will the 1tb fusion drive run slow after years?

Discussion in 'iMac' started by 65301361, Oct 10, 2018.

  1. 65301361 macrumors member

    Sep 24, 2018
    is it safe to go with the 1tb fusion drive. I know the ssd is just 32g. but I can accept the speed of raw 7200hdd. but I heard some people complained that it runs even slower than the hdd after some update or something. so anyone used the 1tb 32ssd version fusion drive can share some experience here?
  2. nambuccaheadsau macrumors 68000


    Oct 19, 2007
    Nambucca Heads Australia
    The 'speed' of even a 7200rpm drive is slow as molasses. If the money runs to it, go with say a 256GB SSD and an external if storage is needed. The average person uses some 60GB of storage space just for the operating system, not including what bin some cases are large applications.

    Nothing spoils your new computing experience more than a slow hard drive.
  3. bbnck, Oct 10, 2018
    Last edited: Oct 10, 2018

    bbnck macrumors 6502a

    Mar 19, 2009
    Unfortunately, we have a lot of people on this forum spreading misinformation about Fusion Drive systems, which in turn encourages other people that ought to know better to repeat it like children, even though they've never used a Fusion Drive system for themselves (just a general observation, nambuccaheadsau, not directed at you). The truth is all Fusion Drive systems offer good performance out of the box. I have an iMac with a 1 TB Fusion Drive and I use this machine for software development. I've had it for over a year now.

    If you want maximum performance, upgrade to an SSD. However, performance of Fusion Drive systems are perfectly acceptable unless you are doing I/O heavy pro work (video production, macOS and iOS app development, etc.) I have a 13-inch 2.3 GHz MacBook Pro at work and apps take far longer to launch on that machine than they do on my iMac and I suspect this is due to the limited amount of memory on that machine compared to my iMac at home, or the processor, or both.

    I have the base 27-inch iMac configuration with 16 GB RAM.

    The advantages of an SSD:
    • They retain maximum performance until they reach end of life and malfunction.
    The disadvantages of an SSD:
    • They are far more expensive than a Fusion Drive.
    The advantages of a Fusion Drive system:
    • Good value to performance ratio: SSDs are still far too expensive for equivalent storage capacity.
    • Faster than a standard hard drive and as close as you are going to get to SSD performance without the expense of a standalone SSD system.
    The disadvantages of a Fusion Drive system:
    • They will slow down as the hard drive in the Fusion Drive system starts to reach the end of its life. However, I've used a 2013 iMac with a 7200-rpm hard drive at work and five years on, it's still as fast as I would come to expect from a hard drive. I imagine a few more years and that machine may start to show its age.
    To summarise very simply, if you want GOOD performance, get a Fusion Drive system. But if you want the BEST performance, get an SSD only system.

    So hopefully now you have all the information you need to make an informed decision for yourself.
  4. wardie macrumors regular

    Aug 18, 2008
    There is another factor to consider which is reliability. I’m not sure there is much raw difference is reliability between a SSD and HDD per se (source not my own experience but people that use an awful lot of them: http://www.enterprisestorageforum.com/storage-hardware/ssd-vs.-hdd-performance-and-reliability.html ).

    However a Fusion drive is actually a logical combination of both a physical SSD and a HDD, hence the name. Therefore you are exposed to more reliability risk (higher failure rate) due to a working drive using two components either of which could fail and take down your fusion drive and likely all its data. There are a few threads on the forum where one half of a fusion drive has failed and people need to recover and salvage the working hardware bit left.

    Just one consideration, versus the large price per GB advantage and relatively performance low performance hit in most normal user workloads.
  5. ApfelKuchen macrumors 68030

    Aug 28, 2012
    Between the coasts
    I've been running an iMac with Fusion drive since early 2014. It has not slowed down at all. It runs far better today under Mojave than it did with its original OS, Mountain Lion.

    Eventually, hard drive performance will degrade due to accumulating errors on the drive surface. However, since Fusion puts the most-used data into SSD/Flash storage, there's less wear on the HDD than would typically occur.

    So if someone says, "My Fusion is running slower," my answer would be, "Are you guessing, or did you eliminate all the other factors that can lead to system slowdown?"
  6. Fishrrman macrumors P6


    Feb 20, 2009
    I believe that the recent 1tb fusion drives (the ones with the 32gb SSD portion) WILL begin to "slow down" over time, as the SSD portion will "fill up" quickly and also because of a high amount of reads/writes to it.

    I could be wrong.
  7. ApfelKuchen macrumors 68030

    Aug 28, 2012
    Between the coasts
    Yes, you could be. ;-) You've often voiced your skepticism of Fusion, but afaik, you've yet to back up your beliefs with experience.

