[mappu]

That's an awesome diagram and quite a few servers (but latency kills the map-overlay experience, i think a static png or svg might have been better...) Interesting that servers are are either paired autoscaling over two AZs, or statically provisioned in three AZs - or am i mis-reading the diagram? Two entire mirrors for testing and staging must have become a pretty big cost.

For others outside the US confused about what the application actually does, and what the Narwhal in the testing/staging pictures refers to, this helped; http://arstechnica.com/information-technology/2012/11/built-...

[DrJ]

Looks like the AutoScaling groups are applications or stores where they do not need to coordinate their actions. The 3-az deployments seems to be APIs, which I am guessing scales with each regions (to reduce data cost?) and probably brought up/down automatically with Puppet to handle post-launch configurations. (you are reading it correctly).

I would guess testing is a skeleton version of the entire deployment so the cost is minimal and just need to test new deploys and verification for tests.

Staging probably wasn't a full mirror, at best I would venture to guess they had hot swaps coming up in staging and then being switched against production via ELBs.

They mention costs a few times in articles, so I would venture to guess they did optimize around many of those corners.