Homemade Fusion drive in external TB enclosure?

Discussion in 'iMac' started by bbbrisco, Nov 13, 2014.

  1. bbbrisco macrumors newbie

    Nov 13, 2014
    I just ordered a Retina iMac and after much anguish decided to go for the base 256G SSD (was considering a Fusion drive or 512G SSD as options).

    Part of my reasoning is that I'd prefer to avoid a spinning disk inside my case (suspect it is part most likely to fail, and would prefer to minimize risk of having to open up case or send it in to be serviced).

    My Windows 7 box is currently running on a 256GB SSD, and while it's a little tight I'm getting by (have a NAS for backups and media storage).

    I'm hoping that in a year or two, I can add fast external storage for less than the $330 to upgrade to a 512GB SSD. An option that looks appealing to me is making my own homebrew Fusion drive by sticking a 256G SSD and (say) a 2TB HD in an external 2-drive TB enclosure (such as http://eshop.macsales.com/item/OWC/METB7DK0GB/).

    As a sanity check is there anything I'm overlooking that would make this painful or infeasible?

    No problems enabling TRIM on an SSD in this fashion?

    Quiet is somewhat of a priority for me - would the spinning HD be put to sleep/parked most of the time (assuming most data is being served from the SSD part of the Fusion drive)?

    Any thoughts on type of HD to buy for this application (ie WD Green? Black? Blue?).

    Currently, this would be a bit pricier, at something like $250 (enclosure) + $120 (SSD) + $95 (2TB WD Green?), but I suspect those prices will fall a bit before I'd actually need it, and it would result in a 2TB Fusion drive with a beefier 256G SSD (plus the 256GB original iMac drive) instead of just a 512GB internal for $330 more.

    Any advice on issues above, or thoughts from those who have rolled their own Fusion drives, would be appreciated.
  2. rbart macrumors regular

    Nov 3, 2013
    I have an home made fusion drive on my iMac 27" 2012.
    It's made with 1Tb internale HDD (7200trs) and a Samsun 840EVO 256Gb SSD in an external TB LaCie Rugged enclosure.
    It works perfectly well, I can activate TRIM with Trim enabler on my external SSD.
    I have 400Mb/s read/write perf with blackmagic speed test.
    It's not a "recommended" setup to have an external drive part of fusion drive, but it works flawlessly in my case.
  3. mogens macrumors member

    Jan 24, 2010
    Interesting. Is the external SSD in a self powered (from the mac) dock or does it use a power supply. Do you think this setup will work with a SSD in a USB 3 inclosure?

  4. hfg macrumors 68040


    Dec 1, 2006
    Cedar Rapids, IA. USA
    Yes, you can create an external Fusion drive in a multi-bay Thunderbolt enclosure. :)

    I like to use refurb LaCie "Little Big Disk Thunderbolt" enclosures for this and replace one of the hard disks (they are normally a software RAID-0 in the dual drive enclosure) with a 256 or 512 GB SSD. I put the hard disk on the "heatsink plate" in the enclosure, and install the SSD next to it so that I can disconnect the somewhat noisy fan for quiet operation.

    I have also created Fusion drives in a Pegasus J4 enclosure, which is a 4-bay 2.5" box the size of a Mac Mini.

    The OWC enclosure you linked would work fine for larger disk drives than are available in 2.5", you will need a mounting plate for the 2.5" SSD which OWC also sells.

    You may find that keeping the hard disk portion of the Fusion spinning will provide a better experience, depending on how you use it. Try it both ways and decide what is best for you (minimum beachballs while the disk spins up).
  5. rbart macrumors regular

    Nov 3, 2013
    In my case, it's self powered through Thunderbolt port.
    It should work with a USB3 enclosure, but you won't be able to activate Trim support.
  6. mawyatt1 macrumors member

    Jul 12, 2014
    Clearwater, Fl
    This sounds interesting. Is it possible to expand the write portion of the Fusion drive to something bigger than the 4GB?

  7. rbart macrumors regular

    Nov 3, 2013

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