How bad is the 2TB Fusion?

Discussion in 'iMac' started by Cashmonee, Dec 6, 2018.

  1. Cashmonee macrumors 6502a


    May 27, 2006
    So, Best Buy has the 3.8 i5/8GB/2TB/580 on sale for $1999. This is the cheapest I have seen this particular iMac. My question is how bad is the 2TB Fusion drive? Am I going to regret getting a Fusion over an SSD? Is it possible to replace the Fusion if necessary, and if so, how difficult?
  2. Shadow Jolteon macrumors regular

    Shadow Jolteon

    Feb 1, 2018
    Mesa, Arizona
    It really depends on what you're doing. The iMac my husband and I use has the 2TB Fusion Drive and it works great for what we use it for - games from our Nintendo Switch, editing video, image editing, basic day-to-day use, etc. We configured it with the 2TB Fusion Drive due do it having a bit higher capacity SSD along with 2TB of storage space.

    The Fusion Drive is just two separate physical drives - an SSD and 3.5-inch SATA hard disk drive - configured to function similar a hybrid SSD/HDD in the software, something you can reconfigure yourself if you want/need to. Once AppleCare runs out on our computer, I plan to switch out the HDD for an SSD.

    You can find great guides on switching out the drives for iMacs on iFixIt's website. Just search for the model you're considering to find the page with guides for it. Also, a couple things about upgrading the included SSDs on iMacs: it's a pretty long process, since you'll need to remove the logic board, and certain models do not include the SSD slot unless the computer was configured with an SSD or Fusion Drive originally.
  3. vertical smile macrumors 68030

    vertical smile

    Sep 23, 2014
    There is nothing wrong with the 2 TB Fusion Drives, the 1TB Fusion Drives made after the 2014 models have a really tiny SSD, 24GB for the 2015, and 32GB for the 2017 I think.

    Compare that to the 128GB SSD in the 2TB, 3TB and original 1TB Fusion Drive.

    Ideally, the SSD would be best for many reasons, but if I needed a Mac and found a good deal on one but it had a Fusion Drive, it wouldn’t stop me from buying it.

    If it ends up being an issue, you have options, an external drive or replacing the internal HDD would do.
  4. nambuccaheadsau macrumors 65816


    Oct 19, 2007
    Nambucca Heads Australia
    It is not "bad", just not as good as a pure SSD.
  5. psymac, Dec 6, 2018
    Last edited: Dec 6, 2018

    psymac macrumors 6502

    Jul 17, 2002
    Mine had R/W speeds of 2100/700mbs before replacing with Samsung 970 EVO 500GB Nvme SSD, now 2950/2350, great improvement.
    --- Post Merged, Dec 6, 2018 ---
    Replacing the HD for a SSD won't improve the R/W speeds that much if at all, that is controlled by the 128GB SSD bus 1 Nvme blade.

    I did replace the FD with a Samsung EVO 500GB blade, great improvement. Thread here and DM if you have any questions, going carefully the first time took me about two hours. Several teardown and repair guides on ifixit and youtube.

    Tremendous improvement, so for me would never go back to a FD.
  6. vertical smile macrumors 68030

    vertical smile

    Sep 23, 2014
    I heard someone say something similar in another thread, but did not do a good job describing why this is.

    In my experience, this is not true at all. To be fair, my experience is with the original 1TB Fusion Drive on the Late 2012 iMac.

    Let me first say that I agree as long as all your stored data is on the SSD, once the Fusion Drive starts storing info on the HDD portion, the drive can no long have the sustained fast read speeds. If the data is used often, then it is moved to the SSD portion, if not, it is moved to the HDD portion.

    I can explain how the Fusion Drive operate using a real life example that I experience often, which is playing WoW. While playing on a daily basis, my load times were very fast, just a few seconds typically. If I would take from the game, and not log in for a few weeks, once I started playing again, the load times would slow down significantly.

    After playing a few times in a short period of time, the load times would would go back to a second or two.

