Node connectivity diagram

[tkphd]

This Issue was broken out of #79.

@Sabryr proposed that we

Elaborate more on, availability of common storage, place in one location and access from any worker node (much faster than through internet). A diagram to show all compute nodes are connected to each other and to the common storage.

[tkphd]

This is discussed, to some extent, in the Nodes section, though a diagram might help to clarify. It might also be a distraction. A generic diagram would set the login node, compute nodes, and auxiliary (storage) nodes all plugged into a switch, which is plugged into a router, which connects to the Internet. This is not how clusters are necessarily configured, though: separate login, compute, and storage networks are common, with firewalls at various choke points. It's unclear what level of fidelity such a diagram should have to help learners understand.

[tkphd]

Ah, this can be done relatively easily using CodiMD's support for nwdiag via PlantUML. Cool!

Basic example: https://codimd.carpentries.org/I5e7iXMCQdawplB_Hqhm0Q?both

The workflow, however, would be tedious. Kramdown does not provide this support; there is a Jekyll plugin to provide it, but GitHub only allows a select few plugins for security, so the site wouldn't build from the code. Instead, we'd need to generate the network diagram on CodiMD or locally, then check in the resulting image file. Not terrible, just a lot of needless manual intervention.

[tkphd]

Hmm, illustrating Internet vs. Ethernet vs. InfiniBand gets trickier. Can be done with labels, but not sure nwdiag provides enough flexibility to represent it visually.