Target disk mode issue

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Level 1

8 points

Target disk mode issue

I am trying to access my mid 2012 Macbook Pro (runs High Sierra) with my 2010 Macbook Pro 17, running Yosemite via thunderbolt cable. The drive I am trying to access has an issue preventing Mac OS from booting up, but passes all disk utility tests in Mac diagnostics and repair says all is good. I am unable to get it to show up on the older Mac. Target disk mode appears to be running on the machine I am trying to access (target icons moving around the screen). Anyone have suggestions? All I can find is use the appropriate cable. Info seems all over the place and is unhelpful.

Posted on Mar 5, 2018 2:58 PM

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Answer 1

Kappy

Level 10

361,741 points

Mar 5, 2018 3:13 PM in response to Daysef

See Target Disk Mode article. Do both machines have Firewire ports and/or Thunderbolt 2.0 ports? You may have a problem with the Yosemite machine until it is upgraded to High Sierra due to changes made since Yosemite to sharing.

The fact that the remote disk in question has passed diagnostic tests does not mean it hasn't malfunctioned. Neither AHT nor First Aid correctly identifies malfunctioning disks. This is hinted at by the fact that the disk will not mount in TDM. I would remove the drive and put it in an external USB enclosure. Then try accessing the drive by connecting it to a USB port on the other MBP.

Unless you need files on the 2010 MBP I would reformat the drive. If you are not able to reformat the drive then the drive is bad.

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Answer 2

Daysef Author

Level 1

8 points

Mar 5, 2018 3:46 PM in response to Kappy

I have files on the newer computer I am trying to recover. I hesitate to upgrade the OS on the older computer as it slowed the newer one and pushed the 4 gig of memory. Obviously, the drive has malfunctioned in some way-and waited until I tried to do a memory upgrade. I have reinstalled High Sierra on the drive, so it appears to accept the reinstall. Something has happened to prevent a full boot up (progress bar fills completely-after about 20-30 minutes-then appears to completely stall). My backup is out of date (stupid, I know) and I have photos and docs I want to save. This is the first time I have encountered this type of issue with a Mac (25 years of Mac use, 37 years of computer use) and I am disappointed that this useful feature is not so useful after all when I really need it. I'm still a Mac fan, just a very perturbed one at the moment.

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Answer 3

Kappy

Level 10

361,741 points

Mar 5, 2018 3:50 PM in response to Daysef

I would say you are pretty lucky that this is the first time this has happened to you in 37 years. I started with computers nearly 43 years ago. With Macs since 1988. To me, this isn't a new problem. But it isn't a frequent one. You were due. 😁

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Answer 4

Daysef Author

Level 1

8 points

Mar 5, 2018 7:07 PM in response to Kappy

Overdue, most likely. Caught me with my back-up pants down... Thanks for the reply. It's much appreciated.

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Target disk mode issue

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