What is a startup disk on MacBook

What is Target Disk Mode? How and when do you use it on your Mac?

Every Mac can use a variety of startup modes and startup key combinations. A quick guide to macOS startup modes and startup key combinations A quick guide to macOS startup modes and startup key combinations Your Mac has several startup key combinations that unlock different startup modes. Troubleshooting. Here's a guide to what they all do. Continue reading . One of them is Target Disk Mode, which essentially turns your Mac into an external hard drive.

By connecting two Macs together this way, you can quickly transfer files, migrate your data to a new Mac, or access your startup disk if macOS refuses to boot. While regular backups are always important, Target Disk mode provides additional security in the event of a disaster.

Let's take a closer look at Target Disk mode and the different ways you can use it to your advantage.

What is Target Disk Mode?

Target Disk mode is a startup mode that lets you browse and transfer files from an internal Mac drive without starting macOS. Volumes are provisioned virtually and instantly, and using a cable means transfers are significantly faster than comparable wireless methods.

You cannot use the target Mac while it is in Target Disk Mode. Your Mac essentially becomes an enclosure for your internal drive. To use your Mac again, you'll need to disconnect and restart as usual.

Target Disk Mode was first introduced with the PowerBook 100 in 1991 and has since been included in most Mac models. Exceptions are the iMac for tablet charging, Power Macintosh G3 and G4, models of the iBook G3 without FireWire, the first MacBook Air (2008-2009) and the old unibody MacBook.

What You Need to Use Target Disk Mode

You need two compatible Mac computers to use Target Disk mode, each with a FireWire or Thunderbolt interface. You will also need a cable and any necessary adapters (such as Thunderbolt to FireWire or Thunderbolt 2 to Thunderbolt 3).

You can't just use old USB Type-A ports (not even USB 3.0), but old Thunderbolt and FireWire connections are compatible with the latest standards. Note that Thunderbolt cables aren't cheap. Apple is currently asking for $ 39 for a 2.5 meter Thunderbolt 3 cable.

If you're using a newer Mac, e.g. For example, if you have a post-2017 MacBook Pro or a slim iMac, you should use a Thunderbolt 3 cable, not a USB cable (or Apple's charger). We have compiled a guide to help you understand the differences between USB Type-C and Thunderbolt cables to understand USB-C and Thunderbolt cables and connectors on your MacBook What are USB-C and Thunderbolt and how do these cables affect your MacBook? Everything you need to know about your MacBook ports is here. Continue reading .

How to Use Target Disk Mode on Mac

When you use Target Disk Mode, each Mac takes on a different role:

  • aim: This is the Mac that contains the hard drive you want to access. There is nothing you can do with this Mac as it will stay in Target Disk Mode for the duration of the process.
  • host: This is the Mac that will access the drive. It will start up in macOS as usual so you can transfer files.

1. Connect your two machines

Take your cable and connect both computers using the appropriate Thunderbolt or FireWire ports. Connect any adapters you need for older machines. If you're doing this on a MacBook, make sure it has enough power for the duration of the transfer, or plug it into a power source.

2. Start the Target Mac in Target Disk Mode

You can do this in two ways:

  • Shut down your target Mac, press the power button, then press T and hold it while your Mac boots. You can let go when you see a Thunderbolt or FireWire icon on the screen.
  • If your target Mac is already running, go to System Settings> Startup Disk and click on Target disk mode to force a restart in Target Disk Mode. You don't have to hold down any buttons here.

3. Decrypt and access your drive

Wait for macOS to recognize your target Mac's drive. If your destination drive is encrypted with FileVault What is Mac OS X FileVault and how do I use it? What is Mac OS X FileVault and how do I use it? Only by manually encrypting the files on your hard drive can you really protect your files. This is where FileVault from Mac OS X comes in. For more information, when you start the target Mac you will need to enter your password. Wait for the drive to be decrypted. Then it should appear like any other external drive.

4. Copy, transfer and split

Use the Finder to browse, copy files to and from the hard drive, and then safely eject the hard drive. You can do this by dragging your target Mac's drive icon over the icon rubbish or by right-clicking the drive and selecting Eject.

On your target Mac, press the power Button to turn off the machine. You can now restart your computer as normal if you want.

When to use Target Disk Mode on Mac

Now that you know how to use the target disk mode, there are a few applications that you should become familiar with for this boot mode.

Fast wired file transfers

If you are used to transferring files between computers that use intermediate media such as an external hard drive, you can use Target Disk mode instead. You don't need to copy from your Mac to a USB volume, but from your USB volume to your destination. Just switch from Mac to Mac.

This is especially useful for large files like videos, media libraries, disk images, etc. A wired transfer over Thunderbolt is much faster than a similar wireless transfer where the notoriously flawed AirDrop AirDrop doesn't work? Troubleshoot file transfer problems AirDrop not working? How to troubleshoot file transfer issues after AirDrop issues? We can walk you step by step through all of the options available. Continue reading .

Transferring data with the macOS Migration Assistant

If you've bought a new Mac, you'll want to transfer your old data to it. There is no faster way than using Target Disk Mode. In this scenario, your new Mac (from which you are transferring data) to) is the host and your old Mac (which you want to get data on.) of) is the goal.

Connect the target and the host, start the target as usual in Target Disk Mode and then start the host Migration Assistant under Utilities. Choose From another Mac, PC, Time Machine backup, or other hard drive then select From a Mac, a Time Machine backup, or a startup disk.

When prompted, select the destination Mac drive and click Continue to start the transfer process.

Recover files when macOS won't start

Operating system failures happen to the best of us. Is it the result of a botched macOS update to macOS Sierra? Fix common Mac upgrade issues. MacOS Sierra installation problems? Fix common Mac upgrade issues. How do you recognize a frozen installation? What if my Mac ran out of space during installation? And how do you fix the problem when you can no longer access your computer normally? For more info or a shady kernel extension preventing the system from booting, connect your problematic Mac to Target Disk mode and just take a breath.

Once you've mounted your Mac's drive, you'll be able to copy those important files, media libraries, and working documents that you forgot to back up. If you have enough space, you can pack all of your things / User / Folder!

Run a target Mac's operating system on the host

What if you have a MacBook with a broken screen or a shady keyboard? Target Disk Mode allows you to use a host Mac to start a target's operating system. This will restore access to the damaged Mac so you can restore files, erase the hard drive, and perform other tasks.

Connect the two machines as usual and start your defective (target) Mac in target disk mode. Now restart the host computer and open the start manager by holding down the button possibility how your host Mac boots. You will see the target Mac drive appear in the Start menu. Select it and your host will boot your target's drive as normal.

You will need to know the FileVault password to decrypt the drive if you are using it. From here, you can restore files, run applications, and prepare your computer for repair.

Limitations of Target Disk Mode on Mac

Target Disk mode offers real security and some everyday benefits - all you have to do is remember to use it! However, if you really did trash your target Mac, this may not help fix your problems.

This is because Target Disk Mode only works when your drive is operational. If you have a bad drive External hard drive not showing up on Mac? How To Fix External Hard Drive Not Showing Up On Mac? How to Fix External hard drive not showing up on your Mac? Here is a troubleshooting guide to get your external hard drive or flash drive working again. Read More Damage to Thunderbolt and FireWire ports also make this difficult, and problems with the logic board that could prevent these ports from operating normally.

Learn More About: Boot Failures, Data Recovery, File Management, Mac Tricks, Thunderbolt.