Executive Summary

This report provides a detailed technical analysis of the disaster recovery (DR) capabilities for on-premises virtual machines replicated to Azure using Azure Site Recovery (ASR) with a Geo-Redundant Storage (GRS) vault. The central question: **is it possible to failover to a secondary Azure region if both the on-prem datacenter and the primary Azure region go down?**

The short answer is **no**. The current configuration, relying solely on ASR with GRS, does not provide an automatic or user-initiated failover capability to the secondary region. This report details why and presents the Microsoft-recommended solution for true cross-region DR.

Section 1: The Current Configuration Explained

1.1 The Role of Azure Site Recovery (ASR)

Azure Site Recovery is primarily an orchestration engine. It manages the replication of on-premises machines to Azure Storage and, in a disaster, uses that data to build and run new Azure VMs. Its value is in automating the entire DR lifecycle, from replication to failover and failback.

1.2 Deconstructing the Recovery Services Vault and GRS

The Recovery Services Vault is a management entity in a specific Azure region. It stores metadata and configuration, but not the bulk VM disk data. Geo-Redundant Storage (GRS) is a data durability option that asynchronously replicates your storage data to a secondary, paired Azure region. Its purpose is to ensure a copy of the data survives a regional outage.

1.3 Critical Limitation: GRS Data Accessibility

This is the core of the issue. A standard GRS configuration does not automatically provide read or write access to the data in the secondary region. The official Azure documentation is clear: access is only granted after a formal, Microsoft-initiated regional failover. The customer has no control over this process and there is no SLA for its execution.

Section 2: Why Secondary Region Failover is Infeasible

It is not possible to initiate a failover to the secondary region with the current architecture if the primary Azure region is unavailable. This is due to two key factors.

2.1 ASR's Dependency on the Primary Region

The ASR service itself—the control plane—runs in the primary Azure region. If that region fails, the ASR service is also down. You cannot access the vault, you cannot click "Failover", and you cannot run any recovery plans. The tool you need to orchestrate recovery is lost in the disaster.

2.2 ASR Failover vs. Azure Backup's Cross-Region Restore (CRR)

It's vital not to confuse ASR with a different service: Azure Backup with Cross-Region Restore (CRR). CRR *does* allow user-initiated restores to a secondary region. However, it's a backup service, not a DR service. The differences are stark:

Section 3: Recommended Architecture: True Cross-Region DR

The definitive solution is a two-stage recovery model. This extends the existing DR plan, transforming it into a multi-stage strategy that effectively mitigates the risk of a dual outage.

3.1 Implementing Azure-to-Azure Site Recovery

This is a native capability within ASR designed for replicating Azure VMs from one region to another. It is the industry-standard, Microsoft-recommended approach. By implementing it, you move from dependency to complete control, with a user-initiated failover available on demand.

Conclusion and Final Recommendations

The reliance on GRS for failover capability is a fundamental misapplication of the technology. The definitive solution is to evolve the current BCDR strategy into a two-stage recovery model by implementing Azure-to-Azure Site Recovery. This architecture provides full user control, enterprise-grade performance, and provable reliability through testing. It is the strong recommendation of this report that the customer prioritize this implementation to close a significant gap in their business continuity posture.