    I also noticed this with rebooting the iMac, if I didn't reboot in a long time, sometimes I go months without restarting it, the shutdown and boot up times would be very slow, after rebooting it a few times in a relative short period of time, the shutdown and boot up would take a fraction of the time that it previously did.

    So, if you could explain why replacing the HD for a SSD wouldn't improve read times, maybe I could see it your way.
    --- Post Merged, Dec 6, 2018 ---
    I started thinking about your post again:
    Are you saying that if you replace the HDD with a SSD, the new SSD might not run as fast as it could due to it being limited by the 128GB SSD bus 1 Nvme blade?
  7. psymac macrumors 6502

    Jul 17, 2002
    You're correct, my experience was with a 2TB FD that wasn't really saturated much over the 128GB PCIe SSD. I thought of just replacing the HD with a SSD, but as long as the iMac was open, not much harder for me to go ahead and replace the PCIe SSD blade with subsequent near OEM performance. Cost for either option was nearly the same, just an extra 30" to remove and replace logic board.
    --- Post Merged, Dec 6, 2018 ---
  8. IngerMan, Dec 6, 2018
    Last edited: Dec 6, 2018

    IngerMan macrumors 65816


    Feb 21, 2011
    It’s 600’s mb/sec plus writes and 1200 + reads. It’s faster then a external Samsung T5 that people rave over.

    It’s 2TB of storage, it’s pretty darn smart and fast.

    Edit it was 1600's read

    Fusion SSD.png
  9. mikehalloran macrumors 6502

    Oct 14, 2018
    The Sillie Con Valley
    That is the big factor
    Yes, that doesn't make much sense and, in fact isn't true. But you might not notice a speed bump by replacing the HDD with a SSD in the SATA III buss. Reread the top of this post.
    Maybe yes, maybe no. Again, it all depends on what you're doing and how you use your Mac.

    You do word processing, email, watch YouTube and most streaming services, the Fusion drive is ok—pretty good since 2014 when Apple put slower, cooler HDDs in iMacs.

    If, however, you are performing tasks that require computing, the Fusion drive is way too slow as is the i5. DAWs, editing large graphics, Photoshop, FCPx all fall into this category.

    Again, it all depends.
  10. vertical smile macrumors 68030

    vertical smile

    Sep 23, 2014
    I am not sure if that is what @psymac was even trying to say. My initial impression was the post stated that replacing the HDD part of a Fusion Drive wouldn't speed things up at all, which I disagree with.

    But if this is what @psymac intended to say, I find this more believable, and makes much more sense:
    But, you say it is not true. Maybe it is not, I am not sure.....

    Even if it is not true, it still makes much more sense than my initial thought of @psymac's post.

    In theory, I can understand this, but in practice, I don't think it works that way.

    In my experience, every time I have replaced an Apple SATA III HDD with a SSD, there was a very significant speed boost. I am not saying this is true for all HDDs, but it is true for all the ones that that I have replaced.
  11. Mugwumper macrumors regular

    Jan 19, 2008
    Temecula, CA
    This is the exact same system I got in late September. Your price is a bit better than I was able to get. ;^) I was replacing an 8-year-old iMac, so needless to say, this is a screamer by comparison. But I believe a lot of that has to do with upgrading RAM to 24GB (2x8GB).

    So far, I've had no issues at all. I don't notice any lag time doing anything (except shortly after I wake from overnight sleep). I typically have 4 desktops running, and the usual assortment of apps running (Chrome, Mail, Office (word and Excel), iTunes/Sonos, Contacts, Calendar, 1Password). Once in a while, I'll run some audio apps (Audacity, YouTube to MP3), or Video Converter Ultimate to convert videos. A lot faster than previously.

    And as others have stated, "it all depends" on what YOU will be using this system for.
  12. vertical smile macrumors 68030

    vertical smile

    Sep 23, 2014
    Actually, if you are in the US, you might want to check out Apple's refurbished site.

