Retina 2014 vs. 2015- SSD speeds based on architecture or sole SSD

Discussion in 'iMac' started by trayloader, Nov 9, 2015.

  1. trayloader macrumors member

    Joined:
    Sep 13, 2007
    #1
    Hi Experts,

    I´m curious if the phantastic SSD speeds in the new 2015 models are based on architecture or the sole speed of the Samsung blade SSDs in there.

    thank You
     
  2. keysofanxiety macrumors 604

    keysofanxiety

    Joined:
    Nov 23, 2011
    #2
    It's almost all down to the SSD & obviously PCI-e interface for no bottleneck.
     
  3. trayloader thread starter macrumors member

    Joined:
    Sep 13, 2007
    #3
    I´m a professional photographer and we fight with 200MB files form 80MB digital backs.So every second counts when it comes to faster opening.So if I would get access to an original SSD from the 2015 models those speeds are achievable?
     
  4. loekf macrumors 6502

    loekf

    Joined:
    Mar 23, 2015
    Location:
    Nijmegen, The Netherlands
    #4
    2014 retina iMacs don't use NVMe & 4 lanes PICe for SSDs.

    Late 2014 iMac: 2 lane PCIe + AHCI to mimic SATA-like access over PCIe
    Late 2015 iMac: 4 lane PCIe + NVMe (new protocol, less overhead)

    I would say that the biggest gain comes from doubling the PCIe bandwdith and NVMe. Of course, the SSD module
    by itself will also change, because you can access more data in parallel. Not sure how they work, but can imagine during a sequential read/write, you can access 4 locations in parallel vs. 2 last year.
     
  5. makrom macrumors regular

    Joined:
    Nov 4, 2015
    #5
    Not sure what speeds you mean. HDD has around 200 MB/s read speed plus an average access time of 10 ms, so reading a 200 MB file takes about a second if the file isn't fragmented.
    With an external 4 platter Raid 5, it should be possible to reduce it to .33s (plus the advantage of fail safety), also you can get it in sizes that could hold big archives.
    If that's not fast enough, on the internal SSD, it should be possible to read 200 MB in .07s, but you pay a high price and you won't have on the fly redundancy.
     
  6. trayloader thread starter macrumors member

    Joined:
    Sep 13, 2007
    #6
    Sorry if I wasn´t clear.
    A shooting is around 100-300 shots of 200MB files each.And that´s raw.So displaying (Lightroom,Bridge or capture one) and rendering out the stuff takes even with fast machines it´s toll.
    So my guess with 2015 vs. 2014 I would gain maybe 30-40% display and 20-30% in developing speed.
    Would this assumption be correct?
     
  7. makrom macrumors regular

    Joined:
    Nov 4, 2015
    #7
    I haven't tested this so take it with a grain of salt, but I don't see such an increase as being realistic since it doesn't depend on IO speed enough. Most of the steps you describe are bottlenecked by the CPU for the most part. You should definitely see a big advantage when batch processing images as long as you aren' doing anything too CPU heavy.
     

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