Booting from External HDD

Discussion in 'Mac Basics and Help' started by nambuccaheadsau, Apr 18, 2008.

  1. nambuccaheadsau macrumors 6502

    nambuccaheadsau

    Joined:
    Oct 19, 2007
    Location:
    Nambucca Heads Australia
    #1
    Have set up external drive using firewire and SuperDuper copying all files to the external disc. On reboot holding down the Option key brings up a window with three icons/buttons.

    Left icon shows arrow in 3/4 round circle, centre Leopard HD with a light blue cross and right an arrow pointing to the right. Assuming Leopard HD and X indicates not available, but which icon/button continues the boot from the external drive please?
     
  2. merl1n macrumors 65816

    merl1n

    Joined:
    Mar 30, 2008
    Location:
    New Jersey, USA
    #2
    What type of Mac do you have, a PPC or Intel?

    Then when you formatted the drive, what partition map did you use? PPC requires the Apple Partition Map. Intel requires the GUID mapping. Otherwise the drive will not be bootable and not show up at the boot loader screen like you describe.
     
  3. windowpain macrumors 6502a

    Joined:
    Apr 19, 2008
    Location:
    Japan
    #3
    In system preferences there is an option to choose your startup disk.
    It should tell you where the volume is located (in this case on your external HD) and you can choose the correct one.
     
  4. nambuccaheadsau thread starter macrumors 6502

    nambuccaheadsau

    Joined:
    Oct 19, 2007
    Location:
    Nambucca Heads Australia
    #4
    1. Does not appear in System Preferences but on the Desktop.

    2. PPC no partition the disk was formatted through Disk Utility HFS+ (Journaled). Should it be partitioned for backing up OS?
     
  5. merl1n macrumors 65816

    merl1n

    Joined:
    Mar 30, 2008
    Location:
    New Jersey, USA
    #5
    Ok, what you may be running into is this...

    Many drive manufactures format their disks with their own format mapping schemes (mostly for PCs). The Mac can read and write to these disks (why it shows up on the desktop) but cannot boot from them.

    You need to reformat the disk using Apples mapping. Since you are running on a PPC, just run Disk Utility, select the actual disk itself (not the volume on it). Then select the Partition tab. Then from the drop down select 1 Partition (change from "current"scheme). This will enable the "options" button below. Click on the options button and then select the GUID (this is for intel) or Apple Partition Map (for PPC) partition scheme. Save all of your changes and the disk will be reformatted with the correct scheme.

    Then do the clone again.
     
  6. maclookout macrumors newbie

    Joined:
    Apr 4, 2008
    #6
    Ok, I'm a little confused here. I have an intel with GUID partition. I recently created an external FW backup drive with SD but did the default Apple Partition Map as I had not seen anything on this issue previously. All of the above info, I've confirmed in the DU since discovering this issue. However, the external drive shows up in the System Profiler> startup disk function, and I also seem to have just booted off of it. If I open either the main Mac HD or the SD external icon, it shows the external drive on top of the list of drives in the left column. So, I'm a bit new with Macs, but am I wrong in thinking this is working as a bootable drive? Will this change when I update to 10.5.2 -- I'm currently still at 10.5.1?

    I'd rather not redo this drive if it will work as is. But perhaps I should just for safety's sake?
     
  7. nambuccaheadsau thread starter macrumors 6502

    nambuccaheadsau

    Joined:
    Oct 19, 2007
    Location:
    Nambucca Heads Australia
    #7
    Ahh thanks Merl1n. You are a magician.

    Can't believe with all advice from SD forums, nowhere was it mentioned using Apple Disk Utility to partition and set up the drive using mapping.

    Boots beatifully from either Startup Disk or holding down the Option key.


    :eek:
     
  8. merl1n macrumors 65816

    merl1n

    Joined:
    Mar 30, 2008
    Location:
    New Jersey, USA
    #8
    It may work fine if the external drive has it's own power. But I ran into this with a portable external drive trying to draw power from the Firewire bus. It would not boot from firewire or usb until I reformatted the drive using the GUID partition scheme since I have a MBP which is intel.

    So the rule is:

    Intel = GUID
    PPC = Apple
     
  9. merl1n macrumors 65816

    merl1n

    Joined:
    Mar 30, 2008
    Location:
    New Jersey, USA
    #9
    Glad I could help. :)
     

Share This Page