Target disk mode - Firewire via thunderbolt.

Discussion in 'iMac' started by ploughguy, May 16, 2016.

  1. ploughguy macrumors newbie

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    Aug 30, 2008
    #1
    I have a 27" iMac that succumbed to the 3TB hard drive failure problem. Apple replaced the disk and I am trying to restore the data from a SuperDuper backup.

    The SuperDuper was written to a USB 3 drive. I bought a LaCie d2 quadra Thunderbolt to recover, except when I got it home I reailsed I had bought the wrong one and it is the triple interface (USB3/Firewire800/eSATA) model. No problems, I think to myself, target mode works with Firewire too, so I use SuperDuper on my laptop to copy the USB3 drive to the Firewire drive. So far so good.

    Then I go to plug the FireWire 800 cable into the back of the iMac and there isn't a socket for it. Duh!

    No problem, though, because I have a Thunderbolt hub with FW800, so I plug that into the iMac, and the LaCie into the hub, and Option-start and Voila! There it is!

    The FW drive is visible as a boot device. I select it and after a few seconds of encouraging thought, I get a kernel panic, "Unable to find driver for this platform".

    It can recognise that it is a boot device, so clearly _something_ can read it.

    So, is there a fix for this? Or do I have to go buy another 3TB drive? (And this time check the small print on the box to ensure it is the right one?)
    R
     
  2. maflynn Moderator

    maflynn

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    #2
    Current 27" iMacs cannot do TDM. What year is your iMac?
     
  3. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #3
    Why isn't USB3 an option?
    I've restored CCC backups to fresh installs over USB3.
    Or how about the $30 Apple TB>FW800?
     
  4. chrfr macrumors 604

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    #4
    I don't see how Target Disk Mode comes into play here. I think you're just trying to boot from an external disk.
    I would suggest starting up the Mac using internet recovery, then restoring your backup once the operating system is reinstalled. That external disk can certainly start up the Mac using either the USB or Firewire interfaces, but it sounds like something isn't backed up properly to allow the startup to happen. Reinstalling the OS using internet recovery should work around this.
     
  5. Significant1 macrumors 6502

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    #5
    Why do you say that?
    I am sure they support thunderbolt target disk mode.
    https://support.apple.com/kb/PH22135?viewlocale=en_US&locale=en_US

    OP. I think you are confusing Target Disk Mode and boot drive. I am pretty sure you can boot from an USB-disk, so it seems needles to go through all these hoops, to get firewire connection.
     
  6. chrfr macrumors 604

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    #6
    27" Retina Macs can do Target Disk Mode, but not Target Display Mode.
     
  7. maflynn Moderator

    maflynn

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    #7
    Ahhh

    My bad :oops:

    Thanks for the correction.
     
  8. ploughguy thread starter macrumors newbie

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    #8
    And here we have the essence of the problem... See? I knew it was a good idea to ask you all.

    I am indeed selecting the boot drive. If this works with USB then my prob is solved.

    My plan is to boot from the backup disk, then start SuperDuper and copy back to the built-in drive.

    To my great surprise, the iMac is a 2012 model - I still think of it as new. It does not have USB 3, but
    USB 2 = USB 3 + time
    so it should work.

    Might try it through the TBolt hub first, though. It has U3 ports so if it works, t'will be quicker.

    Thank you all for your help.
    PG
     
  9. roadkill401 macrumors 6502

    roadkill401

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    #9
    But I thought that the 2012 models came with USB3. Wasn't it the 2011 models that had only USB2.
     
  10. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #10
    Yep
     
  11. ploughguy thread starter macrumors newbie

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    #11
    Correct, apparently. System report shows the proposed boot disk as plugged into a USB 3 port.

    Anyhow, is immaterial - I get the panic when I try to boot from the USB-3 drive too.

    How quickly one transitions from hope to despair. I am starting to feel a sense of nostalgia for the Windows XP days, when at least I could feel good about just giving up and spending three days rebuilding the the whole machine from scratch.

    The machine already has an OS installed by the fixer-fellah. I am trying to recover it back to the way it was. That, I believe, is why I have all this fancy backup technology (a recent SuperDuper, Time machine and Backblaze.)

    However, I have never had to do an OS X restore before, so working out the optimal solution is going to take some time, it seems. The boot-from-SuperDuper-image-then-copy-back solution seemed like it should be the easiest. Ha!
     
  12. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #12
    When the Mac boots on its own, does it go to the setup screen?

    What OS version was copied via SD, and what version was installed on the iMac?
     
