One of the stable FOSS program for defragging Linux/GNU driven hard drive and formatted with the common FS like ext2/3/4 is defragfs . Download and extract the zip file and copy the "defragfs" perl script file to /usr/local/bin. The command to use: cd /usr/local/bin sudo perl ./defragfs /path/you/want/defrag An example is the following defragmentation of a activated drive on my PC. Follow my blog with Bloglovin
Linux is working well