Trying to fix a corrupted hard drive on your Mac?
There are more than several ways to fix a Mac hard drive. Whether you’re having trouble with an external device or with the storage inside your Mac, we have all the steps you need to know to fix this issue.
Signs of a Corrupted External Hard Drive
External storage devices like a hard drive, especially HDDs, are more prone to being corrupted because of how they’re built. HDDs continually spin a disk that stores your files, and vibrations or sudden forces can move or damage the disk.
Here are some clear signs that your external hard drive is corrupted:
- 📄 Your Mac can’t read files from it.
- 💽 Your Mac doesn’t recognize the hard drive.
- 🔒 An error message like “The disk you inserted is not readable” appears.
If you aren’t getting any of these errors at all, not even a prompt from your Mac that the hard drive was inserted, then the problem might be something else. Contrary to popular belief and gaming culture, don’t blow into your hard drive USB connector like a Nintendo cartridge. There may be something wrong with the wiring of your hard drive, rather than damage in the disk or main storage chip.
Signs of a Corrupted Internal Hard Drive
Although Apple is known for its security, your Mac’s internal hard drive isn’t totally immune to getting corrupted. You may have installed a malicious program or had a recent crash that caused unsaved, corrupted files to appear in your system.
Here are some clear signs that your Mac hard drive is corrupted:
- 📛 Some applications or files don’t open.
- ❌ Applications randomly close or stop responding to input entirely.
- ↔️ You can’t transfer new files to certain folders.
- ☠️ Your Mac has trouble starting up.
Fixing Corrupted External Hard Drives On a Mac
With all that said, thankfully there are as many ways to fix these problems as there are symptoms for it!
Using Disk Drill to Backup Corrupted Hard Drive Data
Before we start tinkering with settings and trying to fix the hard drive on your Mac, let’s make sure we save and backup all the data inside it first. If worse comes to worst, we might have to reformat your hard drive.
If you’re backing up an external hard drive, you can just use your Mac for the backup files if you have any space. However, if you’re backing up your Mac’s files, then you’ll need a functional external hard drive for the backup files.
Backing up your files can take more or less 30 minutes, depending on the size of the files you’re saving.
- You can start by downloading Disk Drill from their official website. While that’s downloading, go ahead and connect your external drive to your Mac.
- When that’s done, just install the program by dragging it to your Applications folder and then launching it.
- After launching the program, select byte-to-byte backup in the left panel.
- When you’re there, click on the disk you want to backup.
- After, look for and click on the Create backup button.
- Choose a location and click on Save when you’re done.
Now that you’re done backing up your files, we can go troubleshoot the issue with your hard drive. The steps for recovering and restoring your backed-up files will be listed below at the end of the article.
In the meantime, we recommend making another backup and then scanning that with Disk Drill.
Scanning and Recovering Files From Your Byte-By-Byte Backup
Every time you use a third-party tool to scan and recover files, you risk overwriting your drive or even making the corruption worse. Whenever you’re recovering data, the main thing to avoid is overwriting the data on the drive you’re recovering from.
So, creating a byte-by-byte backup and then scanning that instead is a surefire way to preserve your original files and scan the new backup without fear of losing your data.
- Keeping the integrity of your original files.
- Having a backup with all your data.
- Having a backup you can scan repeatedly without fear of something bad happening to your data.
This way, even if your original disk is corrupted, you don’t have to worry about having only one chance to recover your files.
Here’s how you can do that:
- First off, go ahead and download Disk Drill into your Mac and install the program.
- When it’s installed, open up the program and select the storage device you want to scan. This should be the byte-by-byte backup drive that you just made.
- Although you can choose between different types of recovery modes, we recommend going with the All recovery methods option.
- From there, go and click on the Search for lost data button at the bottom-right corner of your screen. This process will take between several minutes to maybe half an hour depending on the size and speed of your storage device.
- Once the scan is finished, you can review all the files on a separate window by clicking on Review found items. There, you can preview all the Pictures, Videos, Audio, Documents, and Archives that Disk Drill managed to find.
