Can't OSX boot from external usb?

Discussion in 'Mac Pro' started by majorp, Aug 17, 2006.

  1. majorp macrumors 6502

    Joined:
    Nov 28, 2005
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    UK !!!
    #1
    I have made a clone of my HD onto my external which has been formatted with GUID but icannot seem to make it boot. whenever i try it just shows the folder with the ? mark in it. i have searched and found nothing helpful. does anybody have any ideas? thanks
     
  2. aaron.lee2006 macrumors 65816

    aaron.lee2006

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    Feb 23, 2006
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    Ontario, Canada
    #2
    I'm no expert, but I think that means an OS X file is corrupt. Try a reinstall first. Maybe its just a glitch.
     
  3. mad jew Moderator emeritus

    mad jew

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    #3
    What sort of Mac is it? Is it PPC or Intel (new)? :)
     
  4. FredClausen macrumors regular

    FredClausen

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    #4
    Probably a corrupt file, but out of curiosity what kind of drive are you trying to boot from? Firewire or USB?

    Edit: I feel stupid. I could have read what kind of drive you had in your title. As gauchogolfer said below, you can't use USB to boot from.
     
  5. gauchogolfer macrumors 603

    gauchogolfer

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    #5
    PPC Macs can boot from external firewire drives, but not usb ones.

    This was one of the reasons people were upset they dropped fw support from new ipods.

    Cheers

    Edit: updated to reflect the discovery that Intel macs can boot from usb drives.
     
  6. Mitthrawnuruodo Moderator emeritus

    Mitthrawnuruodo

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    Bergen, Norway
    #6
    I've made a bootable backup of my internal using SuperDuper! onto my external USB2 drive. That shows up in the StartupDisk.prefPane on my MacBook (though I haven't actually tried booting from it).

    I also used to be able to boot from a USB1 drive with my Pismo... :cool:
     
  7. mad jew Moderator emeritus

    mad jew

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    #7
    I was under the impression that Intel Macs can boot from USB, but I might be wrong. I am wrong so very often these days. :(
     
  8. FredClausen macrumors regular

    FredClausen

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    #8
    No, you can't. I think it has to do with how USB isn't as stable bandwidth wise as FireWire. I'm sure the real explanation is much more technical :rolleyes:
     
  9. Mernak macrumors 6502

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    Apr 9, 2006
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    Kirkland, WA
    #9
    PPC macs cant boot from USB2 but Intel macs work just fine. I have a 250GB external HD that I occasionally boot from.
     
  10. plinden macrumors 68040

    plinden

    Joined:
    Apr 8, 2004
    #10
    I've heard lots of reports that you can boot from USB drives on Intel Macs. I've only done it on Firewire drives, but I have a small USB external drive at home that I'm not using any more. I'll try it out tonight and give a definitive report later.

    Edit: Actually, my external firewire drive here, which has OS X installed on it as a backup, is dual firewire/usb. Give me a few minutes and I'll swap over the cables and reboot.

    Edit2: Boots no problem using USB. It's noticeably slower to boot, I didn't time it though, but it's usable. I'll try the other drive later or at the weekend, whenever I can get time, and try it. One thing to note is, it's not a clone of my drive, it's a separate install of OS X.
     
  11. FredClausen macrumors regular

    FredClausen

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    #11
    Oh?

    *runs off to try booting on my external disk on Macbook*
     
  12. majorp thread starter macrumors 6502

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    Nov 28, 2005
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    UK !!!
    #12
    sorry, its a macbook pro. just don't know why it won't boot. probably currupt. thanks anyway.
     
  13. mad jew Moderator emeritus

    mad jew

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    Location:
    Adelaide, Australia
    #13
    Yeah, most likely corrupt. Maybe try installing OSX freshly onto the external and then booting from it. That way you can work out whether it's a problem with the data or with the enclosure/drive/cable that's preventing you from booting at the moment. :)
     

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