Lesson 1 / 25

What Azure Is and How It Is Laid Out

Explain regions, availability zones and region pairs, and pick a region for a workload.

A global set of datacentres you rent by the minute

Microsoft Azure is a public cloud: compute, storage, databases, networking and managed services that you create through an API and pay for as you use them. Physically, Azure is organised into regions (a set of datacentres in one metro area, such as Central India in Pune or West Europe in the Netherlands). Many regions have availability zones: at least three physically separate locations inside the region, each with independent power, cooling and networking. Spreading copies of a workload across zones protects you from one datacentre failing. Many regions also have a paired region in the same geography, used for platform updates that are rolled out one region of the pair at a time and for geo-replicated storage. Choosing a region is a real decision: latency to users, data-residency law, which services and VM sizes are available there, and price all differ.

From geography to zone

Think in three levels: a geography contains regions, and a region contains availability zones.

Nested shapes: a large area holding two regions, each region holding three smaller zone blocks. — Figure 1.1 — Geography, region and availability zones.

Listing regions from the CLI

The Azure CLI can tell you which regions your subscription can use. Names such as centralindia are what you pass to --location.

# sign in (opens a browser or device-code flow)
az login

# list regions available to the current subscription
az account list-locations --query "[].{name:name, display:displayName}" -o table

# check which VM sizes a region offers before you commit to it
az vm list-skus --location centralindia --resource-type virtualMachines -o table

Region choice is hard to undo

Most resources cannot be moved to another region; you recreate them and migrate data. Decide on region up front: put resources close to users, check the service is offered there, and check whether the region has availability zones before you design for zone redundancy.

Quick check: What is an availability zone?

A physically separate location inside a region with independent power, cooling and network
A paired region in another country
A billing boundary for a team
A virtual network inside a subscription

Answer

A physically separate location inside a region with independent power, cooling and network — Zones are separate datacentre locations inside one region, so a zone-redundant design survives one location failing.