Although Linux file systems don’t need defragmentation as much or as often as their Windows counterparts, there’s still a possibility that fragmentation may occur. It could happen if the hard drive is too small for the file system to leave enough space between the files.
How do I defrag a drive in Linux?
If you actually need to defragment a file system, the simplest way is probably the most reliable: Copy all the files off the partition, erase the files from the partition, then copy the files back onto the partition. The file system will intelligently allocate the files as you copy them back onto the disk.
Does Ubuntu need defragging?
The simple answer is that you don’t need to defrag a Linux box.