Replace Fusion with SSD in 27" Retina iMac

Discussion in 'iMac' started by icemantx, Jan 12, 2017.

  1. icemantx macrumors regular

    Joined:
    Mar 16, 2009
    #1
    I have a late 2014 27" iMac with a 3TB fusion drive and am considering viable options to speed up the system. Previously I upgraded the drives in my old 2009 iMac and it gave it new life. From seeing the ifixit directions replacing the HDD in the Retina iMac is more involved but certainly doable.

    So I am considering all SSD (likely Crucial or Samsung) since SSD prices have come down a lot in the 2+years since I bought it.

    My question is if I replace the HDD portion of the Fusion with an SSD (2TB), what happens to the Blade 128GB SSD already installed in the iMac? Can you then re-create an all SDD Fusion with the new drive? Have two SSDs internal?

    The main reason I would like to upgrade the drives are that it seems I am waiting on the Fusion drive to spin up with a spinning beach ball more than I like in Photos and iMovie in particular. I hear the HDD drive portion of the Fusion spinning up often.

    Thanks,

    Jeff
     
  2. Fishrrman, Jan 13, 2017
    Last edited: Jan 13, 2017

    Fishrrman macrumors G5

    Fishrrman

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    Feb 20, 2009
    #3
    The "blade SSD" that came from the factory is faster than any SSD you could install via the SATA interface.

    What may be slowing it down is that it's gotten "filled up" over the course of running for 2+ years.

    You could restore its speed by:
    1. backing up
    2. manually "de-fusing" the fusion drive into a separate SSD and HDD
    3. install OS, apps, accounts onto the SSD, BUT...
    4. Place the large libraries (music, photos, movies) on the HDD portion

    This will allow the SSD portion to run "at full speed" with sufficient free space, and leave the large libraries on the slower HDD. The speed of the drive won't matter much when you need to access them.
     
  3. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #4
    Yes you can just replace the HDD with an SSD and have a full SSD fusion drive it will be very quick but the blade will still be the fastest part due to the limitations of SATA 3.
     
  4. maflynn Moderator

    maflynn

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    May 3, 2009
    Location:
    Boston
    #5
    Nothing happens to it. You will have a 128GB drive by default. You can Fuse the original 128GB drive and the new SSD (that replaced the HD) and have a logical single drive. You'll not really see a huge performance increase but you will have a single drive which may be something you want.
     
  5. tubeexperience macrumors 68040

    Joined:
    Feb 17, 2016
    #6
    You'll get two internal drivers. That's about it.

    Don't forget to get one of these upgrade kits:
    https://eshop.macsales.com/shop/imacdiy
     
  6. tomwvr macrumors regular

    tomwvr

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    Jun 12, 2012
    Location:
    Frederick Maryland
    #7
    I just put a 750 SSD in my 2012 IMAC. The shop recommended to just go with the new SSD and not put the older SSD from the Fusion Drive in the machine.

    They said the new SSDs are faster then the old part they would remove from the Fusion Drive and with it being almost 5 years old the older SSD will die at some point
     
  7. varian55zx macrumors 6502a

    varian55zx

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    May 10, 2012
    Location:
    San Francisco
    #8
    This is exactly what I've been recommending all along and now you are in support of it?

    So many of you attack me when I propose this (even the poster?) when in reality it results in a speed increase. truly incredible.
     
  8. steve23094 macrumors 68020

    steve23094

    Joined:
    Apr 23, 2013
    #9
    The OP's plan to completely replace the drive with a SSD is a different scenario to what you incorrectly advocate on other threads. Don't try to hijack this one too.
     
  9. maflynn Moderator

    maflynn

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    #10
    Yes, but Fishrrman's post is not addressing that but rather pointing out he could de-fuse the drive and place his home on the SSD and large data on the slow spinning drive, varian55zx is not hijacking the thread but pointing out that he's long recommended that.
     
  10. steve23094 macrumors 68020

    steve23094

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    #11
    Heading it off at the pass.
     
