Let's recap. You've gone from claiming that Gluster doesn't have distributed metadata (untrue) to claiming that it copies data on rename (untrue) to claiming that renames aren't atomic across partitions (untrue because such partitions aren't even part of Gluster's architecture). Those are some very mobile goalposts. You've made similarly untrue claims about Ceph, which does have a sort of metadata partitioning but not the way you seem to think. Along the way, you've tried to redefine terms like "volume" which have well established domain specific meanings.

Such desperate attempts to disparage systems you obviously haven't even tried to understand are not helpful to users, and are insulting to people who have spent years solving hard problems to address those users' actual requirements. Believe it or not, systems exist which don't work like yours, and which prioritize different features or guarantees, and there's demonstrated demand for those differentiators. If you want to learn about those differences, to compare and contrast in ways that actually advance the state of the art, please begin. I say "begin" because I see no evidence that you've attempted such a thing. Does your academic employer know that you're misinforming students?