disk defragmentation?
 

In Windows, it is recommended to occasionally run programs like scandisk and the disk defragmenter. Is there no need to do this with the linux native fileseystems? I think I never saw it mentioned anywhere.

You don't, Linux filesystems don't fragment that much and the fragmentation doesn't get worse over time, as with Windows. Defragging is not needed.

http://www.bellevuelinux.org/filesystem.html

Thank you very much.