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.
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.|
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.
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.
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|
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:
- Some services are non-regional. For information and a list of non-regional services, see Products available by region.
- Older generation virtual machines are not listed. For more information, see documentation at Previous generations of virtual machine sizes.
|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||Azure Machine Learning Studio (classic)|
|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|
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
- Create a virtual machine
- Add a Managed Disk using PowerShell
- Create a zone redundant virtual machine scale set
- Load balance VMs across zones using a Standard Load Balancer with a zone-redundant frontend
- Load balance VMs within a zone using a Standard Load Balancer with a zonal frontend
- Zone-redundant storage
- SQL Database general purpose tier
- Event Hubs geo-disaster recovery
- Service Bus geo-disaster recovery
- Create a zone-redundant virtual network gateway
- Add zone redundant region for Azure Cosmos DB
- Getting Started Azure Cache for Redis Availability Zones
- Create an Azure Active Directory Domain Services instance
- Create an Azure Kubernetes Service (AKS) cluster that uses Availability Zones