Late 2012 iMac with Fusion Drive. Help please

Discussion in 'iMac' started by gdourado, Dec 29, 2014.

  1. gdourado macrumors 6502


    Apr 22, 2010
    How are you?
    I am thinking about buying a late 2012 iMac.
    I am looking at the 3.4 i7, 27 inch with 1tb fusion drive and the 680M 2gb.

    This iMac comes stock with Mountain Lion.
    I would of course upgrade to Yosemite, but I would like to do two things, if possible.

    The first is to do a clean Yosemite install.
    That can be done by downloading Yosemite and creating a bootable USB drive to install, right?

    But the other thing I would like to do is to break the Fusion Drive and have two separate drives. The SSD to install Yosemite to, and the HDD as a separate drive.
    Is this possible? How can it be done?
    I saw online some things about breaking fusion drive on the 2012 iMac, but it was old information and only mentioned Mountain Lion and using terminal.
    How is it done with Yosemite and clean install?

    Cheers! and thanks!
  2. rkaufmann87 macrumors 68000


    Dec 17, 2009
    Folsom, CA
    It is 100% unnecessary to do a clean install if you upgrade immediately, prior to installing any applications or data files. Doing so would be a complete waste of time and resources.

    Breaking a Fusion drive into two separate devices is very foolish too, again 100% unnecessary and it will likely void any warranty the machine has.

    Your best bet is to leave the machine alone and not attempt to out-think the Apple engineers. They have more experience and know what they are doing.
  3. powerslave65 macrumors 6502


    Mar 21, 2011
    Sherman Oaks CA
    I would avoid Yosemite and update to Mavericks until it is more mature. You can read countless issues with it all over these forums.
  4. inhalexhale1 macrumors 6502a

    Jul 17, 2011
    Ridgewood, NJ
    I've actually loved Yosemite. All of the bugs and annoyances I had with Mavericks disappeared when I updated to it.
  5. powerslave65 macrumors 6502


    Mar 21, 2011
    Sherman Oaks CA
  6. Yebubbleman macrumors 68030


    May 20, 2010
    Los Angeles, CA
    1. The following article tells you how to make a Bootable self-contained USB OS X Yosemite Install drive:

    2. The following article tells you how to split up a Fusion Drive. While the article is dated back to the days of OS X Mountain Lion 10.8.2, The commands remain the same for all versions of OS X Yosemite:

    3. Just an FYI, you only get a 128GB SSD with a Fusion Drive. Is that enough for your OS and apps? If not, you may not want to do that.

    4. If you're buying from the Refurbished Mac section of the Apple Online Store, said iMac may already come with Yosemite pre-installed. Just something to keep in mind if that does apply to you.

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