iMac 5K, speed differences in storage options?

Discussion in 'iMac' started by cerberusss, Feb 1, 2016.

  1. cerberusss macrumors 6502a

    cerberusss

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    #1
    I'm looking at the storage options in the latest 27" iMac 5K. Not counting the 1 TB Fusion Drive with the 24 GB SSD, there's basically:
    2 TB Fusion = 128 GB SSD + 2 TB harddrive
    256 GB SSD
    512 GB SSD

    If we simply ignore the intricacies of fusion drives, and just view it as a 128 GB SSD, what is the speed difference between the options? I can't really find benchmarks on that.
     
  2. sevoman macrumors member

    sevoman

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    #2
    Nope. All the same. There are a few videos comparing Fusion vs SSD, as far as boot time and application launch. To summarize, 99% of the time, the fusion Drive will equal pure SSD. The ONLY time you will get speedier performance with pure SSD is if transferring files greater than 4 gigs at one time. If you open a giant application that you have not used in a long long time, the fusion may be a little slower than pure ssd, otherwise on day to day usage, you will not see any differences between fusion and ssd. Again, transferring giant >4gig video files, yes you will see some difference. The fusion drive is the better deal, imo.
     
  3. cerberusss thread starter macrumors 6502a

    cerberusss

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    #3
    Well I actually wanted to leave FD out of the equation, I'm pretty convinced that it's a good choice, budget-wise.

    But I wondered if there are benchmarks that show speed differences between the SSD sizes.
     
  4. maflynn Moderator

    maflynn

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    #4
    You really can't ignore the spinning disk, the OS chooses what goes on the flash storage and what goes on the spinning disk. If you really want to deal with the 128GB flash storage, then I'd recommend splitting up the fusion drive into its components.

    From what I understand, the larger the SSD, the faster the performance given the design of SSDs, so larger models will be faster. My take on this, is you'll probably not really notice a difference between them in real world usage - just my $.02
     
  5. Samuelsan2001 macrumors 603

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    #5
    That question was answered above they are pretty much all the same on the new 4lane PCIe in the current macs. I think the 128gb on the 2TB fusion is a bit slower on writes speeds but the rest are all well above 1.5gb/s speeds on read and write, in short as others have said you will never tell the difference except under very specific use cases and even then you will only be talking seconds here or there.
     
  6. throAU macrumors 601

    throAU

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    #6
    assuming ALL of your data is cached in the 128 GB SSD, it will still be quite a bit slower than a 512 GB SSD.

    Why?

    The bigger SSDs have more NAND chips and can write to them in parallel. a 512 GB SSD will often be up to 2-4x the speed of a 128 GB SSD (depending on how many vs. size of NAND used on the drives in question).

    check http://www.storagereview.com for some SSD benchmarks for various size SSDs of same brands to get an idea of the general trend of size vs. speed.
     
  7. Samuelsan2001 macrumors 603

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    #7
    This is not so true of the 4 lane PCIe ssd's. Yes there are differences but for example the speeds on a 256gb rMBP are 2gb/s read and 1.2gb/sec write speeds. The 1TB IS 2gb/s read and 1.8gb/sec write speeds, in almost all use cases this will not matter one iota.

    See here for some benchmarks

    http://blog.macsales.com/30725-owc-tests-speed-of-ssd-in-2015-15-macbook-pro-with-retina-display
     
  8. cerberusss thread starter macrumors 6502a

    cerberusss

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    #8
    Why wouldn't it matter? Isn't that an almost 50% speed difference while writing?

    I'm a (Swift) software developer and regularly do a clean build in Xcode. That's basically a bunch of small files being written here and there. Wouldn't one notice a speed difference?
     
  9. Samuelsan2001 macrumors 603

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    #9

    Because how often do you have to write 100gb files to disk quickly??

    No sequential read/write speeds aren't important for you, I/O speed and bandwidth, core count and RAM etc would be far more important in your use case.

    Sequential read/write speeds are useful for moving around 4K video files etc.

    These speeds are impressive but it's all marketing most people won't notice the difference between a SATA 3 SSD and a 1TB apple PCIe one in most use cases.
     
  10. robgendreau macrumors 68030

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    #10
    There aren't very specific benchmarks cuz it's a use-case scenario; the whole point of Fusion is that there is a brain deciding what to optimize for speed. Anandtech had a long term test, and even they couldn't be super definitive about what's the fastest. In a particular case you could see the diff, as with huge files. But for purposes of buying? meh. I'd think that cost and issues like whether you want two drives that could fail as opposed to one would be more important factors.
     
  11. cerberusss thread starter macrumors 6502a

    cerberusss

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    #11
    I know that but your comment made me look at these benchmarks again. And indeed, when you look at small random writes (4 and 8 KB files), then the performance difference is only 10%. Still not bad, though.
     
  12. johnnyturbouk macrumors 68000

    johnnyturbouk

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    #12
    Not true,

    I have the late 2015 4GHZ rImac with 512gb ssd and blown away with the speed of the PCI-ssd. I consistently get 1500-1600 mb/s write and up to 1900 mb/s read.

    upload_2016-2-2_23-24-30.png

    If one has more than 128gb on their home folder with apps and data, then the bigger SSD will certainly outperform the fusion drive, whether this manifests in noticeable differences in the real world c.f. synthetic benchmarking remains debatable.

    I have my home folder and app on my mac, my iTunes and photos on an external 512 ssd via TB enclosure, and the entire drive linked to my qnap server via ethernet. Thus for me, 512gb is ample, a shame i sacrificed 32gbs of it for windows out of necessity for my work needs.
     
  13. maflynn Moderator

    maflynn

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    #13
    Unless you split up the Fusion drive, you have no say on where the data is placed, some blocks of data will be on the flash storage, some will not.

    The beauty of the Fusion drive is that you get near SSD speeds for most normal usage needs, at a much reduced cost. My storage needs are such that even the 512GB ssd was insufficient and I'd rather not deal with external drives - I did that for years. Its nice to have my picture library centrally located on one drive.
     
  14. mmomega macrumors demi-god

    mmomega

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    #14
    I just did a test on my 2015 i7 512GB.
    The test varied a little but was roughly 1500MB/s writes and 1900MB/s reads.



    Screen Shot 2016-02-04 at 11.23.46 PM.png
     
  15. throAU macrumors 601

    throAU

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    #15
    Anything up near a gig a second is, for most purposes plenty, so yeah unless you're dealign with very much niche uses then any of the SSDs will be enough. But the bigger ones ARE faster.

    If you use FileVault it is kinda academic anyway as (at the moment with reasonably current CPUs) you'll be limited by the throughput of the encryption, at least on the 13" macbook pro for example. I think my read/write speeds dropped to 700-800 megabytes a second or so with file vault from memory. Which is still plenty fast enough for most uses.
     

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