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How to Repair Your Mac Startup Disk With Disk Utility: 3 Simple Steps

Repair your Mac’s startup disk easily with Disk Utility.

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Last updated: December 9, 2023

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To repair your Mac startup disk, follow these steps:

  1. Boot your Mac into Recovery Mode.
  2. Select your startup disk.
  3. Run First Aid using Disk Utility on each disk, container, and volume.

Before running Disk Utility, try basic troubleshooting steps like rebooting your Mac, scanning for viruses, decluttering, freeing up RAM, and updating macOS.

Like many Mac users, I’ve also faced slow performance, crashes, and even the dreaded spinning wheel of death, all leading to a malfunctioning startup disk. But you don’t have to spend a fortune on repairs if that happens. Instead, there’s a simple solution I’ve found: Disk Utility. In this guide, I’ll share three easy steps to repair your Mac startup disk using Disk Utility.

Before We Begin

Sometimes, you may think your Mac startup disk needs repair, while the actual issue may be malware or lack of storage. Download MacKeeper to scan your Mac for issues and rule out other potential problems before Mac startup repair.

Basic Mac Troubleshooting Before Startup Disk Repair

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Sometimes, your Mac’s unusual behavior is nothing but a false alarm. If your system is running slow, apps are crashing, files are becoming corrupted, or you’re getting the spinning pinwheel frequently, your Mac’s startup disk may be full instead of damaged.

So, before jumping right to Mac disk repair, try simpler solutions first.

1. Turn Your Mac Off and On Again

First things first – have you tried turning it off and on again? I know it sounds cliche, but sometimes, all your Mac needs is a good old reboot to get things back on track.

To turn off your Mac, click the Apple icon and select Shut Down.

click the apple icon and select shut down

Wait a few seconds and press the Power button to turn it on again. If the issue isn’t severe, it should be fixed after the restart.

2. Run A Virus Scan

Next up, try running a malware scan. There are plenty of antivirus programs out there that can help you scan and remove any malicious software. I recommend using MacKeeper to scan your Mac for viruses.

Here’s how you can run a virus scan on your Mac using MacKeeper:

  1. Download and install MacKeeper on your Mac.
  2. Open MacKeeper and click Antivirus in the left sidebar.
click antivirus under the security section
  1. Click Start Scan.
click start scan in mackeeper antivirus
  1. MacKeeper will start scanning your system. This step can take a while, depending on the number of files on your Mac.
  1. Once the scan is complete, you’ll see a report. If there are no viruses on your Mac, you’ll get a No threats found message. If unsatisfied with the results, click Restart to run the scan again.
click restart to finish the process

3. Declutter Your Hard Drive

If your Mac is still acting up, try clearing space on your hard drive. A cluttered hard drive can cause many issues, including slow performance and crashes.

Here are some tips to declutter your Mac:

  1. 🧹 Find and Remove Unnecessary Files: First up, find those files you don’t need anymore. I’m talking about old documents, random downloads, apps you never use, duplicates – you know, the usual suspects. I use the Finder app to find large files and delete the stuff I don’t need.
  2. 🚮 Uninstall Unused Applications: It’s a good idea to uninstall unused apps on Mac. You can do this by dragging the app to the Bin or using an uninstaller like MacKeeper.
  3. 💾 Delete Old Backups and Downloads: Your Mac might be hoarding old backups and downloads without you even realizing it. I regularly check for these and clear them out to free up space on Mac.
  4. 🧼 Clean Up Cache Files: Cache files are temporary files created by apps and can take up a lot of disk space. You can use a cache cleaner (MacKeeper’s my go-to) to remove cache files from your Mac.
  5. 🗑️ Empty the Trash: Last but not least, don’t forget to take out the trash – literally. After you delete files, empty the Trash on your Mac to really clear them from your hard drive.
right click the bin and select empty bin

4. Free Up Some Memory

Freeing up memory on your Mac can improve its performance and speed. Here are some steps you can follow to free up RAM on your Mac:

