How to use FireWire target disk mode
Important: Unplug all other FireWire devices from both computers prior to using FireWire target disk mode. Do not plug in any FireWire devices until after you have disconnected the two computers from each other, or have stopped using target disk mode.
Tip: If you will be transferring FileVault-protected home directories (Mac OS X 10.3 or later only), log in as the FileVault-protected user and temporarily turn off FileVault. After transferring home directory contents to the target computer, enable FileVault protection again if desired.
To use FireWire target disk mode
Make sure that the target computer is turned off. If you are using a PowerBook or iBook as the target computer, you should also plug in its AC power adapter.
Use a FireWire cable (6-pin to 6-pin) to connect the target computer to a host computer. The host computer does not need to be turned off.
Start up the target computer and immediately press and hold down the T key until the FireWire icon appears. The hard disk of the target computer should become available to the host computer and will likely appear on desktop. (If the target computer is running Mac OS X 10.4 Tiger, you can also open System Preferences, choose Startup Disk, and click Target Disk Mode. Then restart the computer and it will start up in Target Disk Mode.)
When you are finished copying files, drag the target computer's hard disk icon to the Trash or select Put Away from the File menu (Mac OS 9) or Eject from the File menu (Mac OS X).
Press the target computer's power button to turn it off.
Unplug the FireWire cable.
If the target computer's hard disk does not become available to the host computer, check the cable connections and restart the host computer.
Find out about "FireWire Ports and Specifications".
Tip: FireWire Target Disk Mode works on internal ATA drives only. Target Disk Mode only connects to the master ATA drive on the Ultra ATA bus. It will not connect to Slave ATA, ATAPI or SCSI drives.
Using Target Disk Mode with Intel-based Macs
If you attempt to mount an Intel-based Mac in Target Disk Mode on a Macintosh running Mac OS X 10.3.9 or earlier, you'll see an alert message. For more information, see article 303118, "Intel-based Macs: "You have inserted a disk containing no volumes that Mac OS X can read" alert message".