Using the OS X Recovery tools, you can completely wipe your hard drive and reinstall the operating system without using a disk. You can remove all of your applications, settings and data using a backup of your current system. When you restore the operating system, you can choose to selectively install applications and data or reset the MacBook to its default settings without preserving any of your old data. For the security conscious, you can also use the Disk Utility to remove traces of data from the free space on your hard drive that a recovery utility could restore.
Create a Backup
Connect your MacBook to a power supply to prevent running down the battery while completing the installation process.
Click the "System Preferences" icon and select "Time Machine" to create a backup of your computer.
Attach an external drive with enough space to store all of your data to one of the ports on the side of your MacBook. Alternatively, use a Time Capsule or a storage device on your network.
Click the lock to make changes and provide your administrator credentials. Set the Time Machine toggle switch to the "On" position.
Click "Select Backup Disk..." and choose the disk you want to use to store your backup. Select the "Use Disk" button and wait for the backup to complete.
Reinstall Operating System
Access the OS X Recovery utilities by restarting your computer and holding "Command-R."
Connect your external hard drive to your MacBook using one of the available ports, if necessary.
Click the "Restore From a Time Machine Backup" option and choose "Continue" on the next screen.
Select the external hard disk connected to your computer and click "Continue." If you used a Time Capsule or network disk to store your backup, select the appropriate option and click "Connect to Remote Disk."
Provide any credentials needed to access your backup drive and click "Connect."
Choose the most recent backup to restore your files, settings and applications. Follow the prompts in the recovery wizard.
Click the drop-down arrows next to each type of content you want to install, when prompted. Check the boxes to install the specified content, or uncheck a box to skip the installation of the specified content. For example, restore your system without any of your settings or data by checking only the "Applications" option.
Securely Erase Free Space
Click the "Go" menu, select "Utilities" and choose "Disk Utility."
Launch "Disk Utility," select the main hard drive and click the "Erase" tab.
Click the "Erase Free Space..." button.
Select one of the options on the slider from Fastest to Most Secure and select the "Erase Free Space" button.
Things You Will Need
- External hard drive
- When erasing your hard disk, select "Fastest" to avoid securely erasing files on the disk, or click "Most Secure" to write over the data on the disk seven times. The fastest option leaves old data on your hard disk vulnerable to recovery with specialized disk utilities.
- Information in this article applies to OS X Mountain Lion. It may vary slightly or significantly with other versions or products.
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