Enable Disk Utility's Debug Menu

Disk Utility in OS X Yosemite and earlier has a hidden Debug menu that, when enabled, gives you access to more Disk Utility features than you usually see. While Disk Utility has had a Debug menu for a while, it became even more useful with the advent of OS X Lion.

With OS X Lion, Apple added a Recovery HD partition on the startup drive. You can use it to boot from and run utilities such as Disk Utility, reinstall OS X and access the internet to find solutions to problems you may be having. The Recovery HD partition is hidden, however, and isn't visible from within Disk Utility.

This can lead to problems, including the possibility of having multiple Recovery HD partitions on various drives as you duplicate drives, replace drives, or reinstall OS X. It can also prevent you from moving the Recovery HD partition to a new drive, should you ever need to replace a drive or want to move things around on your drives.

Debug Menu Items

Disk Utilities Debug menu has a selection of capabilities, most of which are designed for developers to use in testing apps that work with the Mac's storage system. Most items are benign, such as List All Disks, or List All Disks with Properties. You can also turn on a Thousand Minute Countdown to change the Console logs for Disk Utility to show 60,000 seconds or one thousand minutes. The purpose is to have a more accurate display of when log events occur.

More interesting for the average Mac user are two commands in the Debug menu:

• Force update of disk list: As the name implies, this causes Disk Utility to update the disks listed in the sidebar. This can be useful when you have attached or removed a disk while Disk Utility is open.
• Show every partition: This displays all partitions on a Mac's drive even if they are meant to be hidden.

If you want to access the OS X Lion and later's Recovery HD partition to create clones or backups, enabling the Debug menu in Disk Utility is the easiest way to see and work with these invisible partitions.

Enable Debug for OS X Yosemite and Earlier

With the release of OS X El Capitan, Apple removed support for Disk Utilities hidden Debug menu. These Terminal commands only work for versions of OS X Yosemite and earlier. To enable the Debug menu in Disk Utility:

1. Quit Disk Utility if it is open.

2. Launch Terminal, located at Applications > Utilities.

3. Enter the following command at the Terminal prompt:

   ​defaults write com.apple.DiskUtility DUDebugMenuEnabled 1​
   
   

4. Press Enter or Return.

5. Close Terminal.

The next time you launch Disk Utility, the Debug menu is available.

Disable the Debug Menu in Disk Utility

If you want to turn the Debug menu off again, perform the following steps:

1. Quit Disk Utility if it is open.

2. Launch Terminal, located at Applications > Utilities.

3. Enter the following command at the Terminal prompt:

   defaults write com.apple.DiskUtility DUDebugMenuEnabled 0
   
   

4. Press Enter or Return.

5. Close Terminal.

Disabling Disk Utilities Debug menu does not reset the commands within the menu to their default state. If you changed any of the settings, you might want to set them back to their original condition before disabling the Debug menu.

That's all there is to enabling or disabling the Disk Utility Debug menu. Go ahead and see what features are available under the Debug menu. You will probably find the Show every partition and Force update of disk list items the most useful.

Use Terminal for OS X El Capitan and Later

In case you are wondering, you can view hidden disk partitions in OS X El Capitan or later; you just need to use the Terminal app instead of the Disk Utility app. To view a complete list of drive partitions do the following:

1. Launch Terminal, located at Applications > Utilities.

2. In the Terminal window, enter the following at the command prompt:

   diskutil list
   
   

3. Then press Enter or Return.

4. Terminal displays all the partitions currently connected to your Mac.