Blog Post

Mac 101: Target Disk Mode

Apple’s Target Disk Mode is an essential tool built-in to every Mac. It has become irrelevant simply because switchers today aren’t aware that it’s even there.

Apple’s primary document explaining Target Disk Mode covers nearly every Firewire equipped Mac beginning with the slot-loading iMac back in the PowerPC G3 days of 1999. Today, there are over 150 docs on Apple’s Knowledge Base that incorporate the use of Target Disk Mode in troubleshooting.

Apple obviously notices the trend that its customers are not using this powerful tool any longer. Two of Apple’s current Macs don’t even include Firewire (MacBook and MacBook Air) and this technology simply won’t work over USB.

Why would someone need this anyway? Let’s say you start up your Mac and nothing happens. There’s no login window and no boot screen at all. You hear the hard drive whirling around but that’s it. After inserting the Mac OS X disk, you can see the HDD is mounted and you only have two options. The first is to erase the disk for an OS reinstall and the other is to scan the drive for errors. Well, an error check doesn’t help and now you’re stuck with a non-booting Mac and a few important files that weren’t backed up.

On most modern Macs, pulling out the HDD and putting it in a 2.5″ external HDD enclosure will do just fine but you need those files now. All you must do is plug in a Firewire cable and connect the other end to another Mac with Firewire. Oh yeah, I forgot to mention that you must be lucky enough to have a spare Mac with Firewire laying around.

Once the two computers are connected, simply boot up the healthy Mac login. On the other computer, hold down the “T” key and hit the power button. With a little luck, the previously non-booting machine’s HDD will appear on your functioning Mac’s desktop. Voilà, you can now successfully copy those files to your working Mac and run the dead machine to an Apple Store.

Target Disk Mode is a powerful utility that can really help out in a bind. What other users for it have you found?

10 Responses to “Mac 101: Target Disk Mode”

  1. I just used it to run a full system restore from time machine. Normally you can just use the install disk, but the optical drive was reading it. SO I had to target mode another mac to access its good optical drive, pop the install disk in, run the restore from time machine utility, pick a date and restore.

  2. Even if they get rid of target disk mode you can still transfer files easily using ethernet. Just connect the two machines together using an ethernet cable and turn file sharing on (remember to turn it off after you finish!).

    Am copying 35.5GB of media files over from my old MacBook and it’s taking 10 mins.

  3. Alhasib

    I use Target disk mode often at work and it is a big time saver. It is very useful when a fellow coworker gets a new mac. I can quickly copy huge folders (ie: 50GB+) with the entire collection of video and multimedia files they need for presentations.

  4. You can also use Target mode to install software on a mac with a dead optical drive. I have reinstalled the operating system this way. The optical drive of a Mac connected in Target Disc Mode is available (or drive connected to it). In the start-up control panel you can select any valid Mac OS to boot from the Mac connected via Target Disk Mode

  5. Osmodious

    It has been SO valuable when I upgrade…I haven’t had to reinstall the OS or even a single app (including MS Office) since my first PowerBook in 2001! I just boot up the new machine, connect the old one in Target mode when prompted, and voila…everything is sucked over onto the new machine. When it finally finishes booting, it looks and works like the old machine…except faster.

    I will be VERY unhappy if that capability goes away. VERY unhappy.

  6. alphacheck

    Also great if you have a mac with a hiccup. You can mount the disk from another mac and run disk tools, or virus software if needed.

    Target Disk Mode is a wicked fast way to move files without having to boot up.

    Transitioning to a new mac? Target Disk Mode, and migration tool.

    Want to use your macbook drive without dealing with networking on your iMac screen? Target disk mode, and the MacBook will appear as a start-up option on the iMac.

    I’m sure there’s more. I’ve used it for lots of stuff.