1) When Docker Swarm containers access files from outside their containers, it uses NFS. This isn't a problem if our database files live in the container, but we want our databases to live on persistent storage (ideally, something separate even from the cloud instance, like a block storage device). That means that we can't guarantee that the databases will be on the same instance as the database container. Our database would then have to make network file system requests to read and write from the database. This problem isn't especially difficult to solve, but it's not really worth solving for our purposes; The up-front investment of time places it outside the scope of this guide, because...