  11. ApfelKuchen macrumors 68030

    Joined:
    Aug 28, 2012
    Location:
    Between the coasts
    #12
    It's a lot to spend unless you know that disk speed is the cause of the slowness. That's not a bad assumption based on your example - beachballs when opening Photos or iMovie libraries - but it's still just an assumption. When I look at Activity Monitor, Photos is way down the list on CPU, Memory, and Disk. Other apps/processes may be putting the real strain on the system; opening Photos or iMovie may just be adding stress to a pre-existing condition.

    I have a 3TB Fusion, too. If I haven't accessed my Photos library (400 GB) for a long while, I'll get a beachball on opening (about 10 seconds). However, I can quit/re-open Photos for quite a while after that without encountering the beachball again - presumably, I haven't done enough else to flush Photos from RAM and/or the Flash cache. Personally, I wouldn't consider that enough of an annoyance to spend the money on all-SSD. But your usage patterns may be different - the beachballs may come more frequently for you.

    Proponents of the "apps and data on SSD, data on HDD" approach tend to ignore the impact of data usage. While apps/OS on SSD can speed initial loading of OS and apps - after that, much of the code you're using remains RAM-resident - the SSD may sit relatively idle. Meantime, you use data all day long. if that data is manipulated (multiple read/writes), then all that manipulation runs at HDD speeds.

    Your example in particular would not be fixed AT ALL by having the Photos and iMovie libraries on HDD (presuming disk access speed is the cause of the beachballs).

    If you do replace the HDD with SSD... Re-fusing the drives may not result in a noticeable speed improvement over using the drives separately. The net effect might be to make the SATA SSD seem nearly as fast as the blade. That's nothing close to the obvious contrast between an HDD and an SSD. Also, the shuttling of blocks between blade and SSD consumes system resources and may impact SSD lifespan (although the wear on the blade would be no worse in this configuration than if it was fused with an HDD). However, managing the drives separately may mean a bit more work day-to-day (which app/file goes where).
     
  12. bingeciren macrumors 6502a

    bingeciren

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    Sep 6, 2011
    #13
    I'm not so sure if two solid state drives can be fused. Core storage identifies and differentiates a spinning hard drive from an SSD and knows how to shuffle blocks accordingly.

    I've done many DIY SSD + HDD fusion but never attempted a SSD + SSD fusion. Admittedly one is a blade SSD and the other is a SATA SSD, but both are SSDs so to speak.

    Has anybody actually fused two SSDs? I'd like to know if it is possible.
     
  13. steve23094 macrumors 68020

    steve23094

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    Apr 23, 2013
    #14
    Yes. This is a good point. I can't imagine why fusing two SSDs would be a problem, but can anybody speak from experience?
     
  14. bingeciren macrumors 6502a

    bingeciren

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    Sep 6, 2011
    #15
    I'm anticipating a problem because as I said, the core storage knows which drive is what and the shuffling algorithm is based on SSD (fast) and HDD (slow). If both drives are SSD, core storage would not be able differentiate which drive is slow and which drive is fast and it would probably throw its hands in the air and say sorry cannot do.

    I'd like to hear from someone who actually tried this scenario.
     
  15. hfg macrumors 68040

    hfg

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    Cedar Rapids, IA. USA
    #16
    I guess I don't see the point of trying to "Fusion" two already fast SSDs together. It would seem that all the data shuffling would be counterproductive and cause needless wear on the SSD. If your intent is to create a single entry larger drive, why not simply concatenate the two drives together into a single logical drive?
     
  16. maflynn Moderator

    maflynn

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    #17
    I've seen some threads that people have done it, and its basically a logical grouping so there's no reason why it won't work. Combining two storage devices as one. Whether it works efficiently is another story, but then at the speeds of the SSD, we'd not notice any inefficiencies.
     
  17. bingeciren macrumors 6502a

    bingeciren

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    Sep 6, 2011
    #18
    I wonder if it is a true fusion drive or some sort of a concatenated JBOD configuration. This whole idea sounds like a core storage Frankenstein project to me.

