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guide 03 · the foundation

Cloud

The cloud is, simply, someone else’s computers — compute, storage, and services you rent on demand over the internet instead of buying and running your own. You pay for what you use, scale in minutes, and let a provider handle the data center.

AWS Azure Google Cloud on-demand
bdcc — provision
$ cloud up --scale auto
# requesting capacity…
12 servers online in 47s
storage 5 TB attached
load balancer healthy
# traffic dropped — scaling down
9 servers released · billing paused
$
first principles

Why rent computers instead of owning them?

Owning servers means buying for your peak — and paying for idle capacity the rest of the time. The cloud flips that: capacity becomes elastic, you pay only for what you use, and the upfront capital cost (CapEx) turns into a flexible operating cost (OpEx).

Elastic scale

Add or remove capacity in minutes to match real demand.

$
Pay-as-you-go

No big upfront purchase; cost tracks usage.

Managed services

Databases, AI, networking — ready to use, no setup.

The catch: elastic doesn’t mean cheap by default. Without governance, cloud bills balloon — which is why cost optimization is a discipline of its own, not an afterthought.

the service models

How much do you want to manage?

The big three cloud models differ by where the handoff is — how much of the stack you run versus the provider. Switch models and watch the line move.

you manage provider manages
where it lives

Public, private, hybrid & multi-cloud

A separate question from service model: whose infrastructure, and how many?

Public cloud

Shared infrastructure run by a provider (AWS, Azure, GCP), rented by many customers. Maximum elasticity and the lowest barrier to entry. Best for variable workloads and speed.

Private cloud

Cloud-style infrastructure dedicated to a single organization — in your own data center or hosted. More control and isolation for strict compliance or data-residency needs, at higher cost.

Hybrid cloud

A deliberate mix of public and private, connected together. Keep sensitive workloads private, burst to public for scale. The most common enterprise reality.

Multi-cloud

Using more than one public provider — for resilience, to avoid vendor lock-in, or to use each provider’s best service. Powerful, but adds real operational complexity.

getting there

Migration: the strategies

Moving to the cloud isn’t one move. These are the common “R” strategies, from least to most effort. Expand each.

Move applications as-is onto cloud servers. Fastest and lowest-risk, but you don’t yet gain cloud-native benefits. A common, sensible first step.

Make a few cloud optimizations during the move — e.g. swap a self-run database for a managed one — without rewriting the app. A balanced effort-to-payoff ratio.

Redesign the application to be cloud-native (containers, serverless, microservices). The most effort and the biggest long-term payoff in scale and cost efficiency.

Not everything should move. Retire what’s no longer needed, and retain on-premises whatever genuinely belongs there (latency, compliance, or cost reasons). A good migration deletes as much as it moves.

try it

Own vs. rent: a rough model

The economics flip depending on how steady your workload is. Steady and predictable favors owning; spiky and variable favors cloud. Model it below.

On-prem must buy for peak; cloud scales to average. On-prem modeled at ~$6,000 / server amortized over 36 months plus power & admin; cloud at ~$0.20 / server-hour. A simplified illustration, not a quote.

On-prem (buy for peak)
Cloud (pay for average)
Better fit here
Why
knowledge check

Test yourself

Four questions on cloud fundamentals.

put it to work

Migrating, optimizing, or just trying to read the bill?

Migration and landing zones, cost optimization, and 24/7 managed operations across AWS, Azure & Google CloudRHC Solutions has engineered and operated cloud infrastructure for regulated, high-uptime enterprises since 1994.

Next guide → AI: turning data into decisions