  • 🚫 Close Unused Applications: If you have unused apps running in the background, close them. This will free up memory and make your Mac run faster.
  • 🔍 Check for Memory-Hungry Apps: Use Activity Monitor app to see which apps use the most memory. If you find any memory-hungry apps, close or quit them to free up memory.
  • 🚀 Remove Login Items: Login items are apps that start up automatically when you log in to your Mac. Too many login items can slow down your Mac. Remove login items on your Mac by going to System Settings > General > Login Items. Alternatively, you can use MacKeeper to remove login items in just a few clicks.
  • 🌐 Clear Browser Cache and History: Your web browser may use a lot of memory by storing cache and browsing history. Clearing the browser cache on Mac can free up memory and improve your Mac’s performance.
  • 🧹 Use a Memory Cleaner: You can also use a memory cleaner app like MacKeeper to run regular checks for memory usage. Here’s how:
  1. Download and install MacKeeper on your Mac.
  2. Open MacKeeper and click Memory Cleaner in the left sidebar.
select memory cleaner under performance
  1. Click Open.
click open in the memory cleaner
  1. You’ll see the occupied and available memory. Tap Clean Memory.
click clean memory
  1. This will clean your Mac’s memory, and you’ll see how much memory it cleaned in the Last Cleanup.
memory cleaned after a cycle

What Else Can MacKeeper Do?

Besides cleaning memory and checking your Mac for malware, MacKeeper offers other features like cleaning junk files on Mac, changing startup programs, and uninstalling unused apps on Mac. Check out my detailed MacKeeper review to learn more about its features.

5. Update Your Software

Finally, make sure your software is up to date. Apple releases updates to improve performance and fix bugs, so keeping your Mac’s software current is essential for a smooth experience.

Here are the steps to update macOS on your Mac:

  1. Click the Apple icon in the top-left corner of your screen and select System Settings.
click the apple icon and select system settings
  1. Click General and select Software Update to open the software update window.
click general and select software update
  1. Your Mac will check for available updates. If any updates are available, click the Update Now button to start the update process.
click the update now button
  1. Depending on the update’s size, it may take several minutes to download and install.
  1. Once the update is complete, your Mac will restart if necessary.

If you’ve tried all these steps and your Mac is still misbehaving, it’s time to move on to repair your Mac startup disk.

How to Repair Your Mac Startup Disk With Disk Utility

Before I show you how to fix startup disk on Mac, you should take some precautionary steps, like backing up your data to avoid data loss. Then, follow the steps below to prepare and repair your Mac startup disk using Disk Utility.

Depending on your Mac startup disk health, set aside enough time for this task – around five minutes for healthy disks and up to two hours for damaged or corrupted ones.

Step 1: Back Up Your Data Before Repairing Your Disk

Before diving into disk repairs, remember it’s a bit risky and can lead to data loss. That’s why backing up your files is crucial. I’ve learned this the hard way and now always make sure to have a backup plan.

Here are some ways to back up your data on Mac:

  1. ⌛️ Use Time Machine: Time Machine is a built-in backup feature in macOS. You can easily back up your Mac data using Time Machine. You can also use Time Machine to restore deleted files on Mac.
  2. ☁️ Use iCloud: iCloud is Apple’s cloud storage service that allows you to back up your files to the cloud. I use it to ensure my important documents and photos are always just a click away.
  3. 💾 Use an External Hard Drive: You can also go old school and use an external hard drive to back up your files manually. Simply connect the external drive to your Mac, then drag and drop your files onto the drive.

Step 2: Boot Your Mac Into Recovery Mode

To repair the startup disk on your Mac, you must first boot it into Recovery Mode. That’s because the startup disk cannot be repaired while it is being used by macOS. By booting your Mac into Recovery Mode, you can use a separate partition to run macOS and bypass this limitation.

The steps for booting your Mac into Recovery Mode differ for Apple Silicon and Intel-based Macs. If you’re unsure about your Mac’s processor, check the Apple Support Page.

Follow the steps for your respective Mac model below:

On Apple Silicon Mac

To initiate Recovery Mode on an Apple Silicon Mac, follow these steps:

  1. Shut down your Mac and wait for it to power off fully.
  2. Press the Power button to restart your Mac.
macbook air touch id
  1. Keep holding down the Power button until the startup options page appears. Select Options.
click options on startup options page
  1. If prompted, provide your administrator password to log in to your user account.

On Intel-Based Mac

To initiate Recovery Mode on an Intel-powered Mac, follow these steps:

  1. Shut down your Mac and wait for it to power off fully.
  2. Press the Power button to start up your Mac.
macbook air touch id
  1. Immediately press and hold the Command ⌘ + R keys.
macbook air command r keys
  1. Keep holding both keys until the macOS Recovery screen appears.
macos recovery screen
  1. If prompted, provide your administrator password to log in to your user account.

