How to Erase External Drives Securely Using Disk Utility on MacOS – Guide
Protecting your personal data is essential when disposing of an old computer. Before you discard or sell it, make sure to securely erase all emails, contacts, documents and other sensitive information stored on the device and its external drives. Failing to do so could leave you vulnerable to hackers seeking access to passwords or identity data.
Erasing an uninitialized volume
Erasing a volume is an effective way to quickly free up disk space for multimedia applications like Adobe Photoshop. Rather than using third-party defrag tools, some savvy users create small volumes to store data for one project and then erase the volume before starting the next, thus ensuring their applications have enough contiguous space to function efficiently.
This guide outlines a data erasure method that does not guarantee security of erased data. While the process may delete files, most data recovery programs can still resurrect them. To ensure security, use the secure erase procedure outlined later in this guide.
Choose a disk or volume from the list in the Disk Utility window. Identify it by its name and icon, which should match what appears on your Mac desktop.
To delete a volume, click the Delete tab in Disk Utility and the name and format of the selected volume will be displayed on the right side of the workspace.
Delete the desktop volume with Disk Utility to quickly and easily remount it.
Securely erase a volume
Disk Utility offers four ways to securely erase data from a volume, ranging from basic to meeting US Department of Defense standards.
Securely erase your data to ensure it can’t be recovered by anyone else.
Choose a disk or volume from the list in Disk Utility’s left pane. Each item is labeled with the same name and icon as it appears on your Mac’s desktop.
To delete a volume, click the Delete tab in Disk Utility and the name and format of the selected volume will be displayed on the right side of the workspace.
To protect your data, Mac OS offers various erasure options that can be accessed by selecting Security Options.
Options for OS X Snow Leopard and earlier:
Do not delete data:
This method may be speedy, but it is not secure: the volume catalog directory is removed, yet the data remains.
Reset data:
This method of data erasure provides a secure solution, with the time taken to complete the process dependent on the size of the volume.
Deletion of 7 tickets:
This erasure method meets the US Department of Defense’s security standards, but it can be time-consuming.
Deletion of 35 passes:
Disk Utility’s data deletion security is at its peak, with 35 overwrites of a volume. This method of erasure is here to stay.
Options for OS X Lion through OS X Yosemite
Secure Erase Options now feature a slider instead of a list of options, allowing users to quickly and easily select the desired level of security.
The fastest:
This method of erasing data is the quickest, but it does not prevent deleted files from being recovered by specialized software.
Reset the data:
Erasing a volume or disk with this method overwrites all locations with zeros, making data recovery difficult and time-consuming.
Three passes:
This secure erase meets Department of Energy standards, writing two random data passes followed by a single pass of a known data pattern to the volume or disk.
Safer:
This method of securely erasing a volume or disk meets the US Department of Defense’s stringent requirements for secure data destruction. The process involves overwriting the volume seven times, ensuring that any data stored on it cannot be recovered.
Choose your security settings and click OK to confirm.
Disk Utility will dismount, erase and remount the desktop volume with a single click of the Delete button.
Erasing or Formatting a Mac Startup Drive Using Disk Utility
Disk Utility can’t erase or format a startup disk because it would be deleting itself in the process. To get around this, use Disk Utility from an external source, such as an OS X installation DVD or recovery volume.
Using the OS X Installation DVD
Put the OS X installation disc into your Mac’s optical drive to begin the installation process.
To restart your Mac, press and hold the C key on your keyboard while the screen is blank after selecting Restart from the Apple menu.
Once the Apple logo appears, release the C key to begin booting from DVD.
Choose English as your primary language and click the arrow.
Access Disk Utility from the Utilities menu to make changes to your computer’s hard drive.
Select the drive from the left side of the Disk Utility window when it opens.
To delete a drive, click the Delete tab in Disk Utility and the name and format of the selected drive will be displayed on the right side of the workspace.
Disk Utility will securely erase the drive from your desktop with a single click of the Delete button.
restart your mac
To return to the Install OS X window, select Exit Disk Utility from the Disk Utility menu.
To exit the OS X Installer, select “Quit OS X Installer” from the menu.
Click the boot disk button to set the disk.
Choose a disk to boot from and press Restart.
Final note
This guide provides step-by-step instructions on how to securely erase external drives using Disk Utility on MacOS. If you have any questions, please reach out for help. Share the love and spread the word!
