Azure Site Recovery - Disaster Recovery as a Service

Azure Site Recovery on Microsoft Azure

What is Azure Site Recovery?

Azure Site Recovery (ASR) is Microsoft’s disaster-recovery-as-a-service solution, providing continuous replication of VMs and physical servers, orchestrated failover during outages, and failback after recovery. ASR protects workloads against datacenter outages, natural disasters, or cyberattacks by replicating to a secondary Azure region or from on-premises to Azure.

At its core, ASR distinguishes between several scenarios: Azure-to-Azure (region-to-region DR for Azure VMs), VMware-to-Azure, Hyper-V-to-Azure, and physical-server-to-Azure. For VMware and physical server scenarios, ASR now uses agent-based replication on a modernized architecture without the earlier configuration server appliance of the classic experience; the classic experience for VMware/physical server DR was retired in March 2026, so all new deployments and remaining workloads must run on the modernized architecture. For Azure VMs, replication continues to happen directly at the platform level. Recovery Point Objective (RPO) is typically in the low single-digit minutes, depending on the scenario.

Recovery plans orchestrate failover of multi-tier applications with defined boot sequences, pre- and post-scripts, and manual actions. Test failover enables regular DR drills without impacting production. Application-consistent snapshots via VSS (Windows) or custom scripts (Linux) support consistent startup of replicated VMs. After recovery, ASR supports failback to the original environment.

Core Features

• Continuous replication: Block-level replication with low RPO for Azure VMs, VMware VMs, Hyper-V VMs, and physical servers.
• Modernized VMware/physical server architecture: Agent-based replication without a separate configuration server appliance; successor to the classic experience retired in March 2026.
• Recovery plans: Orchestration of multi-tier failover with boot sequences and pre-/post-scripts.
• Test failover: DR drills in an isolated test environment without affecting production.
• Failback: Returning workloads to the original environment after recovery.
• Application-consistent snapshots: VSS support (Windows) or custom scripts (Linux) for consistent recovery.

Typical Use Cases

Azure Region-to-Region Disaster Recovery

Organizations replicate production VMs between two Azure regions for disaster recovery. If the primary region fails, they perform an orchestrated failover to the secondary region, with web tier, app tier, and DB tier starting in a defined sequence.

VMware to Azure Migration with DR Protection

Organizations migrate on-premises VMware VMs to Azure using ASR on the modernized architecture. ASR continuously replicates VMs to Azure, enables test migrations without downtime, and performs the final cutover. After migration, they use ASR for Azure-to-Azure DR.

Business Continuity for Critical Workloads

Business-critical applications (ERP, CRM, finance systems) are protected with ASR. Recovery plans define failover sequences: domain controllers and DNS first, then databases, then app servers, and finally the web frontend.

Compliance-Driven Disaster Recovery

Regulated industries (finance, healthcare, government) need documented DR capabilities for compliance (e.g., DORA, NIS2). ASR provides reporting on failover/failback and integrates with Azure Policy for governance.

Hyper-V Modernization to Azure

Organizations with Hyper-V infrastructure use ASR for lift-and-shift to Azure, later modernizing incrementally from IaaS to PaaS.

Benefits

• Low RPO and configurable RTO for varying workload criticality
• No need to operate your own DR infrastructure
• Regular DR drills without production impact via test failover
• GDPR-compliant operation when choosing EU regions for primary and secondary sites

Frequently Asked Questions about Azure Site Recovery

What is the difference between Azure Backup and Site Recovery?

Azure Backup is for point-in-time recovery of individual files, volumes, or VMs, typically with daily backups and longer retention. Site Recovery is for near-real-time replication of entire VMs with failover orchestration and lower RPO. Backup protects against data loss, while Site Recovery ensures business continuity during site outages. Many organizations use both services together.

How does continuous replication work?

ASR tracks block-level changes on the machines being protected. Changed blocks are compressed, encrypted, and replicated to Azure Storage. ASR creates crash-consistent recovery points at regular intervals and, depending on configuration, application-consistent recovery points. During failover, you select a recovery point and ASR starts VMs from that state.

What happened to the classic experience for VMware/physical servers?

The classic experience for VMware and physical server disaster recovery was retired in March 2026. All workloads must run on the modernized architecture, which uses agent-based replication without a separate configuration server appliance. Newly created Recovery Services vaults exclusively use the modernized architecture.

What workloads are supported?

ASR supports Windows and Linux VMs (Azure VMs, VMware VMs, Hyper-V VMs, physical servers). Supported applications include SQL Server, SharePoint, Exchange, SAP, IIS, and Active Directory. ASR replicates at the block level and is largely application-agnostic, though application-consistent snapshots require VSS support (Windows) or custom scripts (Linux).

What does Azure Site Recovery cost?

ASR is billed per protected instance per month, with pricing differing depending on whether you replicate to Azure or to a customer-owned site. Additional costs apply for replicated storage, storage transactions, data transfer, and compute resources used during an actual failover. Current prices are available on the official Azure pricing page.

How fast is failover?

Failover speed depends on the complexity of the recovery plan: a single VM can typically be recovered within a few minutes, while complex multi-tier applications with many VMs take longer due to sequential boot sequences and post-scripts. Regular test failovers help determine the actual RTO for your environment.

Is Azure Site Recovery GDPR compliant?

Yes, ASR can be operated in compliance with GDPR when EU regions are chosen as primary and secondary sites. Microsoft provides data processing agreements under Art. 28 GDPR as well as encryption of data in transit and at rest. Failover to non-EU regions may violate data residency requirements and should be reviewed in advance.

Integration with innFactory

As a Microsoft Solutions Partner, innFactory supports you in implementing Azure Site Recovery. We help with DR strategy, recovery plan design, migration planning, and DR drill execution.

Contact us for a non-binding consultation on Azure Site Recovery and disaster recovery.