    The Flash cache in a Fusion drive is little different than RAM, in that it's actively managed and designed to be filled, rather than left empty. When cache-resident data/code goes unused it will eventually be replaced by data/code that has current need to be there. There will inevitably be some data/code that is almost constantly Flash-resident (core OS modules) - "wear" of that portion of the drive would be little different than the wear on an all-Flash SSD drive - lots of reads, far fewer writes. The less-frequently-accessed data/code by its very nature will see fewer reads, which eventually leads to new writes. It's not likely that any one particular section of Flash is going to be seeing high-frequency read/write thrashing.

    Comparing the wear/utilization of a Fusion drive with 128 GB Flash vs. 32 GB Flash, you might use the RAM analogy once more. Some Mac users need no more than 8 GB RAM to obtain adequate performance and others may require 32 GB or more. It depends entirely on what they do with their Macs.

    I'm willing to trust that Apple has learned enough about Fusion cache utilization over the years that they knew that the typical, economy-focused Fusion user only needs 32 GB Flash, the same way they need only 8 GB RAM (not unlike the typical driver who needs no more than a 4-cylinder, 2-liter engine). I'm fairly well convinced that my 128 GB Flash cache is grossly under-used, just as I can tell (by constant use of Activity Monitor) that my 16 GB of RAM is more than I need.

    In my particular case, nearly 500 GB of my 3 TB Fusion, late 2013 iMac (of which only 1.2 TB is occupied after nearly five years) is photo library. The predominant write activity there is in the edit metadata, which are very small files compared to the images (non-destructive editing means the master images are write-once, and the preview, thumbnails, and metadata are only re-written while editing the corresponding image). A Fusion drive seems perfect for this kind of use, as the vast majority of the data is inactive, and the data that is being actively utilized is very small (24 MB master images, 100 K previews, and even smaller metadata).
  8. wardie macrumors regular

    Aug 18, 2008
    It’s not just a cache it implements tiered storage, as well as write caching. So your data is on either not both, based on read frequency
    So I’d be pretty sure that it will mostly fill up the SSD space available, so bigger is better as higher likelihood of reading your files fast. I doubt it is sitting there mostly unused. There are various bloggers that have tried to figure out exactly how it works as Apple’s details are sketchy.
  9. nambuccaheadsau macrumors 68000


    Oct 19, 2007
    Nambucca Heads Australia
  10. Hater macrumors 6502a


    Sep 20, 2017
    Edinburgh, Scotland
    It a few commands to split the Fusion drive into two separate internal drives you can manage independently.

    Either way, "Slow as molasses" my arse.
  11. ApfelKuchen macrumors 68030

    Aug 28, 2012
    Between the coasts
    Why does the "manage independently" concept still exist? I've used Fusion, with absolutely no need for human intervention, since early 2014. I also have an all-Flash iMac. In day-to-day use, I can't tell the two apart. Both boot about as quickly, neither bogs down waiting for large resources to open. To borrow a well-worn phrase, it just works.

    Further, because Fusion moves blocks, not entire files, it can accomplish something I can't do manually - move only those parts of a file that are actually called by the CPU. That's why entry-level Fusion drives manage to get by with just 32 GB of Flash.

    Modern apps and OSes are highly modular. How can I possibly know which modules out of the the thousands of items in my 13.89 GB (macOS) Library and 10.95 GB System folders are needed at this moment? There are dependencies upon dependencies. Since I can't know this, "manually manage" means putting the whole bloody OS into expensive Flash storage, and leaving it there. 24 GB of Flash just to be sure some obscure command or plist file is Flash-resident if and when it's ever needed. And this is just as true for apps. If you View Package Contents of the typical major app (like 540 MB of Pages or 2.04 GB of Logic Pro X), you'll find hundreds or thousands of files and folders within. Which of those deserve to be Flash-resident, which sit totally unused?

    If I were to truly "manually manage" a limited amount of Flash, I would want to move active data files there, not just apps and OS. Data most certainly benefits from the speed of Flash. So, I'd have to take the time to Move from HDD to Flash, then Move back to HDD when I'm done with the file. Move, not Copy, because otherwise I have two versions of the file and the next time I'd have to sort out whether I should over-write the version in Flash with the (possibly older) version on the HDD, or vice versa. Yet if I forgot Move something back to HDD when done, I'd have to Search to know which drive held that file....

    I hate being a file clerk. It's not my job to know what bit and byte I'll need next, or where to put it when I'm done. That's what an operating system is for. I've "hired" my computing devices to do all the fetching and storing, so I can use them for something productive.
  12. greyeyezz macrumors newbie

    Mar 29, 2017
    Been using a Fusion drive for a year and eight months on a late 2015, has not slowed one bit.

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