Target Disk Mode | How to Use Target Disk Mode on a Mac

1 Overview of Target Disk Mode on a Mac

If you've used a Mac for any length of time, you've probably discovered a few (but very useful) features and tricks you didn't know about before. One of those is Target Disk Mode. Read on to learn more about it.

What is Target Disk Mode?

Target Disk Mode (TDM), sometimes called Target Disk Mode, is a boot mode designed for Macintosh computers.

Target Disk Mode lets you connect your Mac to the port of any other computer (Mac or PC) and appear as an external drive. You can then format or partition the hard disk in the target Mac as though it were an external drive. Some computers even allow the host to use the internal CD/DVD drive and other internal or external peripheral hardware.

But make sure to back up your data first before formatting or repartitioning the target Mac to avoid losing any information in the process. Or, you can use the Data Recovery Wizard for Mac tool to retrieve lost data even if your Mac won't start up.

Target Disk Mode is very helpful for accessing the contents of a Mac that won't boot up. It's also the preferred way for Apple's Migration Assistant to connect an older Mac to a new one. Migration Assistant supports Ethernet (wired) or Wi-Fi, but Target Disk Mode does not. Neither supports USB, but if one of your Macs lacks FireWire or Thunderbolt ports, you can use a Thunderbolt-to-FireWire, Thunderbolt-to-Gigabit-Ethernet, or USB 3.0-to-Gigabit-Ethernet adapter.

Target Disk Mode for Mac

What can you do in Target Disk Mode? This mode lets you mount your Mac (the target computer) as an external drive on another Mac (the host). Like an external drive, you can view, move, edit, and copy files stored on the target Mac. But Target Disk Mode can also:

• This mode allows you to transfer a large number of files between two Macs.
• You can migrate data from an old Mac to a new one.
• With this mode, you can run Mac First Aid to fix a disk on a Mac that won't start up.
• You can use Target Disk Mode to boot one Mac from another Mac.
• You can delete files when your Mac won't turn on.

Devices that support Target Disk Mode for Mac

The target computer (the one you want to start in TDM) must meet the following requirements:

• A FireWire or Thunderbolt port
• An ATA device on ATA bus 0

The target Mac can be any version, except:

How to Use Target Disk Mode on a Mac

The method varies depending on the type of processor your Mac has. Target Disk Mode works differently on Intel-based Macs than it does on Macs with Apple silicon. But before you boot your Mac into Target Disk Mode, there are a few things you should know.

Preparation for Use

Before you can enter Target Disk Mode on your Mac, there are a few preparations you need to make:

• Two Mac computers. If the target Mac's drive is formatted as APFS, the host Mac should be running macOS High Sierra (version 10.13) or later, such as macOS 13 Ventura, macOS 12 Monterey, and macOS 11 Big Sur.

Boot an Intel Mac into Target Disk Mode

If you have an Intel-based Mac, follow these steps to start your Mac in Target Disk Mode:

Step 1. Connect the two Macs with the appropriate cable, as mentioned in the Preparation section above. For Intel Macs, you should use a Firewire or Thunderbolt cable.

Step 2: In this case, your Mac will boot up. Click on the Apple logo and select “Apple Menu.” Find “System Preferences,” then click “Startup Disk,” and finally, “Target Disk Mode.” Restart your Mac and enter macOS Target Disk Mode.

This image displays a user interface for creating a Startup Disk. In American English, this typically refers to a disk or USB drive used to boot a computer with an operating system or a rescue utility. In Chinese, it's known as "启动盘" (zhǎn dòng pán) or "引导磁盘" (yòu dǎo cí pán). This interface likely allows the user to create a USB or DVD that can initiate the startup of a computer to install an operating system or address issues when normal booting is not possible.

If your Mac won't turn on, you can force it to shut down by holding the power button, then restart it by pressing the T key on your keyboard.

Step 3: If you see the Thunderbolt or FireWire symbol on the screen, your Mac is in Target Disk Mode.

Boot an M1 Mac into Target Disk Mode

There's one thing you need to know – Target Disk Mode is not available on an Apple Silicon Mac. It has been replaced with Share Disk (or Mac Share Mode), a new option on the M1 Mac. Similarly, Target Disk Mode on M1 Mac lets you access your Mac's startup disk from another connected Mac.

Step 1: Connect the Apple chip Mac to the second Mac with an appropriate cable: USB, USB-C, Thunderbolt 3, or Thunderbolt 4 (for 2021 MacBook Pros).

Step 2: Press and hold the power button to turn off your Mac until you see “Loading startup options.”

Step 3: Click “Options” and enter your administrator account password to proceed.

4. Select “Utilities” to access “Shared Disks.” Choose the disk or volume you want to share, then click on “Start Sharing.”

On the second Mac, click Finder, then Locations, and then Network.

On the second Mac, in the Network window, double-click the disk or volume shared by your M1 Mac. Click Connect As, then choose Guest from the window that appears, and click Connect.

How to Use Target Disk Mode to Transfer Files on a Mac

Once your Mac is in Target Disk Mode, you can transfer data quickly between two Macs, since Target Disk Mode supports faster transfer speeds than many external drives.

On Intel-based Macs, go to the desktop and drag the file as you would any external drive.

For an Apple silicon Mac, open Finder and go to the Network in the sidebar. Find the target Mac, then double-click it to mount it. Transfer files as you normally would. When done, eject the disk.

How to Exit Target Disk Mode on a Mac

To stop Target Disk Mode on an Intel Mac, simply shut down the computer and unplug the cable.

On an Apple silicon Mac, you need to eject the target Mac's disk from the host Mac.

If Target Disk Mode fails and you see random errors, press the Power button to turn your Mac off, then unplug the cable.

Quick Fix for Target Disk Mode Not Working Issue

Target Disk Mode might not work in some situations:

- The disk doesn't spin up or is failing. - The disk is formatted for a different computer or operating system. - You're using a damaged or problematic Thunderbolt or FireWire cable. - There might be other issues with the disk.

You can read the following paragraph to learn how to address issues with Target Disk Mode not working correctly.

[Solved] Target Disk Mode Not Working on macOS Ventura/Monterey

Sometimes, you may encounter an issue where Target Disk Mode is not working on your Mac. Before seeking solutions, let's discuss the possible reasons why Target Disk Mode might not be functioning on macOS Ventura/Monterey...

Or you could do some quick tests.

First, make sure both Macs are up to date with the latest version of macOS. You can check for updates by going to System Preferences and selecting Software Update.

Make sure that you're using the right cable, and that both Macs support it.

Third, Target Disk Mode won't work if you have a firmware password set. To disable the firmware password, start your Mac in Recovery Mode, then go to Utilities and choose Startup Security Utility or Firmware Password Utility. Enter your password, and then turn off the firmware password from there. Restart your Mac.

Conclusions

That's all there is to know about Target Disk Mode on a Mac. With the detailed steps in this guide, you can boot an Intel Mac into Target Disk Mode or an Apple Silicon Mac into Recovery Over Network. If Target Disk Mode isn't working on your Mac, try the fixes mentioned above to resolve the issue.