- On the new window, sort the files to help you look for your lost data. You can use the options to the left-side of your screen to filter the results.
- Finally, simply click on the files you want to recover and select Recover at the bottom-right side of your screen.
You can repeat this process again and again with a byte-by-byte backup without the fear of losing your data.
Make Sure Your External Disks are Visible
There’s a macOS setting that’s responsible for showing hard disks, CDs, DVDs, and more on your desktop. If you can’t find your hard drive, it might be hidden and not corrupted. Hopefully, this is the case, so you won’t have to repair your hard drive later on.
Here’s how you can make your external disks visible through Finder:
- Open up Finder and click on the Finder tab at the top-left corner of your screen.
- From there, click on Preferences and look for the General tab.
- You’ll see a whole list of checkboxes. Click on External disks and make sure it’s enabled.
If this option was disabled when you opened Finder Preferences, then this should fix your problem. Go and look for your hard drive on your desktop.
Force Mount Your Hard Drive in Disk Utility
Even though your hard drive is connected, a simple tug from the wire can disconnect it. At the same time, a faulty hard drive may also have a hard time connecting to your Mac.
You can try to forcefully mount your hard drive using Disk Utility. This lets your Mac actively try to read and mount any hard drive that’s plugged into it.
Here’s how you can force mount your hard drive:
- Start by opening up the Disk Utility app.
- At the left-hand side of your screen, look for and right-click the external hard drive you’re having a problem with.
- In the quick-access menu, select Mount to force your Mac to read the drive.
Hopefully, this will let your Mac recognize your hard drive and help you recover data from it.
Try Some General Suggestions
These are quick and easy fixes that might help fix and connect your hard drive.
🐌 Do a Super Slow Jam
🔌 Connect to a Different Port
📏 Straighten Hard Drive Wire
❌ Don’t use a USB Hub
View Console Reports from Your Mac About the Hard Drive
Console reports are a great way to know what’s happening behind the scenes. Even if you don’t see the hard drive on your desktop, the activity should still be reported to the Console along with other reported problems.
- Open the Console app on your Mac through Spotlight or Finder.
- Click on View a report and select a report category in the sidebar. Look for any issues regarding your hard drive and see which errors are popping out. Here’s a basic guide.
- Crash Reports – details on apps or processes that have recently crashed.
- Spin Reports – details on app or process issues.
- Log Reports – system and use reports on specific apps and their respective events.
- Diagnostic Reports – details on how your hardware resources are performing.
You won’t need to look at Mac Analytics Data and system.log reports for this issue. Look for the reason why your drive isn’t mounting. It should state if the problem is due to a crash, corrupted file, or simply being unable to read and connect the hard drive to your Mac.
Use First Aid from Disk Utility
Disk Utility has a ton of features that are designed for hard drives and First Aid is one of them. It is designed to fix and repair errors on storage devices.
If the storage device you’re checking is your startup disk or startup volume, you’ll have to restart your Mac in macOS recovery first.
- Open up the Disk Utility app on your Mac. You can do this through Spotlight or Finder.
- Click on View and select Show All Devices.
- You should find the volume that needs fixing in the sidebar. Click on the First Aid button to fix that device.
- In the First Aid pop-up that opens, click on Run and follow the instructions.
- Repeat steps 3 and 4 for all the volumes on the storage device.
- When that’s done, select the container and click on the First Aid button.
- Again, click on Run from the dialog box and follow the instructions.
- Repeat steps 6 and 7 for each container on that storage device.
- Now, from the sidebar, select the storage device and press the First Aid button again.
- Go through the First Aid dialog box, click Run, and breeze through the instructions.
Finally, if Disk Drill tells you that your disk is about to fail, back up your data as much as and as quickly as possible. You will have to replace the disk through a certified Apple repair shop.
- Open up the Terminal through the Dock or Spotlight.
