Connecting USBc SSD to USB3.0 on Macbook Pro speed issue

Discussion in 'MacBook Pro' started by supersoulfighta, Mar 17, 2018.

  1. supersoulfighta macrumors newbie

    supersoulfighta

    Joined:
    Mar 17, 2018
    Location:
    Scotland
    #1
    Hi,

    I am having an issue when connecting an external WD Passport 256Gb SSD drive to my MacBook Pro retina 2015.

    The SSD drive is rated at 500MB/s via a USBc connector. I am plugging this into my MacBook Pro USB3.0 input with is rated at around 500MB/s too.

    The problem is I am only getting 200MB/s transfer rates according to the Black Magic disk speed tool. I am trying to edit video and would like a speed closer to the stated speeds.

    The drive comes with an adaptor for the cable to go from USBc to the input on the MacBook USB3.0 standard slot.

    Please can you advise what I might be doing wrong.

    Thank you in advance,

    Callum.
     
  2. LogiLink macrumors member

    LogiLink

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    Dec 30, 2016
    Location:
    Poland
  3. chabig macrumors 603

    Joined:
    Sep 6, 2002
    #3
    No transfer protocol ever reaches its theoretical max speed. The USB port on your Mac is advertised at 5 Gbps. You’re getting half that, which is right for real world use.
     
  4. supersoulfighta thread starter macrumors newbie

    supersoulfighta

    Joined:
    Mar 17, 2018
    Location:
    Scotland
    #4
    Thanks, I really didn't realise there would be that much of a drop. Saves me buying other drives and cables. 200MB/s must be the fastest I can achieve.

    I wonder if there is a faster solution if I use my Thunderbolt 2 connection? What are "real world" achievable speeds using this bus?

    Thanks again,

    Callum
     
  5. chabig macrumors 603

    Joined:
    Sep 6, 2002
    #5
  6. Fishrrman macrumors P6

    Fishrrman

    Joined:
    Feb 20, 2009
    #6
    Something isn't right with the WD SSD.

    Moments ago, I tested an external USB3 SSD (a "bare" SSD sitting in a USB3/SATA dock) and got:
    Read: 422mbps
    Write: 333mbps

    The "practical maximum" from an SSD connected via USB3 will be writes around 430mbps.
     
  7. supersoulfighta thread starter macrumors newbie

    supersoulfighta

    Joined:
    Mar 17, 2018
    Location:
    Scotland
    #7
    Thank you very much, this is very helpful. I will look for a small (256GB), fast Thunderbolt 2 drive to use as my working drive. I should have done this from the start.

    Cheers,

    Callum.
     
  8. chabig macrumors 603

    Joined:
    Sep 6, 2002
    #8
    Thanks for posting the speed of the other SSD. Obviously the USB port is capable of getting closer to theoretical than I thought. So the WD SSD is the bottleneck.
     
  9. supersoulfighta thread starter macrumors newbie

    supersoulfighta

    Joined:
    Mar 17, 2018
    Location:
    Scotland
    #9
    Using my set up above, I'm only getting around 200. I think I will look for a Thunderbolt drive.

    Thanks,


    Callum.
    --- Post Merged, Mar 17, 2018 ---
    Agreed
    --- Post Merged, Mar 17, 2018 ---
    I'm going to try and send it back
     
  10. supersoulfighta thread starter macrumors newbie

    supersoulfighta

    Joined:
    Mar 17, 2018
    Location:
    Scotland
    #10
    What are your thoughts on the Transcend 256 GB StoreJet 500 Thunderbolt USB 3.0 Solid State Drive for Mac?

    Thanks,

    Callum
     
  11. treekram, Mar 17, 2018
    Last edited: Mar 17, 2018

    treekram macrumors 68000

    Joined:
    Nov 9, 2015
    Location:
    Honolulu HI
    #11
    If you get an external SSD that only has a TB2 connection (no USB 3.0), if you get a 2016+ MBP in the future, you're going to need to buy a TB3-to-TB2 adapter (Apple sells one for $49, and I don't think there's any alternative that's cheaper). TB3 docks don't seem to have TB2 ports on them (I just checked 3 of the more expensive ones to see if this has changed and it hasn't).

    On my 2014 Mini, I have a Crucial M500 480GB SSD. I also have a Monster Digital 240GB external TB2 SSD which supposedly has a M500 SSD in it - the SSD was modified so that it doesn't identify as a Crucial M500. My Blackmagic results were:
    M500 Internal (SATA3): 412MB write, 483MB read
    M500 USB3 external: 382MB write, 421MB read
    Monster Digital TB: 239MB write, 495MB read

    It needs to be noted that the performance of the same model of SSD can change at different capacities (larger capacity drive will perform better). Obviously, different SSD's will give different results and the M500 is an older (now discontinued) SSD.

    People's results will vary and you can see that in the Transcend reviews. But I don't think that it's necessarily worth the premium you pay for a TB drive vs. a USB drive. I like the TB drive because I use it for real-time video recording where the video data comes in on the USB port so I like to have them on separate ports in the system (although it should be said that there's likely enough bandwidth to handle both via USB). I also like it because I can enable TRIM via the TB port (not available via the USB port) and because one hour of video is usually about 7.5GB and the disk space in my case is written to and then erased usually within a couple of days, I think having TRIM is helpful.

    One alternative to get a TB drive is to get a refurbished LaCie Rugged external TB/USB3 drive with a HDD and then replace the HDD with a SSD (you void the warranty, if any). I just did that not too long ago and it was $80 (for the older model, again - refurbished) for a 1TB HDD. I can use the HDD so it really wasn't that much more than the HDD itself. I don't plan to put in a SSD immediately - it's more of a contingency should the Monster SSD fail as you can't replace the SSD in it.

    EDIT: The TB SSD's that use SATA SSD's are likely to be TB1, not TB2.
     
  12. supersoulfighta thread starter macrumors newbie

    supersoulfighta

    Joined:
    Mar 17, 2018
    Location:
    Scotland
    #12
    Thanks for the info. I have already ordered the TB transcend. It should do in the meantime.

    Thanks again,

    Callum
     

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