1. Ask for discounts if you are a big AWS customer (e.g., spend $1mln+/year). At some point, they were huge for inter-AZ transfers.
2. Put things in one AZ. Running DB in "b" zone and your only server in "a" is even worse than just standardizing on one zone.
3. When using multiple AZ do load aware AZ balancing.
There must be use cases for this, but I lack imagination. Cost? But not cost?
Many companies run servers without considering AZ. Then you can get the "best" of the worlds:
1. Your service is down if either of AZs gets hiccups.
2. You pay network charges and latency cost.
https://docs.aws.amazon.com/ram/latest/userguide/working-wit...
But in the context of data transfer costs, this would actually increase the costs, because there's a small surcharge for Intelligent Tiering - and the only relevant storage class for sidestepping data transfer costs is standard storage (because it's the only one with free download), so Intelligent Tiering won't provide value.
https://discourse.nixos.org/t/the-nixos-foundations-call-to-...