2012 Mac Mini & Fusion. Could Not Use 750GB 7200RPM.

Discussion in 'Mac mini' started by westrock2000, Jan 24, 2016.

  1. westrock2000, Jan 24, 2016
    Last edited: Jan 25, 2016

    westrock2000 macrumors 6502a

    Oct 18, 2013
    My Fusion set up crashed and it took me two days to get it back up and running before I remembered something I ran into a couple years ago.

    [For Reference Top slot means top when Mini is upside down. Bottom slot means the buried slot]

    I absolutely could not get a working Fusion setup with a 750GB 7200RPM drive installed in the Mini.

    I tried a Seagate MomentusXT 750GB "hybrid" (ST750LX003) and a Western Digital Black 750GB

    [FYI: The 750GB drives will absolutely install by themselves just fine, its only in a Fusion environment do they cause problems.]

    With the HDD in the bottom tray and SSD in top, the Fusion volume would create but OS X could not write to the volume. So it would usually fail at trying to create Recovery Partition. But even if you could trick the system to not make a Recovery Partition, it would just crash at the next thing. Time Machine also would not work.

    With the SSD in the bottom tray and HDD in the top tray, the SSD became unresponsive. When trying to do any kind of "erase" or "partition" it would fail for not being able to unmount the drive and/or volume. This was when trying to make the coreStorage volume....before making the "Macintosh HD" volume. diskutil cs create FUSION disk0 disk1 would fail for not being able to unmount disk0. So in this combination I could not even make a Fusion volume.

    Putting either a 500GB or 1TB (both 5400RPM for me) in the bottom slot and any SSD in the upper slot creates a Fusion drive with recovery partition with zero problems.

    So I don't know if it's the 7200 RPM that's the culprit or the 750GB aspect. But I would suspect the 750GB as that was a capacity not offered with Apple computers that had Fusion available.

    Mavericks CAN have problems making a Recovery Partition on an homemade Fusion setup. But Yosemite and El Capitan are fine with it. Once you blow out your Recovery Partition you will have to use Internet Recovery, which for me meant it tried to do Mavericks (in Jan 2016). So what I ended up doing was installing Mavericks to a USB 3.0 flash drive (just select the USB drive as the install destination), booted the Mini off that and then download El Capitan and made a bootable flash drive that way. Then installed El Capitan to the Fusion drive. Good to keep that USB stick around too :)

    OS X Fusion trouble 750GB, Fusion SSD slot. Using MomentusXT 750GB.
  2. gsmornot macrumors 68030


    Sep 29, 2014
    I assume since you're using it and went through the trouble to fix it, you prefer DIY Fusion setup over two stand alone drives. A new to me MAC is on the way and I have been debating which way I'm going. One thing I do know at the moment is, I don't know how to do what you did to get it working with creating boot drives. I will learn but at the moment, it's foreign to me.
  3. Celerondon macrumors 6502a


    Oct 17, 2013
    Southern Cal
    Do your homework on Fusion Drive creation and OS X installation and you will be fine gsmornot. I do want to caution you about one thing. The labels that westrock2000 uses for the hard drives are inverted and contrary to conventional practice. The upper or top drive is the one that is on top when the Mac mini is upright. The lower or bottom drive is the one that is close to the bottom cover and memory.

    I mention this only to keep you from being confused when you read instructions or descriptions that contain references to drive location. I don't suppose it matters how any given individual refers to the drive locations until they try to order parts or read instructions that use another naming convention. :rolleyes:

    This Apple Support Communities thread shows how confusion results when folks cross up the drive locations and try to follow instructions, order parts, or discuss Mac mini drive locations. The picture at the bottom of the page shows the correct labeling scheme.
  4. westrock2000 thread starter macrumors 6502a

    Oct 18, 2013
    If you put an SSD and a HDD in a Mini, it will try very hard to make it a Fusion drive. And it all honesty, it's such a stellar set up that I would recommend it. You can however split them up, but you might have to be careful about which slot you put the SSD in, as I pointed out.

    Assuming you don't have the funky issues I did with compatibility, the process is very simple.

    Also, note that if you are buying a new model, that the drive bays are different from the 2012 design.
  5. gsmornot macrumors 68030


    Sep 29, 2014
    I'm looking into it now. I have the Mini "setup" to the point its running on the new SSD. The previous, original, HDD is in as a second drive at the moment.

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