How do you create a bootable Lion/Mountain Lion System (not installer) on external HD

Discussion in 'macOS' started by jjw1980, Aug 15, 2012.

  1. jjw1980 macrumors newbie

    Aug 13, 2012
    So with leopard and SL retail disks I used to install a system on an external HDD (GUID, HFS+) and it would boot any Mac released before that system iteration (as long as all osx updates were installed). As long as you used the retail disks and not the grey disks from the box it would install all drivers for the existing Mac range.

    I had a 10.5.8 system on a partition and it would boot any leopard compatible mac. Same with SL and 10.6.8. Just alt boot in and you are there!

    I can install lion/ML on an external drive in the same way, however, the installer seems to check which mac is being used and only installs the relevant drivers. This means if you have created the system on a MBP it won't boot an Imac, just the exact same product family mac.

    Anyone know a trick to get round this? I like to carry my own systems around for troubleshooting hardware and software issues at work. Also if I have to use someone else's Mac I just plug in my 2.5 usb powered HD and boot into my own system, really handy for certain things.
  2. r0k macrumors 68040


    Mar 3, 2008

    That's very bad news. I only have one mini new enough to run ML. I have ML on an external disk but never tried booting any of my other (even older) Macs because they don't support ML in the first place.

    I suppose one could argue this makes the install image smaller but frankly I'd much rather have a disk that is bootable on more than one Mac. (If I owned more than one Mac capable of running ML in the first place.)


    Of course in considering your question, one thing does occur to me... You mention not being able to boot on "just any" machine... Are any of the machines you're trying to boot incompatible with ML?
  3. DewGuy1999 macrumors 68040


    Jan 25, 2009
    I might be wrong here, but I think if Lion or Mountain Lion either came installed on a Mac or was acquired as part of the Software Up-to-Date program then it's "owned" by the Mac and can only be installed on that Mac, kind of like the old grey restore discs. If Lion or Mountain Lion were purchased separately then I believed they are "owned" by the purchasers Apple ID and can be installed on any Mac they own, kind of like the old retail discs. I don't have any first hand experience with Lion or Mountain Lion, yet, so I may be wrong.
  4. jjw1980 thread starter macrumors newbie

    Aug 13, 2012

    No, I am only trying to boot to ML compatible machines, should have been clearer here.

    Dewguy: from my understanding the lion/ML liscence through the app store purchase grants you 5 personal licences for any compatible mac.
  5. Jab00 macrumors regular

    Jun 12, 2012

    Okay so I installed Mountain Lion on my computer last month and made sure to keep the install file and since then have attempted many methods of making a bootable drive/DVD. Every drive I have made says it was sucessfully done but when I try to boot it from a computer the apple symbol turns to a circle and slash or it just never boots... any idea why??
  6. jjw1980 thread starter macrumors newbie

    Aug 13, 2012

    If you are trying to boot it from a different mac than the one you used to install the system in the first place, you have hit the crux of the issue this thread is about. It doesn't have the right drivers to boot other macs.

    If you are trying to boot the system on the same mac and it doesn't boot, it could be another issue. Check the drive is setup to GUID partition table and HFS+ formatting scheme.
  7. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    I believe you are mistaken here. If you DL the full ML install from the App store, that DMG file is the same no matter what machine you DL it to. If you search earlier threads you will see users even compared the MD5 hash and they are all the same. The resulting USB key installer would work on any ML supported machine. There are many posts on here from users who made a ML USB key and used it to install ML to all their Macs.

    What you might be thinking of was an issue with new machines and Lion 10.7.4. For example, the 2012 Macbook Air came with a special version of 10.7.4 and the 10.7.4 version from the App store would not work. But at this point ML is all the same.

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