How to Fix Mac Disk Errors in MacOS Recovery Mode

Hard Drive Disk

When you can’t boot up your Mac unit because of OS X-related errors, your only hope is the Disk Utility tool. The tool is used to repair Mac disk errors in your Mac such as corrupted files, non-responsive external devices, or the suddenly quitting of multiple apps. It can also be used to erase or reformat a disk, scan for physical errors on the disk, and repair disk permissions. Aside from Disk Utility, you can also use third-party tools to scan your computer for errors and pinpoint issues to resolve.

But what if the problem is access to the Disk Utility or any 3rd party tools because your computer won’t start? Don’t worry, because your Mac can let you launch a standalone version the machine’s Disk Utility from your computer’s built-in recovery partition. The idea is to boot your Mac into Recovery Mode first and then run the repair function from there to repair the disk. You don’t need to use an external disk boot drive to resolve the error because you can do that using OS X’s Recovery Partition.

What is the Recovery Mode

Recovery Mode is your Mac’s only hope when it encounters issues that prevent your computer from doing anything valuable. You have two options to fix it, the first one is to reinstall the updated version of your OS X and the 2nd option is to run a diagnostic scan using Disk Utility.

Reinstalling OS X can be done by rolling back to an earlier version using Time Machine, installing a new copy of your OS X over a pre-installed copy to fix some issues, or to completely erase the disk and install a fresh copy of your OS X. Your choice will depend on the type and the severity of your Mac disk error.

Here are the steps to follow on how to use Mac recovery mode to repair the disk errors:

  1. Go to the Apple Menu and click Restart.
  2. As your computer restarts, press Command + R when you hear the startup sound.
  3. Hold the key combination until the Apple logo appears.
  4. Choose Disk Utility when the OS X Utilities pop-up appears.
  5. Click Continue.
  6. Choose the volume you want to repair and then click the First Aid button.
  7. Click Repair Disk.
  8. There are two results that could happen after you run the Repair function: the disk has been repaired or you need to do something to fix the error.
    • If the error says, overlapped extent allocation, this means that two or more files exist in the same space on your disk and one of them could be corrupted. Check each file on the list if you can replace or re-create it. If not, open the file and decide if you need to delete it.
    • If the message says, the underlying task reported failure, this means that the repair was not successful and you have to run it again. If the repair still fails, back up your files and reformat the disk. Then, reinstall a fresh copy of the OS X. However, if the damage to the disk is physical, there is nothing you can do but replace it.

Other Options For You

But what if the Recovery Partition itself is damaged and you can’t access the recovery system? This usually happens when there’s a physical damage to the disk or you have replaced your startup disk.

In this case, your only option is to download an image of the Recovery System from Apple’s website and boot your Mac from it. This is called the Internet Recovery feature. However, this is only available for newer versions of Mac like OS X Lion. Internet Recovery has the same function as the Recovery Mode but you need to be connected to the Internet to be able to download the boot-up file from Apple’s servers.

To run the Internet Recovery feature, follow these steps:

  1. Go to Apple Menu and choose Restart.
  2. Hold down Command + Option + R when you hear the startup sound.
  3. If your computer is not connected to the Internet via Ethernet, you will be asked to connect to Wi-Fi.
  4. Once the Recovery System image has been downloaded, your Mac will start up with it and you’ll be able to access the same recovery tools of the regular Recovery Mode.

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