Regions and Availability Zones in Azure

Microsoft Azure services are available globally to drive your cloud operations at an optimal level. You can choose the best region for your needs based on technical and regulatory considerations: service capabilities, data residency, compliance requirements, and latency.

Terminology

To better understand regions and Availability Zones in Azure, it helps to understand key terms or concepts.

Term or concept Description
region A set of datacenters deployed within a latency-defined perimeter and connected through a dedicated regional low-latency network.
geography An area of the world containing at least one Azure region. Geographies define a discrete market that preserve data residency and compliance boundaries. Geographies allow customers with specific data-residency and compliance needs to keep their data and applications close. Geographies are fault-tolerant to withstand complete region failure through their connection to our dedicated high-capacity networking infrastructure.
Availability Zone Unique physical locations within a region. Each zone is made up of one or more datacenters equipped with independent power, cooling, and networking.
recommended region A region that provides the broadest range of service capabilities and is designed to support Availability Zones now, or in the future. These are designated in the Azure portal as Recommended.
alternate (other) region A region that extends Azure's footprint within a data residency boundary where a recommended region also exists. Alternate regions help to optimize latency and provide a second region for disaster recovery needs. They are not designed to support Availability Zones (although Azure conducts regular assessment of these regions to determine if they should become recommended regions). These are designated in the Azure portal as Other.
foundational service A core Azure service that is available in all regions when the region is generally available.
mainstream service An Azure service that is available in all recommended regions within 12 months of the region/service general availability or demand-driven availability in alternate regions.
specialized service An Azure service that is demand-driven availability across regions backed by customized/specialized hardware.
regional service An Azure service that is deployed regionally and enables the customer to specify the region into which the service will be deployed. For a complete list, see Products available by region.
non-regional service An Azure service for which there is no dependency on a specific Azure region. Non-regional services are deployed to two or more regions and if there is a regional failure, the instance of the service in another region continues servicing customers. For a complete list, see Products available by region.

Regions

A region is a set of datacenters deployed within a latency-defined perimeter and connected through a dedicated regional low-latency network. Azure gives you the flexibility to deploy applications where you need to, including across multiple regions to deliver cross-region resiliency. For more information, see Overview of the resiliency pillar.

Availability Zones

An Availability Zone is a high-availability offering that protects your applications and data from datacenter failures. Availability Zones are unique physical locations within an Azure region. Each zone is made up of one or more datacenters equipped with independent power, cooling, and networking. To ensure resiliency, there's a minimum of three separate zones in all enabled regions. The physical separation of Availability Zones within a region protects applications and data from datacenter failures. Zone-redundant services replicate your applications and data across Availability Zones to protect from single-points-of-failure. With Availability Zones, Azure offers industry best 99.99% VM uptime SLA. The full Azure SLA explains the guaranteed availability of Azure as a whole.

An Availability Zone in an Azure region is a combination of a fault domain and an update domain. For example, if you create three or more VMs across three zones in an Azure region, your VMs are effectively distributed across three fault domains and three update domains. The Azure platform recognizes this distribution across update domains to make sure that VMs in different zones are not scheduled to be updated at the same time.

Build high-availability into your application architecture by co-locating your compute, storage, networking, and data resources within a zone and replicating in other zones. Azure services that support Availability Zones fall into two categories:

  • Zonal services – where a resource is pinned to a specific zone (for example, virtual machines, managed disks, Standard IP addresses), or
  • Zone-redundant services – when the Azure platform replicates automatically across zones (for example, zone-redundant storage, SQL Database).

To achieve comprehensive business continuity on Azure, build your application architecture using the combination of Availability Zones with Azure region pairs. You can synchronously replicate your applications and data using Availability Zones within an Azure region for high-availability and asynchronously replicate across Azure regions for disaster recovery protection.

conceptual view of one zone going down in a region

Important

The Availability Zone identifiers (the numbers 1, 2 and 3 in the picture above) are logically mapped to the actual physical zones for each subscription independently. That means that Availability Zone 1 in a given subscription might refer to a different physical zone than Availability Zone 1 in a different subscription. As a consequence, it's recommended to not rely on Availability Zone IDs across different subscriptions for virtual machine placement.

Region and service categories

Azure's approach on availability of Azure services across regions is best described by expressing services made available in recommended regions and alternate regions.

  • Recommended region - A region that provides the broadest range of service capabilities and is designed to support Availability Zones now, or in the future. These are designated in the Azure portal as Recommended.
  • Alternate (other) region - A region that extends Azure's footprint within a data residency boundary where a recommended region also exists. Alternate regions help to optimize latency and provide a second region for disaster recovery needs. They are not designed to support Availability Zones (although Azure conducts regular assessment of these regions to determine if they should become recommended regions). These are designated in the Azure portal as Other.

Comparing region types

Azure services are grouped into three categories: foundational, mainstream, and specialized services. Azure's general policy on deploying services into any given region is primarily driven by region type, service categories, and customer demand:

  • Foundational – Available in all recommended and alternate regions when the region is generally available, or within 12 months of a new foundational service becoming generally available.
  • Mainstream – Available in all recommended regions within 12 months of the region/service general availability; demand-driven in alternate regions (many are already deployed into a large subset of alternate regions).
  • Specialized – Targeted service offerings, often industry-focused or backed by customized/specialized hardware. Demand-driven availability across regions (many are already deployed into a large subset of recommended regions).

To see which services are deployed in a given region, as well as the future roadmap for preview or general availability of services in a region, see Products available by region.

If a service offering is not available in a specific region, you can share your interest by contacting your Microsoft sales representative.

