I just had to rename a large directory inside /root in FossaDog. Renaming is usually an instantaneous operation, but this one took a loooooong time... I could see it was performing a full copy operation, as if I was moving it to another file system.
I did it again with a slightly smaller directory, but also large. Again, a looong time...
Running 'sync' after each operation also takes a looong time...
Why?