Recently I am encountering a problem while copying files to Pen drives. The copying as it reaches the end it stalls and continues for a long time. The problem occurs at the end of copying. Can anybody propose any solution for this. i am using Ubuntu 12.04
If it stalls there for a minute there's a good chance that nothing is wrong. I've seen a pause at that point at times myself.
While nautilus thinks it is writing to the stick, some of the data is being written to kernel managed cache. It's also possible that some of the data that the kernel has written to the stick is still being processed by the firmware on the USB stick.
When the file is closed at the very end of the copy the kernel makes sure virtually all of the data has been written. When you ask that the stick be ejected or unmounted the kernel synchronizes with the stick to make sure absolutely everything has been written. This is the reason for not just pulling out the stick without ejecting or unmounting it.
If the copy eventually start again you might try another stick to see if the problem is the media or if there is a bug in your system.
I have the same problem with Kubuntu 12.04 64bit and had it with previous versions. There is a problem with a Progress bar when transferring files to a USB memory device:
It reports that its done after just some seconds, but the files are still being copied! If I unplug a USB device - a part of the copied data is always lost! Found it as an old bug from 2006.