using a Samsung 850 SSD as external - is Thunderbolt 3 faster than USB 3?

Discussion in 'iMac' started by imacken, Mar 17, 2018.

  1. imacken macrumors 65816

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    #1
    I currently have a Samsung 850 SSD plugged in via a USB 3 enclosure. If I transferred it to a USB C enclosure would the transfer rate be faster on a iMac 2017 Thunderbolt 3 port?
     
  2. gian8989 macrumors 6502

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    #2
    Yes but you probably won't notice a difference. On the other end you would be able to enable trim.
     
  3. jerwin macrumors 68020

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  4. imacken thread starter macrumors 65816

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    #4
    I'm getting about 260MB/s read and write. How does enabling Trim help?
     
  5. imacken thread starter macrumors 65816

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    #6
  6. chabig macrumors 603

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    #7
    Thunderbolt is faster than USB, but you’d have to buy a Thunderbolt 3 enclosure and they are expensive. I think you’re confused by the fact that Thunderbolt 3 uses the USB-C connector. The various generations of USB are identified by number, (USB 2, USB 3, USB 3.1) while the connectors have alphabet names (USB-A, USB-B, USB-C). The USB type C connector is very versatile and can carry signaling for all generations of USB, Thunderbolt, Ethernet, HDMI, DisplayPort, and power.

    See https://en.wikipedia.org/wiki/USB-C

    So to answer your question, simply moving the SSD to a new case with a USB-C connector won’t make it faster if it’s a USB case. Putting the SSD in a Thunderbolt case will make it faster, but at great cost.
     
  7. Weaselboy Moderator

    Weaselboy

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    #8
    A TB enclosure won't be much if any faster than a good USB3 enclosure. See this.

    That said, your speeds look slow. What USB enclosure are you using and does it support UASP?

    With that drive you should easily be able hit around 400MBs.
     
  8. imacken thread starter macrumors 65816

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    #9
    Thanks, I'm not totally confused, just a bit! I thought that if I connected a drive via the USB Type C port (TB3) on the iMac, then I should get USB 3.1 speeds using an appropriate cable. I appreciate that I wouldn't get TB3 performance, but felt it might improve on USB 3.0. Is that wrong?
     
  9. SoyCapitanSoyCapitan macrumors 601

    SoyCapitanSoyCapitan

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    #10
    No. The 850 is a SATA3 SSD. At best it consumes the bandwidth of USB 3 but not 3.1 or Thunderbolt 2/3.
     
  10. Glockworkorange macrumors 65816

    Glockworkorange

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    #11
    TB 3 will be faster but of course, not as fast as PCIE.
     
  11. chabig macrumors 603

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    #12
    USB 3 has two varieties, either 5Gbps or 10Gbps. These are now known as USB 3.1 Gen 1 and USB 3.1 Gen 2. Current Macs only support the 5Gbps USB Gen 1 speed. So you probably are getting USB speed, just not as fast as you expected.
     
  12. imacken thread starter macrumors 65816

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    #13
    No, apparently it doesn't support UASP, but I've just ordered one that does!
     
  13. Weaselboy Moderator

    Weaselboy

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    #14
    Yeah... that should help. Let us know how it goes with the new enclosure.
     
  14. dlewis23 macrumors 6502a

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    #15
    A thunderbolt 3 enclosure thats using thunderbolt 3 will be faster than a USB3 enclosure, and more responsive when used as a primary drive. Use a NVMe drive in the thunderbolt3 enclosure and it will be significantly faster.

    Something like this: https://www.amazon.com/Cable-Matter...sr=8-1-spons&keywords=thunderbolt+3+ssd&psc=1
     
  15. Weaselboy Moderator

    Weaselboy

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    #16
    I think you are misunderstanding what I said or meant. In the context of this thread and OP's SATA interface drive, USB3 is more than capable of handling the max throughput of the drive. TB3 is not really relevant to what we are discussing here.
     
  16. J.Gallardo macrumors regular

    J.Gallardo

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    #17
    I’m using an external case for a Crucial MX500, but it’s a case that supports USB 3.1 gen 2, which last iMac provides through usb-c port (that also gives Thunderbolt 3 compatibility).
    I’ve got also a SanDisk Ultra connected to USB 3.1 gen 1.
    The bottleneck here is SATA interface in SSDs... BUT USB 3.1 gen 2 is a little bit faster (430+ against 500+ Mb/s, roughly). Not a big gain... and it depends on SSD also... but a slight difference.
     
  17. BigMcGuire Contributor

    BigMcGuire

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    #18
    This is a must - UASP enclosures cost a bit more but completely worth it. In regards to UASP vs non - You won't really notice a ton of difference on day to day operations but booting up on a Samsung 850 SSD is almost 2x faster and gaming can be very noticeable as well.

    Re: Thunderbolt / USB C vs USB 3.0
    I side with Weaselboy here - stick with USB 3.0 - that with UASP - you're good to go. Everything else is too expensive.
     
  18. Fishrrman macrumors P6

    Fishrrman

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    #19
    OP wrote:
    "I'm getting about 260MB/s read and write. How does enabling Trim help?"

    IF that's all the speed you're getting, you're not using the correct enclosure.

    With a USB3 enclosure (or a USB3/SATA dock, or a USB3/SATA adapter/dongle) THAT SUPPORTS UASP (very important), you should see speeds of roughly:
    Writes: 430mbps
    Reads: 275-350mbps (depends on drive brand and size).

    That's what I've been getting by booting and running my 2012 Mini (via USB3) for over 5 years now.

    Regarding TRIM -- it's a total non-issue and will make next-to-no difference for most folks. Has NEVER been an issue for me.

    Thunderbolt3 (or even USB3.1 gen. 2) will BOTH be faster.
    But... there aren't many drives that support this yet, and the ones that do are quite expensive.

    Are you booting externally?
    Or just using the SSD for data storage?
     
  19. filmak macrumors 65816

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    #20
    I think that usually reads have better speed than writes.
     
  20. J.Gallardo macrumors regular

    J.Gallardo

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    #21
    Captura de pantalla 2018-03-19 a las 20.53.33.jpg
    Crucial MX500 1Tb SATA SSD installed in Plugable case (30€), usb 3.1 gen 2 (usb-C port) to iMac 2017.
     
  21. imacken thread starter macrumors 65816

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    #22
    OK, so I installed the Samsung 850 EVO 500gb into the new UASP compatible enclosure, and wow! What a difference.
    Blackmagic and Crystalmark read/writes have gone from 240/230 up to 440/430! Almost double. Windows boots in 20s compared to about 35s before.
    Thanks a lot for your advice here guys. I had never heard of UASP till this thread!
     

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