Dec 10, 2020

N-tier application in multiple Azure regions for high availability

An overview of - Running an N-tier application in multiple Azure regions for high availability

This reference architecture shows a set of proven practices for running an N-tier application in multiple Azure regions, in order to achieve availability and a robust disaster recovery infrastructure.

Key points

• Multi-region Architecture, Primary & secondary regions, provide higher availability in case of a region failure.
• Traffic Manager routes incoming requests to one of the regions. During normal operations, it routes requests to the primary region.
  
  
  • High availability
  • Scalability -
  • Elasticity - Out & In
  • Fault tolerance
  • Disaster recovery
  • Agility

Recommendations

The following recommendation is subject to your own business objectives.

A multi-region architecture can provide higher availability than deploying to a single region. If a regional outage affects the primary region, you can use Traffic Manager to fail over to the secondary region. This architecture can also help if an individual subsystem of the application fails.

There are several general approaches to achieving high availability across regions:

• Active/passive with hot standby. Traffic goes to one region, while the other waits on hot standby. Hot standby means the VMs in the secondary region are allocated and running at all times.
• Active/passive with cold standby. Traffic goes to one region, while the other waits on cold standby. Cold standby means the VMs in the secondary region are not allocated until needed for failover. This approach costs less to run, but will generally take longer to come online during a failure.
• Active/active. Both regions are active, and requests are load balanced between them. If one region becomes unavailable, it is taken out of rotation.

This reference architecture focuses on active/passive with hot standby, using Traffic Manager for failover. Note that you could deploy a small number of VMs for hot standby and then scale out as needed.

Read More
Multi-region N-tier application - Azure Architecture Center | Microsoft Docs