USB 3.0 HDD going at "belowUSB2.0"

Discussion in 'Mac Accessories' started by Damian83, Mar 7, 2015.

  1. Damian83 macrumors member

    Joined:
    Jul 20, 2011
    #1
    Hi just got a seagate 5tb expansion hdd, connected it to my imac late 2013, checked if both hdd's, (the new and the other seagate 4tb backup plus) are at 5gbps speed. all ok! started copying the 4tb files from old hd to the new. for about 30min speed was ok, then it slowed at below 480mbps, tried blackmagic speed test and it goes at around 10mbyte ps. checked the speed from utility and its still 5gbps but the problem is that it consumes only 8mA current while the other hd requires 144. usb bus dont get enough current. how to fix it???

    [​IMG]
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  2. ColdCase macrumors 68030

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    NH
    #2
    Your slow data rate has nothing to do with current, thats irrelevant. You probably have a bad drive or cable. Try another cable then contact seagate customer support or the place you purchased. They will likely exchange the drive.
     
  3. Damian83 thread starter macrumors member

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    Jul 20, 2011
    #3
    rebooted, this time with only 5tb connected. seems fine. are those speeds correct?

    [​IMG]
     
  4. ColdCase macrumors 68030

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    #4
    looks in the ball park for USB3 and a rotational 5TB drive. Did you say you were using a hub?
     
  5. waw74 macrumors 68030

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    May 27, 2008
  6. Damian83 thread starter macrumors member

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    Jul 20, 2011
    #6
    no, directly connected to imac

    normal for such drive?
     
  7. ColdCase macrumors 68030

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    #7
    Yes normal for a 5TB consumer USB3 drive such as the Seagate expansion..
     
  8. westrock2000 macrumors 6502

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    Oct 18, 2013
    #8
    Yes, there is the speed of the protocol (USB3) and then the speed of the device itself (the hard drive). USB3 can support up to several hundred megabytes per second, but a spinning hard drive can only must about 100-150 normally. And that's a best case scenario, you start copying lots of small files and that number will drop considerably.
     
  9. matreya macrumors 65816

    matreya

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    Nov 14, 2009
    #9
    You will never find a USB3 drive even with a PCIe SSD inside (such as the new OWC Envoy drives) offering more than about 420 MB/sec, because of the limitations of the chipsets available.

    As far as this question of USB3 HDDs, the typical range is 100-150MB/sec as Westrock stated.
     
  10. ColdCase, Mar 8, 2015
    Last edited: Mar 8, 2015

    ColdCase macrumors 68030

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    #10
    The kind of drive the OP has is on the low end of the performance scale and his observation is consistent. To achieve 150MBps, the drive needs to be a 7200+ rmp high performance model.

    You'll never see more than 300MBps sustained real world with USB 3 and a Mac regardless of enclosure or SSD.
     
  11. matreya macrumors 65816

    matreya

    Joined:
    Nov 14, 2009
    #11
    Using BlackMagic Speed Test and an 840 EVO inside an OWC Express USB3 enclosure, I was able to get 360MB/sec... so it's possible.
     
  12. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #12
    matreya wrote above:
    [[ You will never find a USB3 drive even with a PCIe SSD inside (such as the new OWC Envoy drives) offering more than about 420 MB/sec ]]

    Benchmark performed a couple of minutes ago.
    Late 2012 Mac Mini
    Crucial m500 mounted in plugable.com "lay-flat" USB3/Sata dock

    (Note, write speed was up to 270mbps, came down slightly as read speed peaked)
     

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  13. matreya macrumors 65816

    matreya

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    Nov 14, 2009
    #13
    430MB/sec is the fastest I've seen from a SATA3 SSD connected via USB3. I have a couple of M500s setup as RAID0 inside a Thunderbay 4 mini and get 722MB/sec read, 438MB/sec write.. seems the M500s are a tad slow on write compared to other drives...
     

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