be an initial indicator of the drive’s health and a preliminary step in troubleshooting drive issues. Here’s how you can utilize Disk Utility to check your external hard drive:

1. You can Access Disk Utility by navigating to the Utilities folder within your Applications folder or simply using Spotlight search to find and open Disk Utility.
2. In Disk Utility, go to the “View” menu and select “Show All Devices.” This provides that both drives and their corresponding partitions are visible in the sidebar.
3. Select the external hard drive you wish to check from the sidebar in Disk Utility. This step confirms whether your Mac recognizes the drive.
4. With the drive selected, examine the information displayed at the bottom of Disk Utility or click on the “Info” button for more detailed data. Check that the capacity and used space are accurately reported, which can confirm the drive’s proper functionality. You can also use specialized programs to check the drive’s health.
5. If the drive’s information appears correct and the drive is recognized, it’s a positive sign of its operational status. However, if the drive does not appear or shows incorrect data, it may indicate physical issues with the drive or connection.

If Disk Utility successfully identifies the drive with accurate information, this is a good indication that your system recognizes the hardware. However, if your drive still does not appear in the Finder, you need to follow the steps described below.

3. Mount Partition in Disk Utility

When your external hard drive is recognized by Disk Utility but isn’t mounting automatically, manually mounting the partition can be an effective troubleshooting step. This action can help restore access to your data if the drive itself doesn’t have severe physical or file system damage. Here’s how to manually mount a partition using Disk Utility:

1. Use Finder to navigate to the Applications folder, then Utilities, and open Disk Utility. Alternatively, use Spotlight to search and launch it directly.
2. In Disk Utility, find your external hard drive listed under the external section in the sidebar. Click on it to select it.
3. When the drive is selected, the partitions appear beneath the drive name. Select the partition you want to mount.
4. Click the “Mount” button at the top of the Disk Utility window or right-click on the partition and select “Mount”. If the mount button is greyed out, this could indicate that the system cannot mount the partition due to underlying issues.
5. After clicking mount, watch the partition appear on your Desktop or in the Finder sidebar. This indicates that the partition is now accessible.

If the partition does not mount or Disk Utility reports errors during the process, additional external hard drive repair on Mac may be necessary to resolve underlying file system issues. However, if the partition has been mounted in Disk Utility but is still not visible on the Desktop or the Finder sidebar, you may not have this display configured.

4. Show Drive in Finder

Check that your external hard drive is visible in Finder’s sidebar or on the desktop, which is important for easy access and management of its contents. Sometimes, settings in Finder may prevent drives from appearing properly. Adjusting these settings can help you to display all connected drives correctly. Here’s how to configure Finder to show your external hard drive:

1. Click on the Finder icon in your Dock to open a new Finder window.
2. In the Finder menu at the top of the screen, select ‘Settings’ or use the shortcut Command + “,“.
3. Click on the ‘Sidebar’ tab within the Finder Preferences window. Here, you can customize which items appear in the sidebar.
4. Under the ‘Locations’ section, use the checkbox ‘External disks’ to make all connected external hard drives visible in the Finder sidebar.
5. Navigate to the ‘General’ tab in the Finder Preferences. Make sure the ‘External disks’ option is checked under the ‘Show these items on the desktop’ section. This means that external hard drives appear on your Desktop as well.
6. Close the Preferences window to save your settings. Your external hard drive should now appear both in the Finder sidebar and on the Desktop, making it easier to access and manage.

By configuring these settings, you can make sure that your external hard drive is always visible when connected to your Mac. This visibility is necessary for monitoring your drive and quickly accessing its contents.

5. Reset SMC and NVRAM

Resetting the System Management Controller (SMC) and Non-Volatile Random-Access Memory (NVRAM) on your Mac can help resolve various hardware-related issues, including those affecting external hard drives. These resets can fix corrupted hard drives on Mac caused by problems related to power management, battery behavior, etc. Here’s how to properly reset the SMC and NVRAM:

Reset the SMC (for MacBooks with non-removable batteries and other Macs)

1. Shut down your Mac.
2. For MacBooks, hold down Shift + Control + Option on the left side of the built-in keyboard and press the power button at the same time. Hold these keys and the power button for 10 seconds.
3. For desktop Macs, unplug the power cord, wait 15 seconds, plug it back in, and wait another 5 seconds before turning it back on.
4. Release all keys and the power button at the same time.
5. Turn on your Mac.

