I use Debian wheezy with KDE4. Most of the time when I copy something to a flashdrive, the write does not actually take place until I unmount. This even happens with relatively large amounts of data ...
I work in two PCs and I sync all my files from my primary PC to a USB flash memory. In my second PC, I mount the USB flash memory to the same path to work on my files as I were on my primary PC. Now ...