Can't boot from external Lion drive on Retina Macbook

Discussion in 'OS X Mountain Lion (10.8)' started by Vandal., Apr 20, 2013.

  1. macrumors member

    Vandal.

    #1
    Hey guys,

    I like to create clones of my startup disk when transitioning between machines or systems to be able to boot from these if anything goes wrong, I forgot stuff, sell the old machine etc. etc.. This always worked nicely, I have an external drive with two partitions, one Snow Leopard, one Lion that I can boot from with my old macs running Lion.

    Now I just got a new Retina Macbook and 10.8.3 doesn't let me boot from either, the Lion partition just gives me the prohibitory sign.

    I'm aware that the Retina Macbooks won't run Snow Leopard but from what I read they should let me boot from systems as "old" as 10.7.4. Is there something I am missing here?

    Any help would be greatly appreciated.

    Thanks,
    V
     
  2. macrumors P6

    Intell

    #2
    They had a custom build of 10.7.4. You need to have at least 10.7.5 on the external to be able to boot from it.
     
  3. macrumors 603

    justperry

    #3
    You can actually update to 10.7.5 on the external when you connect it to the rMBP, you just have to select the disk when doing the update.
    Provided you download 10.7.5 manually.
    Well, it should work, you'll never know with these newer OS"s.
     
  4. macrumors member

    Vandal.

    #4
    The external is actually 10.7.5 already but it still won't boot from it. I guess I could just update the machine it was cloned from to ML and then clone it again. Might loose a few applications to incompatibility but I'd still have the old system...
     
  5. macrumors member

    Vandal.

    #5
    So now I updated the Lion partition on the external to Mountain Lion and it still won't boot. I'm getting the prohibitory sign again.
     

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