Target mode with thunderbolt not working

Discussion in 'Mac Basics and Help' started by Jess__1990, Nov 1, 2017.

  1. Jess__1990 macrumors newbie

    Nov 1, 2017
    hello! I am attempting to connect 2 MacBook pros via a thunderbolt cable, in order to run a data recovery on one of the MacBooks. Ie: a host computer (mine) the target mode computer (my sister’s MacBook) with the intention to load hers onto mine as an external HD to scan using third party software for her erased hardrive- most consequently “photos library”.

    What I have done so far: plugged both machines together with the thunderbolt cable, AC power on for both, boot up target disk (sister’s) holding T down. Result: her screen has 2 icons on it: thunderbolt and target disk mode and HD does NOT show in my my MacBook.

    For a brief period it did come up on my desktop but then disappeared. I noted that during that period, only the thunderbolt icon was present on my sister’s MacBook.

    Any help would be appreciated! Apologies for the convoluted explanation of my issue.
  2. hobowankenobi macrumors 6502a

    Aug 27, 2015
    on the land line mr. smith.
    That's a tuff one.

    It could be: bad connection (bad/finicky TB ports, and/or cable). If you have another TB cable, you should try it. You can also try the second TB port on each machine.

    If it is not the TB connection (port-cable-port), it is possible that the target machine has a failing or failed HD. Just like any external HD, if it is not fully functional, or formatted in Mac-friendly format (we know yours is because it is/was a boot drive), it won't mount...or stay mounted. Any chance the drive itself is damaged or failing?

    Beyond that, a reboot never hurts, and you could try a PRAM reset...but that should not be required.

    FYI, the behavior sounds correct: if a machine has multiple ports that support TDM, such as TB and FW, you get 2 icons. When one is used (a connection is made), that icon stays. You made a TB connection, and the TB icon remained.

    Sounds like this machine may also have a FW800 port. If so...and your machine has a FW800 port too, you could try a FW800 cable to rule out the TB ports and cable.
  3. Jess__1990 thread starter macrumors newbie

    Nov 1, 2017
    Thanks Hobo. Definitely helpful ideas. It is possible that the HD is failing, as the whole point of me erasing/reloading the system was to try and get it working faster for her but when wiped, it still ran a little slow, the only couple of times I’ve turned it on.

    What is a PRAM RESET?

    Roger, re the symbols; that makes sense then.

    I’ll check out the FW situation too. Limited resources in my little country town but the local newspaper may have a cord!

    Any other ideas of how I could scan the drive without loading recovery software directly onto my machine? (Which I’m guessing would be a bad idea?)
  4. organicCPU macrumors 6502a


    Aug 8, 2016
    If a drive is failing, prevent any unneeded interaction with it. Switch it off.
    If a drive is failing, it's normal that it will unmount. Good chance that the TB cable is o.k.
    If you really need the data, take the Mac to a professional recovery service.

    If you can live with data loss, if it's a HDD not encrypted by File Vault and if you want to practice recovery, you'll need to prepare yourself a bit. IMHO, in this post there are some interesting advices about recovery. To summarise some cornerstones:

    1.) Learn how to switch off anything on your host machine that impacts the recovery target (Time Machine, Spotlight, etc.)
    2.) Learn how you can handle the disk arbitration daemon on your host that tries to mount the recovery target (e.g. with Disk-Arbitrator) as you don't want it to do this.
    3.) Learn how to use and install a tool on your host to make a block copy of the recovery target (like ddrescue). You'll probably need an extra drive that is large enough. That means that you don't need to install software on the failing Mac.
    4.) Use Target Disk Mode like you tried or put the failing drive into an eSATA or Thunderbolt enclosure. Switch the target on and do recovery with patience (a couple of days).

    After that the hard part begins. Try to get some data out of the block copy disk image file. Better work on a copy of it. How good your chances are, getting a complete photo library out of your rescue with an erased (destroyed) b-tree you might be able to imagine. Maybe you can manage to restore that file catalog with some tool. If not, with some luck and lots of hours of work you might be able to recover single files of the photos library's images that meanwhile changed their names (they're gone with your file index).
  5. Jess__1990 thread starter macrumors newbie

    Nov 1, 2017
    Thanks organic CPU. I’ve recovered a lot of single photos (perhaps all of them, I’m not sure) off the external HD which I also managed to wipe. I’m beginning to realise after reading and understanding some of what you ha d said that this is probably the best I am going to get and to recover a whole intact library is well, dreamin’! Cheers for the help!
  6. Fishrrman macrumors P6


    Feb 20, 2009

    Tell us more about your sister's MacBook.
    Is it an older one (white) with a removable hard drive?
    Or is it one of the newer ones with the "blade" drive?

    I might be mistaken, but even with the blade drive models you might be able to take the back off, take the drive out, and mount it into an external (specialized) enclosure to access it...
  7. Mr_Brightside_@ macrumors 68040


    Sep 23, 2005
    You are not mistaken on the last point. Everything up until TB models (including non-TB current 13" Pros) have a removable HD/SSD.
  8. Jess__1990 thread starter macrumors newbie

    Nov 1, 2017
    It was bought new in dec 2012 and is a MacBook Pro. I don’t know the exact model but I would say it would be the base model.

    It has shown up on my desktop today so I am scanning to see what will happen!
  9. hobowankenobi macrumors 6502a

    Aug 27, 2015
    on the land line mr. smith.
    If you suspect a failing HD, get what is most important first, and work your way down. It could limp along for weeks or months...or die at any moment. No way to tell, so expect the worst and recover accordingly.

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8 November 1, 2017