Earlier quoted context omitted.
Right? If you move between file system or device I would expect "move" to be impossible. At best you could copy a logical block and then delete a logical block. If you share a filesystem then perhaps a logical block is a few hundred kilobytes. If you don't then I'd expect the smallest logical block to be the file itself.
Moving on the same filesystem moves the pointer to the file.
Right! When I wrote that I made a mistake and thought that there were filesystems that used multiple drives but still had the meaningful distinction of "what drive is that file on?"
Like, yeah, RAID, several drives, one filesystem, right? Except no, because it's just one virtual device.