Region type Non-regional Foundational Mainstream Specialized Availability Zones Data residency
Recommended ✔️ ✔️ ✔️ Demand-driven ✔️ ✔️
Alternate ✔️ ✔️ Demand-driven Demand-driven N/A ✔️

Services by category

As mentioned previously, Azure classifies services into three categories: foundational, mainstream, and specialized. Service categories are assigned at general availability. Often, services start their lifecycle as a specialized service and as demand and utilization increases may be promoted to mainstream or foundational. The following table lists the category for services as foundational, mainstream, or specialized. You should note the following about the table:

Foundational Mainstream Specialized
Account Storage API Management Azure API for FHIR
Application Gateway App Configuration Azure Analysis Services
Azure Backup App Service Azure Blockchain Service
Azure Cosmos DB Automation Azure Blueprints
Azure Data Lake Storage Gen2 Azure Active Directory Domain Services Azure Database for MariaDB
Azure ExpressRoute Azure Bastion Azure Dedicated HSM
Azure SQL Database Azure Cache for Redis Azure Dev Spaces
Cloud Services Azure Cognitive Search Azure Digital Twins
Cloud Services: Av2-Series Azure Data Explorer Azure Lab Services
Cloud Services: Dv2-Series Azure Data Share Azure NetApp Files
Cloud Services: Dv3-Series Azure Database for MySQL Azure Quantum
Cloud Services: Ev3-Series Azure Database for PostgreSQL Azure Spring Cloud Service
Cloud Services: Instance Level IPs Azure Database Migration Service Azure Time Series Insights
Cloud Services: Reserved IP Azure Databricks Azure VMware Solution by CloudSimple
Disk Storage Azure DDoS Protection Cloud Services: G-Series
Event Hubs Azure DevTest Labs Cloud Services: H-Series
Key Vault Azure Firewall Cognitive Services : Custom Vision
Load balancer Azure Firewall Manager Cognitive Services : Speaker Recognition
Service Bus Azure Functions Data Box Heavy
Service Fabric Azure HPC Cache Data Catalog
Virtual Machine Scale Sets Azure IoT Hub Data Factory : Data Factory V1
Virtual Machines Azure Kubernetes Service (AKS) Data Lake Analytics
Virtual Machines: Av2-Series Azure Machine Learning Machine Learning Studio
Virtual Machines: Bs-Series Azure Private Link Microsoft Genomics
Virtual Machines: DSv2-Series Azure Red Hat OpenShift Remote Rendering
Virtual Machines: DSv3-Series Azure SignalR Service Spatial Anchors
Virtual Machines: Dv2-Series Azure Site Recovery StorSimple
Virtual Machines: Dv3-Series Azure Stack Hub Video Indexer
Virtual Machines: ESv3-Series Azure Stream Analytics Virtual Machines: DASv4-Series
Virtual Machines: Ev3-Series Azure Synapse Analytics Virtual Machines: DAv4-Series
Virtual Machines: F-Series Batch Virtual Machines: DCsv2-series
Virtual Machines: FS-Series Cloud Services: M-series Virtual Machines: EASv4-Series
Virtual Machines: Instance Level IPs Cognitive Services Virtual Machines: EAv4-Series
Virtual Machines: Reserved IP Cognitive Services: Computer Vision Virtual Machines: G-Series
Virtual Network Cognitive Services: Content Moderator Virtual Machines: GS-Series
VPN Gateway Cognitive Services: Face Virtual Machines: HBv1-Series
Cognitive Services: Form Recognizer Virtual Machines: HBv2-Series
Cognitive Services: Language Understanding Virtual Machines: HCv1-Series
Cognitive Services: QnA Maker Virtual Machines: H-Series
Cognitive Services: Speech Services Virtual Machines: LS-Series
Container Instances Virtual Machines: LSv2-Series
Container Registry Virtual Machines: Mv2-Series
Data Factory Virtual Machines: NC-Series
Event Grid Virtual Machines: NCv2-Series
HDInsight Virtual Machines: NCv3-Series
Logic Apps Virtual Machines: NDs-Series
Media Services Virtual Machines: NDv2-Series
Network Watcher Virtual Machines: NV-Series
Notification Hubs Virtual Machines: NVv3-Series
Power BI Embedded Virtual Machines: NVv4-Series
Premium Blob Storage Virtual Machines: SAP HANA on Azure Large Instances
Premium Files Storage Visual Studio App Center
Storage: Archive Storage
Ultra Disk Storage
Virtual Machines: Ddsv4-Series
Virtual Machines: Ddv4-Series
Virtual Machines: Dsv4-Series
Virtual Machines: Dv4-Series
Virtual Machines: Edsv4-Series
Virtual Machines: Edv4-Series
Virtual Machines: Esv4-Series
Virtual Machines: Ev4-Series
Virtual Machines: Fsv2-Series
Virtual Machines: M-Series
Virtual WAN

Services resiliency

All Azure management services are architected to be resilient from region-level failures. In the spectrum of failures, one or more Availability Zone failures within a region have a smaller failure radius compared to an entire region failure. Azure can recover from a zone-level failure of management services within the region or from another Azure region. Azure performs critical maintenance one zone at a time within a region, to prevent any failures impacting customer resources deployed across Availability Zones within a region.

Pricing for VMs in Availability Zones

There is no additional cost for virtual machines deployed in an Availability Zone. 99.99% VM uptime SLA is offered when two or more VMs are deployed across two or more Availability Zones within an Azure region. There will be additional inter-Availability Zone VM-to-VM data transfer charges. For more information, review the Bandwidth pricing page.

Get started with Availability Zones

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