    Frankly, I wouldn't bother fusing the two SSD drives. I would simply put the OS and the user library folder to the faster PCIE blade SSD and place all the media and document files to the SATA SSD and be done with. Simple to run and to maintain it that way. This is also an optimal layout for dual boot scenarios, like Sierra and Yosemite sharing the same media and document folders for example, but that's beside the point.
     
  18. maflynn Moderator

    maflynn

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    #19
    Basically, RAID was what came to my mind but I think the concept is about the same.

    The only reason I would do it, was to keep a single volume, instead of dealing with two disks. With that said, dealing with multiple drives is not an inconvenience, so its really up to the person and their desired user experience.
     
  19. Samuelsan2001 macrumors 604

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    Oct 24, 2013
    #20
    Ah yes but I think it just identifies the separate volumes by the connection PCIe vs SATA and doesn't worry about what the actual disk is.
     
  20. iMav macrumors 6502

    iMav

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    Jun 20, 2008
    Location:
    Columbus, WI
    #21
    When you initially configure the Fusion drive, you identify the "fast" drive by enumerating it first in the disk utility command.

    That being said, as I am a fan of keeping things simple...I'd likely just do as others have recommended and create one logical drive via the JBOD raid option.
     
  21. bingeciren, Jan 24, 2017
    Last edited: Jan 24, 2017

    bingeciren macrumors 6502a

    bingeciren

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    Sep 6, 2011
    #22
    I'm still not sure of that. Because I can see that the core storage clearly identifies one disk as a solid state and the other disk as a spinning drive. I haven't really tried to fuse two SSD drives before, therefore I won't be able say anything what would be the outcome.

    I don't have a detailed technical knowledge about how the core storage decides which drive is faster. I just theorize that since it knows which one is a solid state and which one is a spinning drive, it assumes that the solid state drive is faster than the spinning drive. In other words, the built-in logic is based on a SSD + HDD combination. I doubt that the core storage looks at the physical location because no matter where I put the drives before, fusion worked without a problem.

    Therefore, I think if we throw two solid state drives to core storage and ask it to fuse them, it would be confused. I think either it would fuse them, but then there is no guarantee that the faster drive would be correctly identified, or it would simply refuse to fuse the two SSDs.

    If somebody already accomplished this, I'd really would like to know just to satisfy my curiosity. Otherwise, I think I'll just find an SSD in one of these days and put it in my MacMini to try it myself.
    --- Post Merged, Jan 24, 2017 ---
    This could be true. It makes sense, but I'm still not sure of the outcome. o_O
     
  22. Fishrrman macrumors G5

    Fishrrman

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    Feb 20, 2009
    #23
    If all the OP wants is "more operational speed", then my advice above to "de-fuse" the fusion drive will work fine.

    By "reverting" the internal 128gb SSD to "standalone status", he will have a boot SSD that will run FAR FASTER than ANY SATA SSD he could put inside it.

    Indeed, "fusing" a second SATA SSD to the factory installed "blade SSD" will SLOW DOWN the speed of the internal SSD, not "speed it up".

    The OP already has 3tb of "storage space" on the internal HDD.

    If all he needs is "more, faster" storage space, he could plug in an EXTERNAL USB3 SSD, have LOTS of extra/fast space, without breaking open the iMac and (potentially) breaking something inside...
     
  23. bingeciren macrumors 6502a

    bingeciren

    Joined:
    Sep 6, 2011
    #24
    I absolutely agree with this and this is what @varian55zx was saying all along. After experimenting with Fusion purely for academic reasons and curiosity, I de-fused my drives and I've been happily living with my SSD as my OS disk and HDD as my media and documents storage disk. End of story.
     
  24. rbart macrumors regular

    Joined:
    Nov 3, 2013
    Location:
    France
    #25
    You can fuse but it's useless.
    In this case macOS can't give a priority on the fastest drive as it considers tha both SSD (PCIe and SATA) are equal.
    --- Post Merged, Jan 27, 2017 ---
    No, the order of the drive in the array doesn't matter.
    It relies on drive technology.
     

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