BtrFS includes "subvolumes" (a.k.a. directories), & "snapshots" using a similar encoding. And there's a BTree of all the BTrees. I'll discuss these concepts in more detail, as well as how they relate to our hypothetical string-centric hardware, over the next ~week. 1.3/1.3 Fin for today! As @nieuemma noted: I'm not entirely I sure I got my facts on what a BtrFS subvolume is. I'll double-check when I discuss proper!