Today we’ll discuss what happened to the Secure Erase Free Space feature in Disk Utility on your Mac and how to securely wipe the free space on your Mac’s HDD without that feature.
What Happened to Secure Erase Free Space in macOS?
The Secure Erase Free Space feature in Disk Utility on your Mac added a layer of privacy and security to file deletion. The feature allowed you to overwrite the free space on a drive to prevent deleted files from being recovered.
Modern versions of macOS, and later versions of OS X, like El Capitan, don’t include the Secure Erase Free Space feature in Disk Utility. Because most Macs now come with Solid State Drives (SSDs) instead of regular hard disks, Apple feels there is no need for the feature. When you erase files normally on an SSD, it’s difficult to recover that data.
Apple explained that you don’t need to securely erase your Mac’s SSD in their
online knowledgebase:
With an SSD drive, Secure Erase and Erasing Free Space are not available in Disk Utility. These options are not needed for an SSD drive because a standard erase makes it difficult to recover data from an SSD.
Use FileVault to Keep Your Data Safe
Whether you have an SSD or an HDD, you should
use FileVault to protect your data. FileVault encrypts your whole drive so all your files are protected. You need a password to access anything on the drive. Without it, your data remains encrypted and safe from unauthorized access
.
Securely Wipe the Free Space on Your Mac Using the Command Line
Before wiping the free space on your Mac using the command line,
back up your data.
Once you’ve backed up your data, open the Terminal app from the
Applications > Utilitiesfolder.
Then, type the following command at the prompt and press
Enter.
diskutil secureErase freespace 4 /Volumes/Macintosh\ HD
Make sure you include “freespace” in the command. This indicates you are only erasing the free space on the drive and not the entire drive.
The number “4” indicates the wipe level performed on the drive’s free space. You can use “4” for the wipe level, or select a different option from the following list:
- 0 – Single-pass zero-fill erase.
- 1 – Single-pass random-fill erase.
- 2 – US DoD 7-pass secure erase.
- 3 – Gutmann algorithm 35-pass secure erase.
- 4 – US DoE algorithm 3-pass secure erase.
The more passes you do when wiping the free space, the longer the process takes.
Replace “Macintosh\ HD” with the name of the volume you want to wipe the free space on. If the name of the volume contains a space, type a backslash in front of the space, like we did in our command. Make sure you include “/Volumes/” before the name of the volume.
