External Hard Disk copy problem

Discussion in 'Windows 7' started by nfshp253, Jun 20, 2011.

  1. nfshp253

    nfshp253 MDL Junior Member

    Aug 13, 2009
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    I have this strange problem with my laptop. Whenever I try to copy a large file to any of my 3 external hard disks (1 Maxtor, 1 Hitachi and 1 Buffalo), the speeds are tremendous for most of the process at around 70MB/s. However, all file copying gets stuck just when the copying is about to finish. Like with around 40MB left, it will stay there for around 20 seconds before actually finishing. Can anyone figure out why?
     
  2. Nimbus2000

    Nimbus2000 MDL Member

    May 5, 2010
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    This is only a guess, but I think it makes sense. Read operations are faster than writes on hard drives. It sounds like the buffer on the external disk fills and the copy process is paused until the drive can catch up.
     
  3. burfadel

    burfadel MDL EXE>MSP/CAB

    Aug 19, 2009
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    USB 3.0, USB 2.0 (most likely), or eSATA?

    If its USB 2.0, the maximum speed is around 35MB/s or so transfer. You never get the 480MBPS due to possible other traffic on the hub, but mainly because its a unidirectional connection, and to get the signalling the transfer has to stop in one direction and reverse. 70MB/s is 560MBPS, so there's no way that could be transferred over USB 2.0.

    What is happening is a data buffer is being filled, and its pausing as its waiting for that data buffer to be written. Being a USB drive, its probably set for quick removal. Once that copying is completed you can simply unplug it and all the data will be on there. If you have it set to performance, the copying won't pause at the end, but the buffer will still be writing to the disk. You should only use the safely remove device in this case.
     
  4. nfshp253

    nfshp253 MDL Junior Member

    Aug 13, 2009
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    It's only USB 2.0. And the data does get copied over. Maybe it's the buffer like all of you said. But the remaining size thing does decrease as fast as the speed indicates, which should mean it is actually copying that fast.
     
  5. cengizhan

    cengizhan MDL Senior Member

    Jul 29, 2009
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    this is normal. because the copy process reads data to buffer than writes to disk. if the buffer is large and the target drive's writing speed is low, the progressbar stays at %100 until all data in the buffer is written.