internal hard drive to external USB 2.0 hard drive at over 200 MB/second

Discussion in 'Mac Pro' started by bluesteel, Sep 24, 2011.

  1. bluesteel macrumors 6502

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    #1
    something strange but cool has happened this evening. i'm working in Windows 7 Boot Camp on my Mac Pro. i'm working on a project, and for my own peace of mind and security, i'm backing up my project folder from an internal hard drive (WD Caviar Black 2TB 64MB Cache) to an external hard drive (2.5" Toshiba 5400RPM USB 2.0) about every half an hour. all i'm doing is dragging over a roughly 2.8GB folder from the internal hard drive to the external USB 2.0 drive. at first the transfer speed was about 50MB/second, and then after a few hours i noticed that the transfer speeds where in excess of 120MB/second....and now i'm seeing 200+MB/second!!! the 2.8GB file is being transferred over to the external hard drive in in what seems like 5-7 seconds!!

    i've never seen these kind of speeds transferring data to an external USB 2.0 hard drive. how is this possible?
     
  2. derbothaus macrumors 601

    derbothaus

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    Jul 17, 2010
    #2
    It is not. What are you using to view transfer speed?
    Internal cache perhaps? It is not even theoretically possible as USB 2.0's transfer rate can't exceed 60MB/s.
    But, you know, my SuperDuper smart updates get somewhere in the range of 3,200MB/s on good day's:rolleyes:
    That's the "estimated" performance.
     
  3. bluesteel, Sep 25, 2011
    Last edited: Sep 25, 2011

    bluesteel thread starter macrumors 6502

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    #3
    it happened....it happened like 20 times in a row. i was watching the Windows 7 dialog box as it transferred. it was reading 200+ MB/second. the kicker is how fast in terms of time it was transferring that 2.8GB folder. it was transferred in like about 5 seconds..and i checked to make sure the entire contents of the folder transferred right when it was done. before i transferred it, i made sure i emptied the trash of the folder so there was no trace of it on the computer.

    earlier this morning the speeds were hitting 650+ MB/second. i just saw it hit 1.93 GB/second about 10 minutes ago. right now i'm testing the exact same scenario and its hitting 1.95 GB/second...its transferring the folder in like 2 seconds!!! i just created a video of it and am uploading to youtube...

    here is the link: http://www.youtube.com/watch?v=F1VCadZLbXs

    someone please explain explain this...lol. i don't understand :)
     
  4. derbothaus macrumors 601

    derbothaus

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    #4
    :eek::D

    Nothing you've described should be able to do this unless cache or memory is involved or you are lying on interconnects (Not saying you are btw). SSD internal 3.0Gb/s to 5400PM 2.5" via USB? Maybe you've unlocked space time continuum.
     
  5. bluesteel thread starter macrumors 6502

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    #5
    haha!!


    i agree. i'm just wondering how this works, though. not sure if you looked at the video...its pretty cut and dry. 1.95 GB/second. anyone know exactly why i get these speeds? i'm just trying to understand.
     
  6. philipma1957 macrumors 603

    philipma1957

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    #6
    try it with a 50gb file if it does the file in 10 minutes via usb then you are on to something. A 2.8gb is to small to measure well.
     
  7. Inconsequential macrumors 68000

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    Sep 12, 2007
    #7
    USB2 can't transfer over 480MBits/8 = 60MB/sec.

    Then you have overheads and what-not, 45MB/sec is the very most i've ever managed.

    So no, you are not getting 200MB/sec.

    VMWare caches some hard-disk IO so that is almost certainly where some of that performance is coming from.

    If you look in Resource monitor or whatever it is in Windows I think you'll find you are reading/writing at around 30,000,000 bytes a second...
     
  8. bluesteel, Sep 25, 2011
    Last edited: Sep 25, 2011

    bluesteel thread starter macrumors 6502

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    #8
    ok, i think i know whats going on here, and its pretty cool actually. and its something that i have never experienced in OSX. i guess Windows is caching the files that i transfer so that when i have to transfer the same file again with small changes, it moves A LOT faster??

    i tried a 49.6GB file and it started out transferring at roughly 120 MB/second for about 4GB. the speed slowly dwindled down to 28 MB/second at about 18GB in.

    i then deleted the file and emptied the Recycle Bin. i initiated a second transfer and the speed stayed at around 130 MB/second up to around 12GB and then slowly dwindled.

    i deleted the file again and emptied the Recycle Bin. i initiated a third transfer and the speeds started out at around 550 MB/second for about 8GB and then slowly moved down from there.

    ----------

    i know i'm getting over 200 MB/second because i can time it. i'm actually getting much, much faster speeds than that. but i think its because the folder i'm transferring over and over again is being cached in memory even though i'm deleting it from the trash. and somehow windows is giving me bogus transfer speed numbers....

    i'm not using VMware....i'm using boot camp.
     
  9. Inconsequential macrumors 68000

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    Sep 12, 2007
    #9
    Sorry. Fair enough.

    But your still not getting more than 40-45MB/sec over USB.

    Technology doesn't just suddenly get faster.

    Windows is peculiar in how it calculates the transfer rates :/
     
  10. bluesteel thread starter macrumors 6502

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    #10
    your 100% correct. i'm laughing at myself right now because for a second i actually thought i broke the laws of physics there....hahaha...lol!!!!! the guys at work will think this is funny :)
     
  11. InuNacho macrumors 65816

    InuNacho

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    #11
    It's Black Magic. Abuse it to long and you're Pro and all it's drives will be corrupted by it's power turning it into a dark machine of evil.
     
  12. CaptainChunk macrumors 68020

    CaptainChunk

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    #12
    I've found that the way Windows 7 reports file transfer speeds is grossly inaccurate. It's physically impossible to get that level of throughput over a USB 2.0 connection. Not to mention, there isn't a mechanical hard drive on the planet that transfers at 200 MB/s without being part of a striped RAID.
     
  13. ActionableMango macrumors 604

    ActionableMango

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    Sep 21, 2010
    #13
    Many years ago I had this happen. The copy took seconds when it should have taken minutes. It turns out the files were corrupt though, truncated in some way, so it was no great boon.
     

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