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I am using Windows 7. I tried to copy five (movie) files to my Sandisk pen drive. It took 10 minutes to finish, when i was copying them individually.

When I selected the same five files as a group and then copied them to another folder of my pen drive, it took me only 5 mins.

Note that the file 's size is same each of 500 MB.

Why is this difference?

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can you repeat that experiment when starting from a fresh booted windows? as in .. boot fresh, select indivdually, measure time, reboot, select as group, measure time? – akira Aug 12 '12 at 13:14
@akira i installed windows7 last month and havent installed any software except ms office,and i m having ddr3 ram with amd x2 proceessor does hardware make diffrence? – BlueBerry - Vignesh4303 Aug 13 '12 at 2:38
i didnt ask about hw, i asked about repeating the experiment without reusing the OS-filecache (which triggers as soon as you work on files). – akira Aug 13 '12 at 6:03
@akira i tried with fresh installation at my friend's system with same hardware configuration it took me 7mins for individuals and for group it took me about 4mins,i also noted that if i add individual files the time shown for first windows is 2mins &transfer rate is 2mb/sec,and for 2nd file estimated time 5mins &1mb/sec – BlueBerry - Vignesh4303 Aug 13 '12 at 6:07
i didnt say "fresh installation" either. just reboot the system to flush away the systems IO-cache (… ). you might measure the speed of really reading the files vs getting the files from the cache (aka "ram"). also: try to measure it the other way around: first group the files, then transfer individually. also: do you batch the the individual files so the copy process runs in sequence or is the copying done in parallel (as in: you just drop the files onto the pen and 5 copy-actions are in progress at the same time)? – akira Aug 13 '12 at 6:11
up vote 1 down vote accepted

This is due to memory resources allocation. For 5 movies (2GB total), a 2 GB file swap is created; but for 1 movie (400MB) * 5 it has to created and then delete file swaps. Add additional CPU priorities.

A better way to copy would be to use TeraCopy or Roadkil's Unstoppable Copier, which bypasses the operating system and use DMA Channel (direct memory access method). Note: This applies to USB1.1/2.0 only. USB3.0 is way too fast, but no USB pen drives available (atleast for now - Aug 2012)

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any references to backup your claim that a "swap" file is created? i am also interested in a reference for that "terracopy uses dma" which makes it faster on windows7 than the built-in file-copy-mechanism (which i tend to believe is bogus)? – akira Aug 12 '12 at 13:07
@C2940680: Huh? It's August 2012 and you're saying there are no USB 3.0 pen drives available? Also, I'd love to see some hard figures about the TeraCopy/Roadkil Copier vs. Windows copy speeds as well. – Karan Aug 12 '12 at 16:29
i am using usb 2.0 ,if we clean the temp memory will it be fast before copying..?i like to mention i noted in my bios usb port transfer speed to hispeed – BlueBerry - Vignesh4303 Aug 13 '12 at 2:35

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