iMacs (Mid-2007) [#3]: More on FireWire target disk mode not working; fixes
We continue to report on significant issues with the newly released Mid-2007 iMacs and FireWire target disk mode. As previously reported, problem reports fall into two groups:
- Other Macs (usually older models) are not recognized at all when connected via FireWire target disk mode to the new iMacs
- Transfers that occur over a FireWire target disk mode connection (particularly system migrations) fail part-way through
Update firmware It appears that in some cases, outdated firmware may be disallowing older Macs from being seen in FireWire target disk mode from the new iMacs.
Apple Knowledge Base article #25773 states:
"[...] You'll need a FireWire cable to connect the two computers together. The Assistant offers to transfer (or "migrate") data from your older computer when you turn on your new computer for the first time. Make sure the older computer's firmware is up-to-date first."
Another Knowledge Base article, #304393, states:
"Some Intel-based Macs can become unresponsive while being used in FireWire target disk mode for long periods of time. [...] This behavior can be corrected with a firmware update to the computer that becomes unresponsive while in Target Disk Mode."
You can generally find firmware updates for your Mac model by going to Apple's download page and searching for your model's name along with the word "firmware."
Verify disk of problematic Mac We've received some reports indicating disk corruption and other drive issues can prevent proper transfer via FireWire target disk mode to the new iMacs. A reader writes:
"I also had a problem using the migration assistant to move data over from my Powerbook G4; the connection would get lost or freeze up part way. Turns out it was my Powerbook - the disk had a couple of minor problems with the volume so I had to fix permissions and then verify/repair the disk first and then the transfer worked like a charm. Possible the iMacs are really touchy with the quality of data coming over?"
Launch Disk Utility, located in /Applications/Utilities and use the Verify button to check for disk errors. If any are found, startup in Safe Mode by restarting your Mac by holding the Shift key, then restart again. Automatic disk checking and repairs are completed when the system is booted in Safe Mode.
Older Macs not supported? Meanwhile, some users are apparently being told by Apple that some older Macs are no longer supported with regard to FireWire target disk mode when used in conjunction with the new iMacs. One reader writes:
"I was told by Apple target mode no longer works with older macs. I have a G4 Quicksilver 933MHz and it failed to work. My new Macbook worked fine."
Feedback? Late-breakers@macfixit.com.
Previous coverage:
- iMacs (Mid-2007) [#2]: FireWire problems: Target disk mode and others (cont.); screen issues
- iMacs (Mid-2007): Problems with FireWire target disk mode; Condensation under glass

It stalled during repeated attempts to use Migration Assistant from a G4 iBook (and failed on a PowerBook, too). Next attempt, it refused to acknowledge that the iBook was connected, and then denied that there was a valid OSX installation on the iBook when it did acknowledge its connection, completely refused to boot on one occasion and wouldn't wake from timed sleep (as opposed to sleep invoked via the keyboard). Deep joy.
We returned it to the reseller on Saturday who insisted on testing it before offering a refund.
It turned out that the iMac had 'problems with both the hard disk and RAM'. Unfortunately, this info came to me secondhand so I cannot be more specific, but could manufacturing defects be causing/adding to these widespread issues?
According to Apple I was to update the firmware on his PowerMac G4 450MHz (Gigabit Ethernet) unit but that did not help. Only after reading a workaround on MacFixIt which was to connect a firewire device BETWEEN the old and new units, in this case a LaCie CD-RW, did the target disk show up on the desktop of the new Mac and allow the transfer!
THANKS MACFIXIT!!!
- by stevenjdesign September 25, 2007 7:27 PM PDT
- I had just purchased a 2.8ghz iMac 24" and was trying to migrate from a 700mhz eMac but it wouldn't see the target disk via the firewire cable I was using (from an external hard drive).
- Like this Reply to this comment
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(3 Comments)I read the comment that lizmac made about adding an external firewire device and a second cable so that the external device was in the middle and tried that and it worked perfectly!
I can't believe how easy it was to migrate with the firewire cable and be up and running again.
Thanks to all who post their fixes to problems.
Regards Steve J