Each Azure region is paired with another region within the same geography, together making a regional pair. The exception is Brazil South, which is paired with a region outside its geography.
Figure 1 – Azure regional pair diagram
|Asia||East Asia||Southeast Asia|
|Australia||Australia East||Australia Southeast|
|Canada||Canada Central||Canada East|
|China||China North||China East|
|India||Central India||South India|
|Japan||Japan East||Japan West|
|Korea||Korea Central||Korea South|
|North America||North Central US||South Central US|
|North America||East US||West US|
|North America||East US 2||Central US|
|North America||West US 2||West Central US|
|Europe||North Europe||West Europe|
|Japan||Japan East||Japan West|
|Brazil||Brazil South (1)||South Central US|
|US Government||US Gov Iowa||US Gov Virginia|
|US Government||US Gov Arizona||US Gov Texas|
|US Department of Defense||US DoD East||US DoD Central|
|UK||UK West||UK South|
|Germany||Germany Central||Germany Northeast|
Table 1 – Mapping of Azure regional pairs
An example of paired regions
Figure 2 below shows a hypothetical application which uses the regional pair for disaster recovery. The green numbers highlight the cross-region activities of three Azure services (Azure compute, storage, and database) and how they are configured to replicate across regions. The unique benefits of deploying across paired regions are highlighted by the orange numbers.
Figure 2 – Hypothetical Azure regional pair
1. Azure Compute (PaaS) – You must provision additional compute resources in advance to ensure resources are available in another region during a disaster.
2. Azure Storage – Geo-Redundant storage (GRS) is configured by default when an Azure Storage account is created. With GRS, your data is automatically replicated three times within the primary region, and three times in the paired region.
3. Azure SQL Databases – With Azure SQL Standard Geo-Replication, you can configure asynchronous replication of transactions to a paired region. With premium geo-replication, you can configure replication to any region in the world; however, we recommend you deploy these resources in a paired region for most disaster recovery scenarios.
4. Azure Resource Manager – Resource Manager inherently provides logical isolation of service management components across regions. This means logical failures in one region are less likely to impact another.
Benefits of paired regions
5. Physical isolation – When possible, Azure prefers at least 300 miles of separation between datacenters in a regional pair, although this isn’t practical or possible in all geographies. Physical datacenter separation reduces the likelihood of natural disasters, civil unrest, power outages, or physical network outages affecting both regions at once. Isolation is subject to the constraints within the geography (geography size, power/network infrastructure availability, regulations, etc.).
6. Platform-provided replication – Some services such as Geo-Redundant Storage provide automatic replication to the paired region.
7. Region recovery order – In the event of a broad outage, recovery of one region is prioritized out of every pair. Applications that are deployed across paired regions are guaranteed to have one of the regions recovered with priority. If an application is deployed across regions that are not paired, recovery may be delayed – in the worst case the chosen regions may be the last two to be recovered.
8. Sequential updates – Planned Azure system updates are rolled out to paired regions sequentially (not at the same time) to minimize downtime, the effect of bugs, and logical failures in the rare event of a bad update.
9. Data residency – A region resides within the same geography as its pair (with the exception of Brazil South) in order to meet data residency requirements for tax and law enforcement jurisdiction purposes.
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