- Copy-paste this code into the Terminal command line: diskutil repairVolume /Volumes/[Drive Name]. Replace “[Drive Name]” with the appropriate name of the hard drive on your Mac.
This can take around a couple of minutes, so now would be the perfect time to brew yourself a cup of coffee or take a stretch.
Reset Your SMC
A built-in chip on the logic board of your Mac called the SMC is responsible for multiple functions, primarily with power and settings configurations of your macOS. The parameters of the chip often change, sometimes causing a malfunction that a good reset can fix.
Resetting the SMC will revert settings on your computer which might fix the corrupted hard drive issue where it’s either not connecting or not being read. It’s a bit of a long shot, but everything helps when you’re troubleshooting hardware problems like this.
💻 MacBooks with the M1 chip:
🔌 MacBooks with non-removable batteries:
- Start by powering off your Mac.
- After several seconds, press the Shift + Control + Option with your left hand. Use your right hand to hold down the power button at the top-left corner of your keyboard.
- Press these four buttons together at the same time and hold them for more than 10 seconds.
- Release all the keys and then turn on your Mac by pressing the power button.
🔋 MacBooks with removable batteries:
- Shut down your Mac and remove the battery.
- Press and hold the power button for around five seconds.
- Reinstall the battery and press the power button again to turn your Mac back on.
🛡️ MacBooks that have the T2 chip:
- Shut down your Mac, just like the previous steps.
- Press and hold Control + Option at the left side and Shift at the right side of your keyboard for about 7 seconds.
- After 7 seconds, press and hold the power button as well. Hold all four keys down for another 7 seconds before releasing them.
- Wait for a couple of seconds and then turn on your Mac.
🔩 Desktop computers that have the T2 chip and intel based mac`s:
- Like all the steps above, shut down your Mac and unplug the power cord.
- After a good 15 seconds, plug the power cord back in.
- Wait for exactly 5 seconds before turning on your Mac by pressing the power button.
Resetting Your NVRAM
Here’s another method that involves resetting something. Your NVRAM is responsible for storing your preferences and settings. Although the data stored isn’t personal data, resetting it does revert the personal preferences that you’ve previously set on your Mac’s settings.
Here’s how you can quickly do that:
- Shut down your Mac.
- Power it back on.
- When you press the power button, immediately press the Option + Command + P + R keys for a good 20 seconds. Your Mac might seemingly restart during the process, but that’s normal.
On Mac computers that play a startup sound, you can release the keys right after the second startup sound.
For Macs with the T2 Security Chip, you can take your fingers off the keys when the Apple logo appears and disappears on your screen after a second time.
You can see if you did this correctly by opening up your System Preferences window and checking if the settings were reverted to their default states.
For M1 Macs, you can simply shut down your computer and then power it back on. After a complete shutdown, your Mac tests the NVRAM for defaults and will reset automatically if something is wrong.
Uninstall SMART Utilities
SMART programs are a great way to keep track of the health of your hard drive, but they can also block certain storage types from connecting to your Mac. For example, a known issue with SAT SMART drivers is that it doesn’t allow LaCie or Drobo drives to mount.
There are a few ways you can uninstall these programs:
- Open up the Finder app and look for the SMART utility installed in your computer. Drag it to the Trash and then right-click the Trash icon. Select Empty Trash to begin uninstalling.
- Use the built-in uninstaller that comes with the SMART drive program you installed. It should be in the folder together with the SMART drive. If it isn’t there, try opening the SMART utility and looking for an uninstall option.
For example, SAT SMART uninstallations happen this way:
- Open up the Terminal.
- Copy-paste the command sudo rm-r /Library/Extensions/SATSMARTDriver.kext.
- After that, copy-paste the second command sudo rm -r /Library/Extensions/SATSMARTLib.plugin.
Boot Your Mac in Safe Mode
Macs are one of the safest laptops or desktops you can use, and for good reason. It’s strict when it comes to any signs of malicious behavior, even if it is from your trust hard drive. There’s a huge chance that your Mac considers your hard drive malicious and therefore doesn’t open it.
