Wiping a Mac Drive: A Comprehensive Guide

Mac computers come equipped with a convenient built-in tool called Disk Utility for managing disks. With this application, you can easily rename, format, and wipe connected drives, while also creating and restoring backup images. Whether it's external storage or your Mac's internal drive, Disk Utility is an excellent choice for securely wiping drives. This article for Cybersecurity Awareness Week is sponsored by Incogni.

Deleted files from a drive can potentially be recovered using traditional methods, such as emptying the trash. However, this possibility depends on various factors. In the case of mechanical hard drives, deleted files are merely marked as deleted and can be overwritten in the future. On the other hand, solid state drives (SSDs) typically use TRIM to delete files immediately. However, this feature does not apply to most external storage devices like flash drives, making deleted files still easily recoverable.

To ensure that deleted files cannot be recovered, you can "wipe" a drive by writing zeroes or other random data to every sector. This process makes it nearly impossible to retrieve the previous data. Although physically destroying the drive is the only foolproof method of permanently deleting data, using the wipe function in Disk Utility or similar software is usually sufficient unless your flash drive contains extremely sensitive information like nuclear launch codes.

How to Wipe an External Drive

To begin, launch Disk Utility on your Mac. You can locate it using Spotlight (by clicking the search button in the menu bar or using the Command+Spacebar keyboard shortcut) or the search bar in Launchpad. To access Disk Utility, navigate to Applications > Utilities > Disk Utility in the Finder.

To begin, ensure that the drive you wish to erase is connected. If it is not yet connected, please do so now. In addition, make sure that the sidebar is visible in order to view all of your connected drives. If the sidebar is currently hidden, click the View button and choose "Show sidebar."

You should choose the drive in Disk Utility, rather than one of the partitions on the drive. The drive is positioned in the sidebar above any partitions as the top-level item. For instance, in the screenshot provided below, "Patriot Memory Media" represents the drive (and is selected), while "PATRIOT" is a FAT32 partition on the drive. If you wipe a partition instead of the entire drive, there is a possibility that not all the data will be erased.

Click on the Erase button located at the top of the window once you have selected the drive. Disk Utility will then present a popup menu where you can specify the desired drive name, file system/format, and the partition scheme. It is important to note that the available options will differ based on the type and size of the drive.

To ensure compatibility with non-Apple platforms, set the scheme to Master Boot Record or GUID (if available) and the format to MS-DOS FAT or exFAT (if available). Please note that exFAT may be necessary for larger drives or files exceeding 4GB, but not all devices support it. It is important to remember that Mac OS Extended format can only be read and written by Mac computers.

For secure wiping of the drive to prevent file recovery, click the "Security Options" button in the popup. This will display various wipe options, ranging from not zeroing out the drive (which may allow recovery tools to access erased data) to writing over the entire drive seven times for maximum security. Each wipe option increases the duration of the process, especially for mechanical disks and flash drives. In most cases, the second option (2x write over) is sufficient.

When you're ready, click the Erase button to start the process. After that, you'll have a clean drive!

How to Wipe Your Mac's Internal Drive

To securely sell or pass on your Mac to another person, it is important to perform a complete factory reset on your device. This procedure not only erases all data on the internal storage but also reinstalls the macOS from the internet, making it ready for the subsequent setup process.

We have a dedicated guide for how to factory reset any Mac, so you can follow those instructions to wipe your Mac and set it up fresh.