    They have that model for even cheaper @ $1,949.
  13. joema2 macrumors 65816


    Sep 3, 2013
    I've had a 2012 and 2013 i7 iMac 27 with 3TB Fusion and they were OK. As a professional video editor I did extensive performance testing of the 2013 vs a 2015 with 1TB SSD. There wasn't that much difference in performance -- whether boot time, app load time, video transcoding, etc. However in most cases all my media was on external Thunderbolt or USB 3.0 RAID arrays.

    I'd never recommend a 1TB Fusion, but in many "light to moderate" use cases the 2TB or 3TB is OK.

    That said, all my later Macs are SSD only. It's just one less thing to go wrong. SSD doesn't slow down dramatically as it fills up like a rotating drive. Fusion slows down less as it fills up vs a HDD, but it still slows down some.

    Another reason to get SSD is peace of mind. I've seen many people post alleged iMac performance problems due to Fusion Drive, yet many of those are not I/O related. However if you don't have SSD you naturally think "maybe it's the rotating drive slowing me down". If you have SSD you don't worry about that -- even in a performance problem, you know you got the fastest available disk and the problem source is elsewhere.

    Another issue is if you use or might use Boot Camp; I don't think Windows will use the Fusion Drive, so you're stuck with a mere rotating drive. For Parallels or VMWare I don't know.

    However SSD can also cut the other way -- I've seen many people so fixated on SSD they will get a tiny config like 128 or 256 GB SSD, then put their data on a slow, rotating, bus-powered 5400 rpm USB drive. That is probably slower overall than a 3TB Fusion Drive.

    Today external SSD is a lot cheaper, e.g, the 2TB Samsung T5 is about $380.
  14. tomscott1988 macrumors 6502a


    Apr 14, 2009
    There is nothing wrong with the 2TB fusion for average users.

    The above is correct it intelligently switches data that is most used. That being said 128gb isnt much when you have the OS and a lot of apps. I bought my father the base model with the 2tb as the only upgrade and it runs fantastically and its performance is almost identical to the mac pro in my sig. That machine is 9 years old tho...

    The benchmark speeds are very deceiving because that is only the 128gb PCI-E ssd. The 2tb portion is a standard platter drive which will perform at a maximum of 150mb/s depending on how full it is.

    Im a photographer and my 2018 lightroom catalog file is sitting at over 50gb/s that doesn't include any images, this years work adds up to about 2tbs of raw images on separate platter drives. The catalog is mad up of my smart previews which I dont like to get rid of.

    You always want the stuff that needs the high performance on the SSD and with the OS, caching, Apps for me thats near enough 128gbs so my lightroom catalogue wouldn't fit and would need to be on the platter drive. This reduces performance considerably. As my cameras are high resolution I hate waiting for 100% view renders so the smart previews negate this but with slow drives they still take ages to read.

    These are the things you have to bare in mind, if your not a heavy user then you might be fine. As soon as you start doing some intense work the 128 just isnt enough and the machine will slow considerably. Any of apples OS's over yosemite arent designed to run on platter drives and the performance is really awful.

    Because of the swapping of data that 128gb portion works pretty hard and it will slow down as it ages which is another drawback, reducing its lifespan.

    For the price difference I would go SSD all in and get an external drive. 2TB drives are like £50 and you can get cheap drives all over the place. On black Friday amazon had 8tb seagate hdds on sale for £118 so I bought 2 for offsite backups.

    512gb is the sweetspot for the price/performance. A 1tb external SSD that have similar performance of over 1500mb/s read and writes are £550+ like the samsung X5

    The only benefit is that your desk is clean with internal but tbh it doesn't bother me having cables and you can manage them.
  15. maflynn Moderator


    Staff Member

    May 3, 2009
    I have a 2TB iMac and its good, I wouldn't quantify the experience as bad, though in 2018 I would be hard pressed to embrace a fusion drive, but I guess if you're saving good money then go for it. I had for a time used an external SSD and that was quite fast, so that's an option if you feel the Fusion drive is a bit slow.
  16. Cashmonee thread starter macrumors 6502a


