> Honestly, I'm terribly confused why all filesystems haven't been broken into these two easily-separable layers. Is it just inertia They are. Pretty much

> Honestly, I'm terribly confused why all filesystems haven't been broken into these two easily-separable layers. Is it just inertia They are. Pretty much all operating systems provides a block layer, on top of which filesystems are normally layered. Though the block layer isn't content addressed, it's just indexed (store block number 55, read block number 9. etc.)