Azure Data Centers

Azure provides more than 100 redundant & secure facilities worldwide linked with a network.
- Allows you to
  - gain global reach with local presence
  - keep your data secure and compliant with local laws
You can pick the region and sometimes availability zone you want resources deployed into.
- ❗You can’t select a specific datacenter or location within a datacenter.

Regions

Regions = Contains at least one, but often multiple datacenters that are nearby and networked together with a low-latency network.
- Azure assigns and controls the resources within each region to ensure workloads are appropriately balanced.
- E.g. West US, Canada Central, West Europe, Australia East, and Japan West.
❗Some services or virtual machine features are only available in certain regions, such as specific virtual machine sizes or storage types.
Azure regions as of February 2020:
💡Regions provide better scalability, redundancy, and preserves data residency for your services.
Read more: Azure regions

For compliance or legal purposes.
Azure Government
- US DoD Central, US Gov Virginia, US Gov Iowa and more
- 📝 Physical and logical network-isolated instances of Azure for US government agencies and partners.
China East, China North and more
- Unique partnership between Microsoft and 21Vianet
- Microsoft does not directly maintain the datacenters.

Each region belongs to a single geography
Defined by geopolitical boundaries or country borders.
Has specific service availability, compliance, and data residency/sovereignty rules applied to it
Fault-tolerant to withstand complete region failure through their connection to dedicated networking infrastructure
- 📝 Fault-tolerance: App ability to self-detect and correct all types of problems in its environment
Data residency
- Defines the legal or regulatory requirements imposed on data
- Based on the country or region in which it resides
- 💡 An important consideration when planning out your application data storage.
Geographies are broken up into the following areas
- Americas
- Europe
- Asia Pacific
- Middle East and Africa
Read more: Azure geographies

📝 Physically separate datacenters within an Azure region.
💡 Allows you to make applications highly available through redundancy.
- Replicate your compute, storage, networking, and data resources in other zones.
- Costs more
- Primarily for VMs, managed disks, load balancers, and SQL databases
- Zonal services: Pin resource to a specific zone.
- Zone-redundant services: Replicates automatically across zones.
Have independent power, cooling, and networking
Set up to be an isolation boundary
- If one zone goes down, the other continues working
Identified as 1-2-3
- Logically mapped to the actual physical zones for each subscription independently.
- Availability Zone 1 in a given subscription might refer to a different physical zone than Availability Zone 1 in a different subscription.
Connected through high-speed, private fiber-optic networks.
❗There are regions that do not support (multiple) availability zones

Each Azure region is always paired with another region within the same geography
- E.g. West US paired with East US, and South East Asia paired with East Asia
Pairs are at least 300 (≈ 500 km) miles away.
Allows for the replication of resources, e.g. virtual machine storage
- Some services offer automatic geo-redundant storage using region pairs.
Reduce the likelihood of interruptions to both regions
- E.g. natural disasters, civil unrest, power outages, or physical network outages
If one region fails, services automatically fail over to the other region in its region pair.
Data continues to reside within the same geography as its pair (except for Brazil South) for tax and law enforcement jurisdiction purposes.
If there’s an extensive Azure outage =>
- One region out of every pair is prioritized to make sure at least one is restored as quick as possible,
Planned Azure updates are rolled out to paired regions one region at a time to minimize downtime and risk of application outage.