How to Boot a Mac in Target Disk Mode

Apr 7, 2010 - 13 Comments

Hard drive icon

Target Disk Mode is a very handy feature available to use with Mac’s that have Thunderbolt or Firewire ports, and it allows you to use one Mac as an external drive on another host machine. This incredibly useful feature makes troubleshooting, installations, large file transfers, and critical backups extremely easy and very fast.

Before beginning, be sure both Mac computers have Firewire or ThunderBolt ports, and that you have a Firewire or Thunderbolt cable. Additionally, each Mac must use the same port, for example, if you’re booting target disk with Thunderbolt, both Macs must use thunderbolt to connect to one another. A converter may work, but it is not recommended.

How to Use Firewire or Thunderbolt Target Disk Mode on Mac

  1. Turn off the ‘target’ Mac (the one who’s drive you want to show up on the host)
  2. Now connect both Mac’s to each other with the Firewire or Thunderbolt cable
  3. Boot the target Mac while holding down the ‘T’ key until you see a Firewire or Thunderbolt icon displayed on screen, this signifies that target disk mode is detected and working
  4. In a few moments, the Mac will bot as usual and the target Mac’s hard drive should appear on the host Mac’s desktop, allowing you to access it like any other external drive
  5. When you are finished, safely eject the target Mac as if it’s any other disk

Once the target Mac has been ejected and disconnected it can be used as normal.

mac target disk mode Target Disk Mode gets frequent use by many power users because it’s ridiculously fast and an excellent method to transfer giant files, but it’s also amazingly useful for troubleshooting problematic Macs and performing some last minute backups of critical files and data if a computer is on its last legs.

While Firewire is no longer shipping on Macs, thankfully Firewire was replaced with Thunderbolt as a high speed data connection on newer machines, which allows this feature to carry on, and that’s so much better than removing the Target disk feature completely.

And no, for the record, you can’t use Target Disk Mode with USB, for now at least, though you can boot from an external USB drive or flash drive if necessary, just not in target mode like this.

What has been your experience with Target Disk Mode on Mac? Do you have any tips or tricks to share? Let us know in the comments.


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Posted by: David Mendez in Mac OS, Tips & Tricks, Troubleshooting


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  1. Bianca Claircidor says:

    Is it safe to reboot the computer after I delete all the files and transfer to the new Mac? I’m having trouble with the disk. My Mac won’t turn on, it will make the chime sound, start loading 1/3 of the way and shut back down. This happens every time I try to turn it on.

  2. Alessio says:

    Thanks for the write-up definitely a handy tool built into Mac’s but it would be nice if it would work with USB rather than having to use Apple’s own thunderbolt connection.

  3. Alessio says:

    Thanks for the tutorial definitely a useful feature but pity it cant use regular usb cable rather than apples own thunderbolt connection.

  4. vexed says:

    My iMac has thunbderbolt. My 20111 mcp has firewire

    This is the reality.

    Now, how do I use Target mode to install OSX on the new SSD in the mbp?

  5. randy johnson says:

    can you do this trick with ethernet cable?

  6. […] a recovery Lion partition, or connecting another Mac (via Firewire or Thunderbolt) and booting into target disk mode. This wasn’t an option for me as I didn’t have a recovery Lion USB device or a Firewire […]

  7. Carsten Legaard says:

    I am really offended why I can’t boot a mini with any of my laptop macs without adding an external keyboard and display (which I do not have at hand).
    Thought Apple was all about friendly UIs …

  8. ADP says:

    Don’t laugh- I have a PowerMac G4 (it’s outlived 4 other Macs! and I just can’t get rid of it yet.) I want to ditch the monitor and have the HD show up on my new iMac. It looks like a monitor has to be connected or it won’t turn on. Any suggestions?

    (They’re connected via firewire cable but it didn’t show up when I restarted my iMac even though it’s plugged in and *should* have power. )

    • arj8138 says:

      Just in case you never found a solution to this did you try to just put a dummy plug in the monitor port?

  9. cintra says:

    What is the most important use of this mode?

  10. Armando says:

    I am really annoyed that you can’t do this with USB

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