Breakdown by hosting maybe?

[charginghawk]

Shared vs custom, maybe add documentation about how big boys do it (Acquia, Pantheon, etc), some discussion of db/server load balancing/distributed cluster

[charginghawk]

https://docs.acquia.com/cloud/arch

[charginghawk]

https://pantheon.io/how-it-works
https://pantheon.io/features/elastic-hosting