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When I make a file transfer from HDD to pendrive(cheap sandisk USb2.0), Transfer speeds are extremely high (80-250MBps) intially and transfer indication stops(sometimes hangs) at end. It will usually become normal after sometime (It is taking same time that normally it takes in windows for complete transfer). Speeds are normal(18-22MBps) while transfering from pendrive to HDD. i have also tested using my another corsair pendrive and still the same.

laptopmodel : Asus X55C dualboot with windows 8.1

sai teja
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    It is a known bug when using ntfs on the pen drive. If you google search you will find several bug reports and suggestions as to the cause of the problem, but I have not seen a solution. http://www.google.com/search?q=ubuntu%20slow%20write%20to%20ntfs – Panther Jun 14 '15 at 14:33
  • http://ubuntuforums.org/showthread.php?t=1930429 and http://askubuntu.com/questions/165468/slow-write-speeds-to-ntfs and http://askubuntu.com/questions/237130/speeding-up-copying-between-harddrives – Panther Jun 14 '15 at 14:35

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Depending on the specific configuration of your machine, that's most likely the disk cache at work for you... Files that are being copied are transferred to the disk cache first and then in the background the kernel will copy it from the cache to disk.

To get your disk cache memory use:

free --human

and it'll give you something like:

             total       used       free     shared    buffers     cached
Mem:          3.8G       3.7G       136M       362M        13M       1.6G
-/+ buffers/cache:       2.0G       1.8G
Swap:         7.6G        57M       7.6G

In the above numbers, the cache is 1.6G, so, if no other reading/writing is going on, files copied to an external USB stick below that number will have high transfer speeds and once the cache is full, the copying will drop down to the effective speed of the USB stick...

Fabby
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