I'm looking for a tool that can give me a visual representation of my ext4 fragmentation. Something similar to how Defraggler, Puran Defrag, and many others (UltraDefrag being the best) display your disk... (most good UIs display the files in the block you're hovering your mouse over)
Is there anything related for Linux?
I want to watch my disk and see just how "unneeded" defragmentation really is.
I don't want to use e4defrag, because I'm not sure it can show me what exactly it's doing to my disk.
EDIT (2021): it would seem a similar, less popular, question has been asked 3 years before this question with suggested tools: https://unix.stackexchange.com/questions/30743/is-there-a-tool-to-visualize-a-filesystem-allocation-map-on-linux