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July 30, 2006 7:30 PM

Data recovery in target disk mode: what are the pitfalls?

A friend of mine has a G4 iBook that is dead. He has been told by a computer repair person (non-Apple) that his logic board is hosed. He'd like to save his old iTunes and iPhoto libraries to his new MacBook Pro. I told him about Target Disk Mode and offered to perform the transfer for him, but he's wary and is afraid of losing some of his photos forever. Is target disk mode fairly safe, assuming there is no damage to the HD on his old iBook? Also, is target mode even possible if the logic board is hosed? What if the power supply on the iBook is dead? Is there any thing I should beware of?

posted by mds35 to computers & internet (8 comments total)

target disc mode can't happen without the logic board, since it runs through the firewire ports. same with the power supply - the drive has to spin up somehow. his best bet is to pick up a 2.5" enclosure like this, pull the drive from the iBook, and slap it in the enclosure. the bonus for doing it this way is that once his files are recovered he has a nice, pocket-sized portable drive.
posted by casconed at 7:37 PM on July 30, 2006

I know nothing about this particular issue, but someone assured me once that it was very dangerous to do Target Mode with a laptop running on batteries, not on mains power.

He assured me you could get into huge problems. He generally didn't know what the hell he was talking about, but worth mentioning. Perhaps someone can confirm/deny?
posted by AmbroseChapel at 8:06 PM on July 30, 2006

I use my PB G4 in target disc mode without mains power all the time. i think you could run into trouble if the battery ran out and the disc didn't unmount properly, but i believe that this risk is mostly mitigated by OS X using a journaled filesystem (which is the default now). worst-case scenario, in my mind, is that you might have a file open from the offending laptop, said laptop runs out of juice, disc "disappears" and you have to save the file elsewhere.
posted by casconed at 8:24 PM on July 30, 2006

i had a firewire disk get absolutely hammered by power loss while the disk was online. 200+ uncorrectable bad sectors. i'd be very careful running the ibook on batteries alone in target mode.

taking the disk out of an ibook is much easier said than done, but its probably the safest route here.
posted by joeblough at 9:05 PM on July 30, 2006

Plug it in just to be safe. Or at the very least see if you can fully charge the batteries first. Target disk mode should not "erase" any files. It's the same as booting up the iBook.
posted by lunarboy at 10:09 PM on July 30, 2006

Apparently it depends on how hosed that logic board is, because hanks to the iBook G3 logic board defect I've repeatedly had to resort to Target Disk Mode to retrive data after a logic board failure (these were each confirmed and replaced by Apple). This method has always worked so far. *knock on wood*

If he's really worried about data loss, best not to touch the iBook since he'll be too nervous and any damage you find might be attributed to your activity no matter what. Refer him to Drive Savers instead. He'll pay a fortune to get his data out of there, but by golly they'll recover every sector that can still somehow be read. Either that, or once he hears their quote he'll feel a lot better about letting you take a shot with Target Disk Mode.
posted by nakedcodemonkey at 10:28 PM on July 30, 2006

Target disk mode may not even be a possibility in this case - hosed logic boards can prevent the machine from booting, or from running off AC power - in either case, you'll probably be out of luck. The only foolproof method to getting all of the existing data on that HD off of that HD is to use the "remove hard drive, transfer to external enclosure" method.

Please refer to the excellent instructions at ifixit or sterpin.net for details.
posted by sluggo at 8:40 AM on July 31, 2006

Update:

I happened to be at his house the other day and had my firewire cable in my car. I connected the iBook to his MacBook Pro and crossed my fingers. The target mode file transfer worked very well. We managed to get all of his data onto the new machine. The iBook started up fine but the screen was dead and there was a vague scent of smoldering plastic coming from it.
posted by mds35 at 11:30 AM on December 27, 2006