Step 3: Select Your Disk and Run First Aid

Now that you have booted your Mac into Recovery Mode, you can start repairing your disk. Here’s how to do it:

  1. Click Disk Utility on the macOS Recovery screen and tap Continue.
select disk utility from macos recovery screen
  1. Click the View icon in the top left corner and select Show All Devices from the drop-down menu.
click the view icon and select show all devices
  1. In the left-hand sidebar, you’ll see all connected disks, containers, and volumes on your Mac in a nested form. The order is Disk > Container > Volume, with each level nested inside the previous one.
disk container volumes in disk utility
  1. Select the volume, container, or disk you want to repair from the sidebar. Start with the bottom volume and work your way up before moving to the containers and the disk.
  2. Click the First Aid button at the top of Disk Utility.
select startup disk and click first aid
  1. Click Run on the pop-up window. You may be asked to enter your administrator password.
click run on the first aid prompt
  1. Wait for First Aid to complete, and then click Done. Repeat these steps for the next volume, container, or disk.
  2. After repairing all of the disks on your Mac, go to Apple > Restart from the menu bar and restart your Mac.
click the apple icon and select restart

What to Do After Running First Aid on Your Startup Disk

  • If Disk Utility indicates your disk is in good condition or has been fixed, your task is complete. For more details on the repairs, click Show Details.
  • If you get “overlapped extent allocation” errors, multiple files share the same space on your disk, causing potential corruption. Check each file listed, typically found in a DamagedFiles folder at your disk’s top level. Replace or recreate the file if possible. If the file holds important data, open it to confirm the integrity of its contents.
  • If Disk Utility fails to repair your disk or reports a First Aid process failure, attempt another repair. If this fails, protect your data by backing up, reformatting the disk, reinstalling macOS, and restoring your data.
  • Persistent disk issues or an irreparable disk suggest physical damage. In such cases, consider servicing or replacing your disk.

How to Know If Your Mac Startup Disk Is Damaged

Knowing if your Mac’s startup disk is damaged is key to maintaining your computer’s health and performance. Here are some telltale signs to watch out for:

  • 🐢 Mac Running Slow: When the disk becomes fragmented or develops bad sectors, your Mac takes longer to find and use data, making everything slow.
  • 💥 Applications Crashing on Mac: The damaged disk may struggle to read and write necessary files. It causes frequent app crashes, freezes, or unexpected termination of software.
  • 🚫 Files Becoming Corrupted: A damaged startup disk can lead to file corruption, making them unreadable or causing data loss. Files may become partially or entirely inaccessible, so you can’t open or modify them.
  • 🌀 Spinning Pinwheel of Death: Seeing a lot of spinning pinwheels? That’s a sign your Mac is struggling to do its job because of disk read/write issues.
  • ⚠️ Error Messages During Startup: A damaged startup disk can trigger various error messages during the system boot process. These error messages may indicate disk corruption, missing system files, or other disk-related issues.

Fix Disk Errors With Disk Utility on Mac

Keeping your Mac’s startup disk healthy is essential for your system to function properly. If you’re experiencing issues with your Mac, repair your startup disk as soon as possible. But if the Disk Utility doesn’t work, there are other ways to fix your Mac:

Frequently Asked Questions

  1. What is the startup disk on a Mac?

    The startup disk on a Mac is the hard drive or solid-state drive containing the operating system. It’s where the Mac boots from when powered on, holding all essential system files and user data, making it a critical component for the Mac’s functionality.

  2. Can I repair my Mac startup disk without losing my data?

    Yes, you can repair your Mac startup disk without losing your data in most cases. However, it’s always a good idea to back up your data on macOS before attempting any repairs, just in case.

  3. How often should I repair my Mac startup disk?

    You should repair your Mac startup disk every few months to keep it healthy and prevent any performance issues. However, resort to disk repair only after trying easier solutions to optimize your Mac.

  4. How long does it take to repair a Mac startup disk using Disk Utility?

    Repairing a Mac startup disk using Disk Utility can take a few minutes to several hours. However, the exact time can vary depending on the size of the disk, the amount of data stored on the disk, the Mac’s speed, and the severity of the disk errors.

Hashir Ibrahim


I'm Hashir, a tech journalist with a decade of experience. My work has been featured in some of the top tech publications like MakeUseOf and MakeTechEasier. I have a bachelor's degree in IT, a master's in cybersecurity, and extensive knowledge of Apple hardware, specifically MacBooks. As the senior writer at MacBook Journal, I write in depth guides that help you solve any issues you have with your mac and unbiased reviews that help you make the right buying decisions.



Hi there! I'm Ojash, a tech journalist with over a decade of experience in the industry. I've had the privilege of contributing to some of the world's largest tech publications, making my mark as a respected Mac expert. My passion lies in exploring, using, and writing about MacBooks, and I enjoy sharing my expertise to help others make informed decisions and get the most out of their MacBook experience. Join me as we delve into the fascinating world of MacBooks together!

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