Reset the NVRAM (only for Intel-based Macs)

1. Turn off your Mac.
2. Turn on your Mac and immediately press and hold Option + Command + P + R.
3. Hold these keys for about 20 seconds. On some Macs, the startup sound might play a second time, or the Apple logo might appear and disappear twice.
4. Release the keys after the second startup sound or the second appearance of the Apple logo.

After performing these resets, reconnect your external hard drive and check if the issues have been resolved. These steps can sometimes rectify seemingly stubborn hardware-related problems and are particularly useful if your Mac fails to recognize an external hard drive or if you encounter persistent issues after trying previous fixes.

6. Use First Aid for External Hard Drive

Disk Utility’s First Aid is a valuable tool for diagnosing and repairing file system issues on your external hard drive. This feature checks for various types of file system errors and attempts to correct them, which can resolve many common problems with corrupted drives. Here’s how to use First Aid to repair an external hard drive on a Mac:

1. Navigate to the Utilities folder within your Applications folder, or use Spotlight search to quickly find and open Disk Utility.
2. In the Disk Utility sidebar, locate and select your external hard drive. Ensure you choose the correct drive to avoid unintended operations on other drives.
3. With the drive selected, click on the “First Aid” button located at the top of the Disk Utility window. Confirm that you want to run First Aid by clicking “Run” in the prompt that appears.
4. Disk Utility will begin checking the drive for errors and attempt to repair them. Keep an eye on the progress bar and any messages that appear during this process.
5. Once First Aid is complete, review the final report. Disk Utility will provide a summary of any repairs made or notify you if the drive cannot be repaired.
6. If First Aid reports that repairs were successful, it’s advisable to restart your Mac and recheck the drive’s functionality. If the drive still shows signs of issues or if First Aid cannot repair it, further troubleshooting may be required.

First Aid in Disk Utility can often resolve minor file system errors and restore the functionality of your external hard drive. However, if this method does not fix the problem, more severe issues may be involved, requiring advanced recovery techniques or professional assistance.

7. Try Accessing the Hard Drive in Safe Mode

When you boot your Mac into Safe Mode, it provides a diagnostic approach to help you troubleshoot issues with an external hard drive. Safe Mode limits the Mac to its essential functions, preventing third-party software from interfering with the operating system and connected devices. Here’s how to access your hard drive in Safe Mode:

1. Turn on your Mac and immediately press and hold the Shift key. Release the Shift key when you see the login window. Note that startup is likely to take longer than usual.
2. Once your Mac starts in Safe Mode, connect your external hard drive. Check if the drive is recognized and whether you can access the files without the issues encountered during normal operation.
3. If the drive is accessible, perform critical operations, such as backing up data or transferring impossible files under normal conditions.
4. After testing, restart your Mac without holding any keys to exit Safe Mode and return to normal operation.

If accessing the hard drive in Safe Mode resolves the issues, it’s likely that non-essential software or drivers interfering during normal operation are to blame. Identifying and resolving these conflicts can improve the stability and functionality of your external hard drive. However, if problems persist even in Safe Mode, it may indicate more severe hardware issues or file system corruption that requires further investigation.

8. Use fsck Command To Repair File System

The File System Check (fsck) command is a powerful tool available in macOS’s Terminal that can help diagnose and repair file system issues on your external hard drive. It’s especially useful when the drive is not behaving as expected and graphical tools like Disk Utility haven’t resolved the issues. Here’s a step-by-step guide on how to use the fsck command to repair an external hard drive using a Mac terminal:

1. Open Terminal from your Applications folder or Utilities subfolder, or use Spotlight to search and launch it directly.
2. Enter the appropriate fsck command sudo fsck_hfs -fy (for HFS formatted drives) or sudo fsck_apfs -y (for APFS formatted drives).
3. Monitor the output in Terminal as fsck processes the file system. It will report any corrections it makes or notify you if no issues are found.
4. Once the fsck process completes, restart your Mac, applying any changes made during the repair process.

fsck command can be a more advanced method to repair file system issues, particularly useful when other simpler methods have failed. However, if fsck cannot fix the corruption, or if your drive continues to experience problems, further steps involving data recovery or professional assistance might be necessary.