    May 27, 2006
    I am tempted. At the refurb price on Apple's site, it is getting close to reasonable (still pricey), but I do not want to get a Fusion and regret the decision in a few years and be faced with a daunting upgrade or a slowing machine. Maybe better to wait for a refurbed SSD option.
  17. shoehornhands macrumors regular

    Oct 9, 2014
    That's running off of the SSD portion of the drive. The HDD portion of the drive will be far, far slower (likely in the neighborhood of 100 MB/sec reads and writes, with much higher latency and fewer IOPS). I think the idea is that the SSD portion of the drive is used for the OS / programs / frequently used stuff, and the HDD portion of the drive is used for large files and less frequently used stuff. I'm not sure how well the OS optimizes the SSD space, but if you use it all up and start loading programs / files / browsing images and stuff off the HDD, you will absolutely notice a significant difference.
  18. cynics macrumors G4

    Jan 8, 2012
    While I would recommend an SSD the Fusion Drive isn't "bad" by no means.

    The FD is a compromise though. It it addresses the negatives of a PCIe SSD, namely cost per gigabyte.

    The way the FD works is pretty cool too, its capable of maximizing data you use regularly onto the SSD and the less used data onto the HDD. The cool thing about it is it operates at block level, not a file level like we do. So portions of single files can be stored on the SSD and the other portion on the HDD. The portions of programs you use can be on the SSD and the portions (think about the features you don't use in any given program) can be on the HDD.

    It also knows what can't/has minimal benefit from SSD performance. Its not super beneficial to store certain media on an SSD since read speeds are limited by playback speed (bit rate). 256kbps doesn't exactly require the billions of kilobytes a PCIe can deliver.

    The HDD can become a bottleneck if you are trying to edit raw video files though as the bit rates can FAR exceed the capacity of a HDD relatively easily. But if you have a camera that's outputting data like that then its assumed you know and have the hardware to edit it.

    The larger the variety of task you do, the occurrence of rare task performed, and the amount of data the FD has on it (that you access) will determine your performance and experience. In the brief time I used a FD it felt just as fast as an SSD. However I had 100 gb of data on a 1tb FD back when the 1tb had 128gb SSD portion so of course it was fast, I never experienced the HDD.
    --- Post Merged, Dec 8, 2018 at 4:05 AM ---
    There is a lot to be said about RAM when it comes to overall system performance even more to be said about it when it comes to having an HDD.

    The only way my 2013 iMac remained useful was by maxing out the RAM and never turning it off. The majority of my programs I regularly used remained cached in RAM so they would open up lightning quick. Now that I have installed an SSD in it I notice the boot times and initial program loading times are WAY faster, seconds vs minutes. Out side of that though the performance seems very similar.

    Apples SSD's are very fast but anyone thats ever played with a ramdisk will know any SSD doesn't hold a candle to RAM. Looks at the small bit speeds....

  19. Fishrrman macrumors G5


    Feb 20, 2009
    It's worth paying extra for the SSD.
    It just... is.
    Even if the SSD is a smaller capacity.
    Add cheap external storage if you need it.
  20. Cashmonee thread starter macrumors 6502a


    May 27, 2006
    I think I agree that the Fusion is a poor choice. Refurb with SSD is probably the best option.
  21. Velin macrumors 65816


    Jul 23, 2008
    Hearst Castle
    Are you a pro user? Do you need excellent performance? If yes, do not get a Fusion Drive. They suck horribly compared with Apple’s very capable SSDs. Get the base SSD and then get a big external platter and a few flash USBs for backups and data (which is what you should be doing for data preservation).

    If you can spend a little more, the 1 TB SSD in the latest iMacs is fantastic, I’ve had it crunch through hundreds of gigs of data while processing algorithms, the kind of stuff that would utterly choke on a “Fusion” drive or even a 10,000 rpm spinner (used to run those 10ks in RAID 0, the IOPS was crazy fast, so was the risk).

    Full SSD all the way. Don’t skimp on the one I/O that can and will bottleneck your machine.

Share This Page