Installing ML on another partition

Discussion in 'OS X Mountain Lion (10.8)' started by pj-uk, Jul 22, 2012.

  1. pj-uk macrumors member

    Mar 25, 2011
    I'm getting ready for the release of ML and wondered if it was possible to install ML onto a second partition just in case there are some big issues with ML/software compatibility.

    I currently have around 300Gb free on my primary disk and will create a secondary partition to install ML and copy over all my important documents rather than doing an upgrade or copying everything to an external disk.

    Once I've installed (and happy with the performance!) can I just wipe my Lion partition and join the two partitions back together?

    Does this sound feasible? If SHTF at least I will have OS to fall back on to!
  2. fatefulwhisper macrumors regular

    Jul 24, 2008
    Yup, this works. In fact, I've done this multiple times and haven't run into any issues.
  3. nampramos macrumors 6502

    Dec 14, 2010
    I'd like to use this topic (if the owner doesn't mind) to try figuring out why I am getting an error when restoring a ML dmg into a USB stick.

    I formatted it to a GUID partition and when the restoring process of the dmg finalizes I get the following message:

    "Restore Failure

    Could not restore - Invalid argument"

    Any ideas?

  4. pmau macrumors 65816

    Nov 9, 2010
    If you type

    diskutil list

    after having installed ML on a second partition, you might discover the following has happend:

    Lion Recovery HD
    Mountain Lion
    Mountain Lion Recovery HD

    So, no easy merging possible.
    I would advice performing a clean install after having backed up Lion to a cheap external USB drive.
  5. fatefulwhisper macrumors regular

    Jul 24, 2008
    I have noticed this as well, but the moment you delete the ML partition (using Disk Utility in Lion), it will also automatically delete the ML Recovery partition with it. Then you can merge the free space you created to the original Lion partition (essentially recovering the free space back).

    But backing up isn't a bad idea; I highly recommend it nonetheless, and it should always be done--it's kind of a given when you're doing a lot of testing.
  6. pj-uk thread starter macrumors member

    Mar 25, 2011
    Everything is already backed up on TM, but want to start afresh! I guess the Lion and Recovery partition will also delete if I stick with ML? ;)
  7. fatefulwhisper macrumors regular

    Jul 24, 2008
    If you upgrade from Lion to ML, then your Recovery partition will also upgrade to the ML version.

Share This Page