The Secret Life of AWS: The Map of the World
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Exploring regions, availability zones, and the physical reality behind the screen
Author's Note: Welcome to The Secret Life of AWS, a series where we demystify cloud computing through the allegory of a vast, Victorian library. Join our librarians, Margaret and Timothy, as they navigate its halls to uncover how the Cloud actually works. In Part 1, we start with the map...
Timothy stood before the massive globe in the center of the Reading Room, spinning it with a little more force than was strictly necessary.
“It’s floating,” he said, stopping the globe with a finger on the Atlantic Ocean.
Margaret looked up from her ledger, peering over her spectacles. “I assure you, Timothy, the globe is firmly bolted to the floor.”
“Not the globe. The Cloud,” Timothy said, waving a hand vaguely at the ceiling. “Everyone says our data is ‘in the Cloud.’ It sounds so… ethereal. Like it’s just floating around in the sky, drifting wherever the wind blows.”
Margaret closed her ledger with a sharp thud. “That, Timothy, is a lie we tell people so they don’t worry about the electricity bill. The Cloud is not floating. It is heavy. It is made of concrete, steel, and thousands of miles of copper wire buried under the mud. And it certainly does not drift.”
She walked over to the globe. “If you are going to build anything in this library, you must first understand the geography of the Empire.”
“The Empire?” Timothy asked.
“The Cloud Empire,” Margaret corrected. “The domain of AWS. It spans the entire world, but it follows very strict rules of geography.”
The Major Branches (Regions)
“Imagine,” Margaret said, tapping a spot on the globe, “that this library here in London is full. Completely packed. Or perhaps, heaven forbid, it burns down.”
Timothy paled. “Don't say that.”
“It happens. Fires, floods, power outages. If we only exist in London, we are vulnerable. That is why we have Regions.”
Margaret spun the globe. “We have another major library in Virginia. Another in Frankfurt. Another in Tokyo. These are not small outposts; they are massive fortress-complexes, entirely independent of one another.”
In AWS terms, a Region is a separate geographic area. Each Region is designed to be completely isolated from the others. This achieves the greatest possible fault tolerance and stability.
- US-East-1 (N. Virginia)
- EU-West-2 (London)
- AP-Northeast-1 (Tokyo)
“When you decide to store a book—or launch a server,” Margaret explained, “you must choose a Region. You don't just put it ‘in the Cloud.’ You put it in London or Virginia. The laws of physics still apply, Timothy. If your users are in London, but you put your data in Tokyo, the information has to travel halfway around the world. That takes time. We call that Latency.”
The Separate Wings (Availability Zones)
Timothy nodded. “Okay. So I choose the London Region. I put my application in the London Library. I’m safe.”
“Not yet,” Margaret corrected. “What if the generator in the basement of the London Library explodes?”
“You are very morbid today, Margaret.”
“I am an Architect; I plan for disaster,” she replied. “This is why every Region is split into Availability Zones (AZs).”
She drew a diagram on a piece of parchment.
“Think of the London Region not as one building, but as a cluster of buildings. We have the North Wing, the South Wing, and the West Wing. They are close enough to talk to each other instantly (low latency), but far enough apart that if a fire destroys the North Wing, the South Wing is unaffected. They have different power grids, different water supplies, and different flood plains.”
The Lesson: Never put all your servers in one AZ. If you launch one instance in eu-west-2a (North Wing), you must launch a backup in eu-west-2b (South Wing). That is the secret to immortality.
The Newsstands (Edge Locations)
“That sounds expensive,” Timothy muttered. “Building massive libraries everywhere.”
“It is,” Margaret agreed. “But sometimes, you don't need a whole library. Sometimes, you just need a newsstand.”
She pointed to a tiny dot on the map. “This is a CloudFront Edge Location. It’s not a library. It’s a small kiosk at the railway station in Manchester. We don't keep the Rare Books there. We only keep copies of today’s newspaper and the most popular novels.”
Edge Locations (used by Amazon CloudFront) are a global network of servers that cache content closer to the user.
- If a user in Manchester wants to read a file stored in London, they have to fetch it from the main library.
- But if 1,000 people in Manchester want that same file, AWS sends a copy to the Manchester Edge Location. The next time someone asks for it, they get it instantly from the kiosk, without traveling to London.
The Reality of the Cloud
Timothy looked back at the globe. The vague, fluffy concept of "The Cloud" had vanished. In its place was a map of fortresses, connected by high-speed cables, guarded against disaster by redundancy.
“So,” Timothy said, “it’s not magic. It’s logistics.”
“Precisely,” Margaret smiled, polishing her glasses. “And now that you know where the libraries are, Timothy, tomorrow we shall talk about who is allowed to hold the keys.”
Aaron Rose is a software engineer and technology writer at tech-reader.blog and the author of Think Like a Genius.
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