Wait.. SSD through external is slow??

Discussion in 'SSDs & Data Storage' started by maxiedaniels, Mar 5, 2014.

  1. maxiedaniels

    maxiedaniels Gawd

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    http://www.macworld.com/article/2039427/how-fast-is-usb-3-0-really-.html

    Just got my new Mac Pro in, and I'm going to be setting up either a Thunderbolt bay with multiple SSD's, or just individual external enclosures with SSD's.

    While I was looking into the differences in speed between Thunderbolt and USB3, I noticed this article. They only got ~350mb/s read/write with Thunderbolt, and ~160mb/s read/write with USB3.0.... the SSD they used normally has a read/write of +500mb/s.

    Is this normal?? I don't understand how it's so much slower than it should be...
     
  2. westrock2000

    westrock2000 [H]ardForum Junkie

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    Overhead issues, chipset (on the enclosure) implementation, driver implementation. Lots of little reasons.
     
  3. rastaban

    rastaban Gawd

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    I recall reading in an Anandtech review that Thunderbolt is highly RAM dependent. It's possible that the 8GB of RAM in the macworld review wasn't enough to take full advantage of TB transfer speeds.

    edit: hmm I can't find the source or anything close to it anymore so perhaps I'm making stuff up...
     
    Last edited: Mar 6, 2014
  4. maxiedaniels

    maxiedaniels Gawd

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    Yeah but the USB3.0 transfer speeds are slow too..
     
  5. timta2

    timta2 [H]ard|Gawd

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    Please make sure you use MB and Mb correctly. There is an x8 difference between the two.
    http://en.wikipedia.org/wiki/Megabyte
    http://en.wikipedia.org/wiki/Megabit

    Also please keep in mind that the SSD they used offers speeds "Up to 559MB/s Read, 527MB/s Write". It's a very common marketing technique that can be misleading to people that don't understand what that means.
     
  6. maxiedaniels

    maxiedaniels Gawd

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    Apologies - I know the difference... but that doesn't change the fact that the numbers seem very slow.

    I've looked up the tested numbers of that SSD (not just the manufacturer's claim) and the drive tends to hit ~500MB/s... USB3.0's bandwidth is supposed to be around 625MB/s, which, even if you halved that, isn't close to the $160MB/s they reported.

    Thunderbolt is closer, but still..
     
  7. Ryokurin

    Ryokurin [H]ardForum Junkie

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    USB 3 has it's own overhead and protocol issues. Not every system supports UASP mode for example, and even then some systems handle that mode in different ways.
     
  8. Old Hippie

    Old Hippie [H]ardness Supreme

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    What drive are you using?
     
  9. socold

    socold n00b

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    maybe bad machine?
     
  10. Tsumi

    Tsumi [H]ardForum Junkie

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    Not all USB 3.0 controllers are built equally. Some will perform better (faster) than others. Thunderbolt is a direct PCI-E connection, so speed will depend on the Thunderbolt-SATA controller. Again, not all SATA controllers are built equally.
     
  11. maxiedaniels

    maxiedaniels Gawd

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    Okay, got my Startech USB3.0 -> SATA dock in today. Tried my SSD (which in tests read/writes at ~400MB/s) using Blackmagic. My read is testing at 120MB/s, and my write is testing at 150MB/s)..

    This seems slow. I know to Startech dock is SATAII, but that should only limit things to 384MB/s...

    Thoughts?
     
  12. maxiedaniels

    maxiedaniels Gawd

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    ***just noticed the Stardock adapter doesn't have UASP listed... Is this needed for proper speed?