Understanding fail over and fail back in disaster recovery

Hello Handinata Tanudjaja,

Welcome to Microsoft Q&A!

Failover and Failback processes in disaster recovery. You're definitely on the right track! Here’s a    breakdown of your understanding with some clarifications:

Failover Initiation: You’ve mentioned that failover occurs when Microsoft declares a disaster in the primary region. That’s correct! The secondary region becomes primary, and the original primary becomes secondary. Just as you noted, failover cannot be initiated by customers before a disaster is declared unless Cross Region Restore is enabled.

Failback: Your understanding of failback is also spot on. It’s crucial to check the Last Sync Time before falling back to ensure data consistency and prevent data loss. You’ve identified critical aspects of both failover and failback processes confidently.  

In addition to what you've shared, here are a few key points

Data Synchronization: During failover, some data may still be written in the original primary. This can lead to synchronization issues that need to be resolved during failback.

Downtime: Failback may sometimes involve extra downtime compared to failover, due to data verification and remediation steps.

Overall, you’ve captured the high-level points quite well! If you have any specific scenarios or concerns you’d like to discuss, feel free to share.  

Hope this helps clarify things for you! If you need more details or have specific questions, you can share with us

References:

• What are business continuity, high availability, and disaster recovery?
• Common questions about Azure-to-Azure disaster recovery

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