9. Use TestDisk to Restore Partition

TestDisk is an advanced, open-source software tool designed to recover lost partitions and make non-booting disks bootable again. This tool can be incredibly useful when dealing with severe corruption or accidental deletion of partitions on your external hard drive. Here’s how to use TestDisk to attempt restoration of your drive’s partitions:

1. If you don’t already have Homebrew installed, open Terminal and enter the following command: /bin/bash -c “$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)”
2. After installing Homebrew, install TestDisk by typing brew install testdisk in Terminal and pressing Enter.
3. Once the installation is complete, type sudo testdisk in Terminal and press Enter to run the program with administrative privileges. You may need to enter your administrator password.
4. Follow the on-screen instructions to select your external hard drive from the list of available drives.
5. Choose the ‘Analyse’ option to search for lost partitions. TestDisk will scan your drive and attempt to find any deleted or damaged partitions.
6. If TestDisk finds partitions that can be recovered, it will display them. Select the partitions you wish to recover and follow the prompts to write the recovered partition structure back to the disk. Exercise caution during this step to avoid further data loss.
7. After completing the recovery process, exit TestDisk and reboot your Mac to ensure all changes take effect.

Using TestDisk can be a powerful method for fixing a corrupted external hard drive without formatting on a Mac and restoring access to data that was thought to be lost. However, due to its complex nature, it is recommended for more advanced users or those with specific recovery needs.

10. Format External Hard Drive

When all other methods have failed to repair your corrupted external hard drive, formatting remains the last resort to fix it. This process will erase all data on the drive, making it important to attempt data recovery before proceeding. We consider how to recover data from a corrupted hard drive on a Mac in the next section of the article. Formatting can resolve issues related to severe corruption, allowing you to use the drive again but at the cost of losing existing data. Here’s a step-by-step guide on how to format your external hard drive on a Mac:

1. Navigate to the Utilities folder within your Applications folder, or use Spotlight search to open Disk Utility.
2. In Disk Utility, locate and select your external hard drive from the list of available drives on the left panel.
3. Click the “Erase” button at the top of the Disk Utility window. You will be prompted to choose a file system format and a drive name.
4. Select a file system format suitable for your needs. Depending on your macOS version, choose APFS or Mac OS Extended (Journaled) for Mac compatibility, or choose exFAT for maximum compatibility with other OS.
5. After selecting the format and naming your drive, click “Erase” to begin formatting. Monitor the progress in Disk Utility.
6. Once the formatting is complete, Disk Utility will display a success message. Close Disk Utility and eject the drive properly before disconnecting it.
7. Reconnect your drive to verify that it appears correctly in Finder and is ready for use.

Formatting your external hard drive effectively resets it, providing a clean slate for new data. However, since this process erases all previous content, it should only be undertaken after all other recovery efforts have been exhausted.

11. Contact Data Recovery Services

Professional data recovery services are a good option when faced with a corrupted external hard drive that software tools cannot restore. These services are equipped to handle complex recovery scenarios beyond the reach of standard software solutions. This includes drives with severe physical damage, such as those affected by water or impact, and those suffering from serious mechanical failures like head crashes or motor issues.

Professional data recovery firms operate with advanced tools and technologies, often in controlled cleanroom environments, which are necessary for opening and repairing physically damaged drives without causing further harm. While professional data recovery can be expensive, the cost is often justified by the high success rates and the ability to recover data that would otherwise be permanently lost.

Conclusion

This article provides a comprehensive guide on how to fix a corrupted external hard drive on a Mac. It covers everything from initial signs of drive failure to detailed recovery processes. We also describe how to use advanced recovery software like Disk Drill and when you need to contact professional data recovery services.

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