  13. ploughguy thread starter macrumors newbie

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    #13
    Amusingly, it does not seem to be possible to create a new posting account on the SuperDuper forums. Has Shirt-Pocket gone out of business?
    --- Post Merged, May 16, 2016 ---
    The backup was last updated a few days before the disk died. "About this Mac" is showing 10.11.4, installed by the repairer. I am certain that the version on the backup disk is the same.
     
  14. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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  15. ploughguy thread starter macrumors newbie

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    #15
    Just tried using an earlier SuperDuper backup on a different drive (a WD MyBook.) This backup was taken week earlier. This time it gets further into the boot process then dies with "Launchd exited."

    Sounds like the kernel is possibly corrupted on the backup.

    Makes me wonder what if the rest of the backup has any value at all.

    Anyone else successfully restored from SuperDuper recently?
    --- Post Merged, May 16, 2016 ---
    The repairer created an Admin account. I have not created any accounts myself because my recovery plan does not need it. Well, did not need it...
     
  16. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #16
    Ok, so on that account, what do you see with the drive plugged in?

    Preferably when connected directly via USB?
     
  17. ploughguy thread starter macrumors newbie

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    #17
    Just noticed that I am ranked as a "macrumors newbie", having created an account in 2008. My, how the internet has grown up...
     
  18. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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  19. ploughguy thread starter macrumors newbie

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    #19
    Both drives are connected directly by USB. The thunderbolt hub is out of the picture.

    Both drives mount successfully and look healthy. From terminal I can see that the USB root has the same stuff that the fusion drive root contains. Plus some extra stuff (developer, Incompatible Software etc.)
     
  20. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #20
    Ok, that's a good sign. And just to confirm, what are you using to restore the backup(s)?
     
  21. ploughguy thread starter macrumors newbie

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    #21
    The restore plan is as follows:
    Boot from SuperDuper backup disk (fails) then use SuperDuper to copy the backup back to the primary drive.
    According to the SD documentation, this is the method.
     
  22. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #22
    Ok. Try an alternate approach.
    Boot the iMac into the temp admin account. Open Migration assistant in Applications/Utilities.

    It will scan the connected drives and should display both as options.

    Select the backup found on the LaCie and see what happens!
     
  23. ploughguy thread starter macrumors newbie

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    #23
    I need a new plan. If I cannot boot from the backup disk, there is a reasonable chance that when I copy it back, I will not be able to boot from it then either. It is possible that the last 4 years of OS updates have fouled something up. Or maybe SuperDuper was not able to copy everything. Whatever the problem is, to get a successful restore, I need to eliminate guesswork.

    So the questions are:
    • Are the non-OS files on the SuperDuper backups reliable?
    • If so, what do I have to copy back from the backup drives to get a working system?
    There are Library trees, password and account information files, applications and a whole mess of non-unixy stuff that make this rather a daunting job.

    I have other backup media, but (a) they are incomplete (I excluded video and virtual machines from Time Machine because it could never keep up.) Plus I don't trust Time Machine to retain its integrity. It runs without complaint for a while then wants me to delete and restore everything. I expect this happens because the bizarre structure that it stores the data in has become corrupted in the past, and it has just discovered the corruption. On both of my machines, disks seem to disconnect without being unmounted (it seems to be a common problem), and I believe this is the kiss of death for Time Machine.

    Has anyone seen a document that details how to restore a full backup without overwriting the OS?
    Russ
     
  24. Mr_Brightside_@ macrumors 68030

    Mr_Brightside_@

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    #24
    Yea, use migration assistant.

    I personally prefer CCC, but have never heard of any method of restoring that involved booting off the source to do it.
    I know it's possible, but just never an option I've seen used.

    My method is always:
    Make TM and or CCC backup and verify it
    Wipe machine and reinstall OS
    boot to welcome screen, migrate files back
    Never caused issues with either backup method
     
  25. ploughguy thread starter macrumors newbie

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    #25
    In my case the source is (allegedly) a bootable copy of the source disk. So (in theory, and according to the SuperDuper documentation) the restore process is to boot from the backup disk and apply the reverse of the backup process. Instead of copying from the computer's disk to the backup disk, you copy from the backup disk back to the computer's disk. You have to boot from the backup disk so it can overwrite the OS files and other config if it needs to.

    Except it didn't work.

    Now that you mention it, though, MigAsst seems to be the totally correct answer. My backup (is believed to) contain the contents of my iMac hard drive shortly before it failed. It is predicting about 5 hours to do the copy back.

    I have not used migration assistant since I last bought a new Mac, which, to my great surprise, seems to have been four years ago. If the damned things didn't last so long, I would have remembered it...

    Thank you for your excellent suggestion.

    I am going to sleep on it. I will report back in the morning.
     

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