iMac 3TB fusion drive layout

Discussion in 'iMac' started by MrGimper, Oct 28, 2013.

  1. MrGimper macrumors 603

    MrGimper

    Joined:
    Sep 22, 2012
    Location:
    Andover, UK
    #1
    My brother just bought a pre-owned iMac with 3TB fusion drive. It was running ML.

    His drive seems to be split into 2 partitions; Macintosh HD and Macintosh HD 2

    Macintosh HD is a Logical Volume on a Logical Volume Group consisting of the SSD and a 1.5TB partition of the HDD

    Macintosh HD 2 is a Logical Volume on a Logical Volume Group consisting of just the remaining 1.5TB partition of the HDD.

    Is this layout normal?

    Cheers
    G
     
  2. jafingi macrumors 65816

    jafingi

    Joined:
    Apr 3, 2009
    Location:
    Denmark
    #2
    No, it should just be one big partition. OSX will automatically find out which things to store on the SSD and which to store on the HDD.

    I would reformat it. Start up in recovery mode, and go to Disk utility and format the hard drive to one partition and reinstall OSX.
     
  3. hfg macrumors 68040

    hfg

    Joined:
    Dec 1, 2006
    Location:
    Cedar Rapids, IA. USA
    #3
    Although not delivered from Apple configured that way, it is a popular user option for Fusion drives when you want drive space not managed by Fusion for large "static" files such as movies, video, and music files. Some users might also install Windows (BootCamp) on the free partition outside of Fusion management.

    If you wish to return it to a single large Fusion drive without reformatting and reloading everything, the "BootCamp Assistant" under your Applications/Utility folder should be able to "undo" the partitioning.
     
  4. MrGimper thread starter macrumors 603

    MrGimper

    Joined:
    Sep 22, 2012
    Location:
    Andover, UK
    #4
    Thanks for the replies. I wasn't sure if ML had a limitation on Logical Volume size, hence the split disk.

    I had already explained to my Bro that this setup may be beneficial as storing movies/downloads etc on the non-fusion partition would ensure that accessing these files would not influence the fusion drives tiering system and would keep Apps etc on the SSD.
     
  5. gnasher729 macrumors P6

    gnasher729

    Joined:
    Nov 25, 2005
    #5
    Which is daft - either these files are not used much, then they stay away from the SSD drive, or they are used a lot, in which case they move to the SSD _as they should_. And if an app isn't used, then you don't want it on the SSD.
     
  6. hfg macrumors 68040

    hfg

    Joined:
    Dec 1, 2006
    Location:
    Cedar Rapids, IA. USA
    #6
    Large files which won't benefit from SSD speeds and aren't being modified once saved (movies, music, etc.) can be isolated to a separate drive or partition which will keep them from being moved to the SSD by the Fusion algorithms, even if they are accessed every day. Much better for your SSD and overall system performance.
     

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