Geo-replicated failover, connection strings, and front door

Question

We have a Web App that uses a SQL db. The app is copied to a secondary region and the db is replicated to that region. We also use Front Door with app failover in case a site becomes unavailable. When Front Door redirects traffic to the secondary site because SQL failure is causing app issues, does the SQL traffic automatically get redirected to the secondary db or do we have to manually modify the SQL connection string?

Answer 1

Hi @Matthew Barrett

it depends on which failover scenario you are using, Azure SQL Database also provides several business continuity features that you can use to mitigate various unplanned scenarios.

• Active geo-replication allows you to create readable replicas and manually failover to any replica in case of a regional outage.
• Auto-failover groups allow the application to automatically recover in the event of a regional outage.

The differences between both approaches as follows:

in case of Geo-replication you will have to update the connection string

also, take into considerations the RPO and RTO for both scenarios.

In this table, Manual database failover refers to failover of a single database to its geo-replicated secondary using the unplanned mode.

reference: https://learn.microsoft.com/en-us/azure/azure-sql/database/business-continuity-high-availability-disaster-recover-hadr-overview?view=azuresql

Answer 2

We are using Failover groups now, as it resolves both auto-failover and endpoint resolution.

Thank you.