Cross-region replication testing expectations

Overview

Replicas and paired regions look good on slides until the first real failover. Test restores and write consistency per application tier, not just storage sync status.

Scope by service

• Storage GRS / geo-redundant: Microsoft handles replication; you still validate account failover behavior and RPO for blob queues.
• SQL geo-replication / failover groups: rehearse manual failover and connection string patterns; watch identity and secrets in secondary region.
• Active-active apps: conflict resolution and idempotency—not a storage team problem alone.

Test types

Tabletop plus timed technical run annually; smaller component tests quarterly (DNS flip, read-only DB cut).

Documentation

Runbook with decision tree (when to declare regional disaster vs transient outage), RTO per system, and comms templates. Store evidence in the compliance calendar.