Azure Services that support Availability Zones

• 01/26/2021
• 6 minutes to read
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Microsoft Azure global infrastructure is designed and constructed at every layer to deliver the highest levels of redundancy and resiliency to its customers. Azure infrastructure is composed of geographies, regions, and Availability Zones, which limit the blast radius of a failure and therefore limit potential impact to customer applications and data. The Azure Availability Zones construct was developed to provide a software and networking solution to protect against datacenter failures and to provide increased high availability (HA) to our customers.

Availability Zones are unique physical locations within an Azure region. Each zone is made up of one or more datacenters with independent power, cooling, and networking. The physical separation of Availability Zones within a region limits the impact to applications and data from zone failures, such as large-scale flooding, major storms and superstorms, and other events that could disrupt site access, safe passage, extended utilities uptime, and the availability of resources. Availability Zones and their associated datacenters are designed such that if one zone is compromised, the services, capacity, and availability are supported by the other Availability Zones in the region.

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 a 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.

Azure services supporting Availability Zones fall into three categories: zonal, zone-redundant, and non-regional services. Customer workloads can be categorized to utilize any of these architecture scenarios to meet application performance and durability.

• Zonal services – A resource can be deployed to a specific, self-selected Availability Zone to achieve more stringent latency or performance requirements. Resiliency is self-architected by replicating applications and data to one or more zones within the region. Resources can be pinned to a specific zone. For example, virtual machines, managed disks, or standard IP addresses can be pinned to a specific zone, which allows for increased resilience by having one or more instances of resources spread across zones.

• Zone-redundant services – Azure platform replicates the resource and data across zones. Microsoft manages the delivery of high availability since Azure automatically replicates and distributes instances within the region. ZRS, for example, replicates the data across three zones so that a zone failure does not impact the HA of the data.

• Non-regional services – Services are always available from Azure geographies and are resilient to zone-wide outages as well as region-wide outages.

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. To learn more, read building solutions for high availability using Availability Zones.

Azure services supporting Availability Zones

• The older generation virtual machines are not listed. For more information, see Previous generations of virtual machine sizes.
• As mentioned in the Regions and Availability Zones in Azure, some services are non-regional. These services do not have dependency on a specific Azure region, as such are resilient to zone-wide outages as well as region-wide outages. The list of non-regional services can be found at Products available by region.

Azure regions with Availability Zones

* To learn more about Availability Zones and available services support in these regions, contact your Microsoft sales or customer representative. For the upcoming regions that will support Availability Zones, see Azure geographies.

Azure Services supporting Availability Zones

• Older generation virtual machines are not listed below. For more information, see previous generations of virtual machine sizes.

• Some services are non-regional, see Regions and Availability Zones in Azure for more information. These services do not have dependency on a specific Azure region, making them resilient to zone-wide outages and region-wide outages. The list of non-regional services can be found at Products available by region.

Zone Resilient Services

🌐 Non-Regional Services - Services are always available from Azure geographies and are resilient to zone-wide outages as well as region-wide outages.

🔷 Resilient to the zone-wide outages

Foundational Services

Mainstream services

Non-regional

Pricing for VMs in Availability Zones

There is no additional cost for virtual machines deployed in an Availability Zone. 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

Next steps