A multinational corporation uses Azure Virtual Machines to host its critical ERP system. The system requires near-zero downtime and minimal data loss in case of a regional outage. The company has a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 15 minutes. The solution must support automatic failover and failback between Azure regions. The company also requires that its disaster recovery solution be cost-optimized for inactive secondary regions, meaning resources in the secondary region should only be activated during a disaster. Which Azure service is BEST suited to meet these requirements for disaster recovery?
- AAzure Traffic Manager
- BAzure Backup for Azure VMs
- CAzure Site Recovery (ASR)
- DAzure Blob Storage Geo-Redundant Storage (GRS)
Show answer & explanationAnswer & explanation
Correct answer: C. Azure Site Recovery (ASR)
Azure Site Recovery (ASR) is designed to replicate Azure VMs between regions, providing low RPO and RTO values. It supports automatic failover and orchestrated recovery plans. Crucially, ASR is cost-optimized for disaster recovery because it only requires compute resources (VMs) in the secondary region to be provisioned and started upon failover, meaning the secondary region can remain 'cold' or 'warm' (minimal resources) until a disaster occurs, aligning with the requirement for inactive secondary regions.
Why the other options are wrong
- A. Azure Traffic Manager is a DNS-based traffic load balancer, not a disaster recovery solution for VM replication and failover with cost-optimized inactive secondary regions.
- B. Azure Backup is primarily for data protection and long-term retention, not for active-active disaster recovery with low RTO/RPO or cost-optimized inactive secondary regions.
- D. GRS provides data redundancy for storage accounts but does not provide VM replication, automatic failover for compute resources, or a mechanism for activating compute resources on demand.
ASR Cost Optimization for DR
Azure Site Recovery allows for cost-effective disaster recovery by replicating VMs to a secondary region without requiring active, running compute resources (VMs) in that region until a failover occurs.
- Only pays for storage and ASR replication costs in the secondary region normally.
- Compute costs are incurred only during test failovers or actual failovers.
- Enables 'cold' or 'warm' DR sites, reducing operational expenses.
- Still achieves low RTO/RPO for critical workloads.
Memory trick: ASR is the smart saver for DR, only paying for VMs when you need them.