Regional recovery design
Review the dependency shared by both regions
Geographic separation does not protect against every common failure. Look for shared configuration, identity and control paths that can disable both deployments.
In this article
Trace runtime and recovery dependencies
List what each region needs to serve a request and what the operator needs to activate recovery. Compare the two lists for shared components.
A global identity dependency, common deployment artefact or central network service can remain a single failure source. Its scope may be appropriate, but the design should acknowledge it.
Distinguish a regional outage from bad configuration deployed everywhere. A second region receiving the same defect may fail at the same time as the first.
Inspect the activation path
Determine which recovery steps require creating or changing resources during the incident. Check whether those operations depend on services assumed available in the failure scenario.
Pre-provisioning some capability can reduce this dependency, but it has cost and maintenance consequences. Evaluate the actual activation sequence rather than a broad active-passive label.
Keep the runbook and required authority accessible through a path that survives the stated outage.
Review data authority and health signals
Ask what prevents both regions from accepting conflicting writes during a partition. The answer should name the supported coordination mechanism and its failure behaviour.
Inspect the health check used for routing. A shallow process check may miss a failed database or login dependency, while an overly broad check can trigger unnecessary transitions for a nonessential feature.
Define which signals justify failover and how false alarms are handled. Switching regions can itself create interruption and data consequences.
Require a relevant exercise
Test loss of the shared dependency or an equivalent safe fault in addition to a simple regional shutdown. Verify the user's task and the operator's recovery access.
Record any common failure that the design intentionally does not cover. This keeps its reliability claim aligned with evidence.
Approve the architecture when its independence is understood, its remaining shared dependencies have owners and the recovery procedure works under the chosen scenario. Two boxes on opposite sides of a diagram do not establish that independence by themselves.
Primary sources
Amazon Route 53: health checksAWS: disaster recovery strategiesReferences checked 11 September 2026.