Similarly, you may also have other apps open that are preventing you from accessing your hard drive.
🛡️ Here’s how you can boot in Safe Mode for Macs with Intel CPUs and T2 security chips:
- Shut down your Mac.
- Wait for about 10 seconds, then power on your Mac by pressing the power button.
- Immediately press and hold the Shift key all the way until you see the login window.
💻 For Macs with Apple silicon, follow these steps:
- Shut down your Mac just like the previous step.
- After 10 seconds, press and hold the power button to turn your Mac on, all the way until the startup option window appears. That will show all the available startup disks and Options on your Mac.
- Select the startup disk you want to open.
- Press and hold Shift, click Continue in safe mode, and then release the Shift key.
✅ Here’s how to check if you did it correctly and booted up in Safe Mode:
- Click on the Apple menu.
- Look for and select About This Mac.
- Navigate to the Overview tab and select the System Report button.
- Click on Software at the left-side menu. In the System Software Overview section, look for the Boot Mode and see if it says either “Safe” or “Normal”.
Rebuild HFS Tree with FSCK Command
An HFS tree (Hierarchical File System) is a system developed by Apple to specify how data is arranged or allowed to exist on a drive. Your HFS tree might have issues, which is what’s causing the data-reading problem.
To run this command, you’ll have to restart your Mac and login as an Administrator. If you’ve done that, go ahead and proceed to the steps below.
- Open up the Terminal on your Mac.
- When that’s done, type out sudo diskutil unmount /dev/disk1s2 and press Enter. Replace the disk1s2 numbers with the correct ones in your drive. You can look for the number of your drive by opening Disk Utility, selecting your hard drive, and clicking on info at the top-right corner of your screen. This will open your hard drive details, but just look for your BSD device node information.
- After that, enter the command sudo fsck_hfs -f /dev/disk1s2.
- -f — forces a filesystem check even if the OS X says the filesystem doesn’t need it.
- -n — reports the errors it finds. Doesn’t fix the errors.
- -y — fixes errors automatically. Only use this if you know what you’re doing. Any mishaps can seriously mess up a filesystem.
This entire process can take a couple of minutes depending on the speed of your Mac. Reconnect the drive after the operation.
Format Your Hard Drive
For the last step on this article, we’re going to be formatting your hard drive. This will erase all the files on your hard drive.
Formatting your hard drive is essential when your drive is badly corrupted. If the repair tools couldn’t help with the errors, backup your files as best as you can and then reformat the drive.
- Open Disk Utility on your Mac.
- Click on the External Hard Drive you want to format at the left-hand side of your screen.
- Look for and press the Erase button. You can also right-click the hard drive and just click Erase from there.
- Give the soon-to-be-formatted hard drive a new name.
- We recommend choosing APFS, but you can choose whichever you want as the storage and file format. Select GUID as the Scheme.
- When that’s all configured, click on Erase to start the process.
After your hard drive has been reformatted, safely eject it with the steps below and then plug it back to your Mac. Your computer should read the external hard drive successfully and consistently from now on.
Disconnect Your Device Properly
If you somehow managed to repair the external hard drive on your Mac, let’s make sure that this problem doesn’t come up again.
There’s a step-by-step process to disconnecting your external hard drives properly. Unplugging it without going through those steps can cause errors, corrupted files, and even damage to your hard drive.
You can properly remove external drives by dragging the hard drive icon from the desktop to the Eject icon on the Dock. The Trash icon changes to the Eject icon during this process.
Alternatively, you can also Ctrl + Click the drive and click on Eject from the quick access menu.
Losing a hard drive can be such a huge problem, especially for the creatives who need it for files or for sentimental people keeping memories. While it’s inevitable for a hard drive to eventually break down and become obsolete, there are a ton of ways to recover and restore the health of a hard drive for another year.
Let me know on Twitter or LinkedIn if you need any help with fixing your hard drives!