Overview of Azure Site Recovery and Things to know about Azure Site Recovery

Azure Site Recovery (ASR) is a disaster recovery as a service (DRaaS) solution that helps organizations protect their critical workloads by enabling business continuity in the event of planned or unplanned outages.

ASR automates the replication, failover, and recovery of workloads to a secondary location, either within Azure or an on-premises data center.

Key Features of Azure Site Recovery

1. Disaster Recovery for Workloads:

   • Supports replication of Azure VMs, on-premises virtual machines (Hyper-V/VMware), and physical servers.

2. Failover and Failback:

   • Seamless failover to a secondary region or site in case of outages.

   • Failback to the primary site after recovery.

3. Continuous Replication:

   • Ensures minimal data loss with near real-time replication.

   • Tracks changes asynchronously and applies them to the target location.

4. Customizable Recovery Plans:

   • Automates the failover sequence for multi-tier applications.

   • Includes scripts and manual intervention steps if necessary.

5. Cross-Region and Hybrid Support:

   • Enables cross-region disaster recovery within Azure.

   • Supports on-premises to Azure and Azure to Azure disaster recovery.

6. Compliance and Security:

   • Data is encrypted in transit and at rest.

   • Meets regulatory requirements for business continuity.

7. Test Failover:

   • Allows testing of disaster recovery plans without disrupting live workloads.

How Azure Site Recovery Works

1. Replication:

   • Data from the source (Azure VM, on-premises VM, or physical server) is continuously replicated to the target location.

2. Recovery Plan:

   • Users configure a recovery plan to orchestrate failover sequences, dependencies, and scripts.

3. Failover:

   • When a disaster occurs, workloads are failed over to the secondary site or Azure region.

   • Options include planned failover (with no data loss) and unplanned failover (data loss depends on recovery point).

4. Failback:

   • After the primary site is restored, data and workloads are failed back to their original locations.

Things to Know About Azure Site Recovery

Supported Scenarios

1. On-Premises to Azure: Replication of Hyper-V/VMware VMs or physical servers to Azure.

2. Azure to Azure: Replication of Azure VMs from one region to another for regional disaster recovery.

3. Hybrid Scenarios: Useful for hybrid environments where on-premises and Azure workloads coexist.

Prerequisites

1. Replication Agent: On-premises machines require agents (e.g., Azure Site Recovery Mobility Service) for data replication.

2. Network Requirements: Proper bandwidth and VPN/ExpressRoute setup are essential for seamless replication.

3. Azure Components: Requires a Recovery Services Vault to manage replication and recovery processes.

Replication Frequency

1. Near-continuous replication ensures minimal data loss.

2. Replication granularity varies by workload:

   • Azure VMs typically use 30-second replication intervals.

   • On-premises VMs may depend on bandwidth and infrastructure.

Recovery Objectives

1. Recovery Time Objective (RTO): Time taken to restore workloads after an outage.

2. Recovery Point Objective (RPO): Maximum acceptable amount of data loss, determined by replication frequency.

Pricing Considerations

1. Replication Costs: Azure charges for storage used by replicated data in the secondary region.

2. Compute Costs: During failover, compute charges apply for running workloads in the secondary region.

3. ASR Licensing: Site Recovery is billed per protected instance.

Security and Compliance

1. Replicated data is encrypted using AES 256-bit encryption.

2. Supports compliance for GDPR, ISO, HIPAA, and other regulations.

Integration with Other Services

1. Azure Backup: Complements Site Recovery for data protection and retention.

2. Azure Monitor: Provides insights into replication health and failover readiness.

3. Azure Automation: Automates failover and failback processes.

Key Benefits

1. Cost-Effective: Reduces the need for a secondary physical disaster recovery site.

2. Scalable: Scales with your business needs, whether protecting a single VM or an enterprise-scale workload.

3. Ease of Use: Managed entirely through the Azure portal with minimal manual intervention.

4. Global Reach: Supports replication across Azure's global regions.

Best Practices for Azure Site Recovery

1. Test Recovery Plans: Regularly test failover and failback processes to ensure readiness.

2. Monitor Replication Health: Use Azure Monitor and alerts to detect and resolve replication issues.

3. Optimize Costs: Use Reserved Instances in the secondary region to save costs during failover.

4. Design for Resilience: Use cross-region replication for critical workloads.

5. Maintain Updated Documentation: Ensure recovery plans and steps are current and accessible.

Summary

Azure Site Recovery ensures organizations can achieve robust disaster recovery and business continuity with minimal downtime and data loss.

It’s a key part of any enterprise-grade resilience strategy.