What happens when you replace the 1TB HDD in the Fusion drive with a SSD?

Discussion in 'Mac mini' started by VapoChimmy, Dec 17, 2014.

  1. VapoChimmy macrumors newbie

    Nov 12, 2014
    Hello all.

    So I am wondering, if I get the $999 2014 mini; and I replace the 1TB HGST 5,400 RPM hard drive with a SSD, will it work right?

    It appears the Fusion drive in the $999 2014 mini uses a samsung PCIe SSD and uses drive caching. I don't know if it's intel's smart response tech (http://www.pugetsystems.com/labs/articles/How-it-Works-Intel-SSD-Caching-148/ ) or if apple has a different system.

    I know the PCIe SSD is faster than a SATA based SSD, but would the replacement of the 5,200 RPM drive with a SSD that is much much faster cause problems with how the fusion drive works? Basically a slightly faster SSD trying to cache another SSD.

    I'm thinking about getting the $999 drive because it's faster, but if it turns out that the Fusion drive will prevent me from running all SSD then the $700 mini might be a better choice.

    This is what the 2014 mini Fusion drive looks like inside

    This is a guide to replace the HDD on the 2014 non-fusion

    Mac Mini 2014 teardown

    iFixit comments in Step 9
  2. thunng8 macrumors 6502a

    Feb 8, 2006
    You can uncouple a fusion drive using disk utility. Of course you will lose you data and need to reinstall the os.

    Fusion is apple propriety and does not use any Intel tech

    More info here

  3. VapoChimmy thread starter macrumors newbie

    Nov 12, 2014

    Interesting. So if I replaced the HGST 1TB 5,400 RPM drive with a 1TB SSD. And then uncoupled the drives, I would end up w/ a 1TB SSD and a 128GB PCIe SSD; showing 2 separate drives on the OS?

    If I ran bootcamp would Windows 7 or 8 be able to see both drives as well?
  4. scoobdriver macrumors member

    Aug 1, 2011
    I'd uncouple the drives first, however , just replacing one drive in the fusion volume will break it anyway and disk util should offer a repair
  5. s0nicpr0s macrumors regular


    Sep 1, 2010
    I know when they're still coupled together as a fusion drive, that windows can't see the SSD. But I'd imagine that if you separated them first, a bootcamp image would see both drives just fine. The only dual-drive mac I've used is a mini server I've got set in raid for the redundancy. Hence, only a single drive is seen and used.
  6. VapoChimmy thread starter macrumors newbie

    Nov 12, 2014
    Do 2014 Mac Minis come with an OSX disc?

    So it looks like to decouple the drives I need to format them, destroying the recovery partition. If I do that, how do I reinstall OSX?


    I have an old copy of Mountain Lion on disc, but my understanding was that the newer Macs can't run the old versions of OSX.
  7. scoobdriver macrumors member

    Aug 1, 2011
    Internet recovery will still work. Or you can use a pre made bootable usb stick if you have one.
  8. VapoChimmy thread starter macrumors newbie

    Nov 12, 2014
    Ok, thanks. So I just have to make sure I do that before I do the decouple then.


    One other thing I'm noticing is that the articles I've read on decoupling a Fusion drive seem to be talking about decoupling two SATA drives.

    From my understading this 2014 mini uses a PCIe 128GB Samsung SSD and a SATA 1TB HGST 5,400RPM mechanical.

    Would the fact that it's a PCIe drive and not a SATA drive cause problems with decoupling? I see the 2013 iMac also has a PCIe SSD, does the same decoupling method work on that the same (as decoupling 2 SATA drives in fusion)?
  9. scoobdriver macrumors member

    Aug 1, 2011
    Make a usb yes. But Internet recovery will still work after decoupling , it doesn't need a working startup disk. I'd not worry to much , chill out. As long as you can boot to disk utility / terminal you'll beable to sort it out. You can rectify it even if you just take the spinner out without doing anything first.
  10. marzer macrumors 65816


    Nov 14, 2009
    I agree with scooby, don't over think it. Fusion is just a logical layer of the OS X file system. It only sees mass storage devices and doesn't matter what the underlying physical connection is. Just for SAG I made a Fusion drive using a USB stick and SD card.

    For simplicity sake, delete the Fusion volume and individually format the two internal drives. Pull the spinner out and install your 1TB SSD, format it as a standalone drive. Install OS X on the drive of your choice and restore your data.

    If you have an interest in Bootcamp, the 128GB SSD would make a good Windows standalone drive.

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