Although we now have shared storage for our persistent container data, our docker nodes don't share any other docker data, such as container images. This results in an inefficiency - every node which participates in the swarm will, at some point, need the docker image for every container deployed in the swarm.
This is a companion discussion topic for the original entry at https://geek-cookbook.funkypenguin.co.nz/ha-docker-swarm/registry/