It has a "set it and forget it" feature similar to Diskeeper, here based on "idle time" instead of "screensaver", and it can stop if the CPU goes over a certain threshold. Free, but it seems to use a little bit more of memory than DK. I think it can be recommended

defrag + visualization + allows you to set some most used files to the fastest sectors

useful tips

"a simple but powerful hard disk analyser. Using a sophisticated mix of graphs, tables and tree displays, it gives the user a complete overview of the contents of a hard disk"

"TestDisk is a powerful free data recovery software! It was primarily designed to help recover lost partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software, certain types of viruses or human error"

The Drive Scroll screen saver displays the data from a disk drive as a scrolling image. The data is directly copied to an RGB screen buffer without interpretation.