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AWS Elastic Disaster Recovery (DRS)

1. Introduction​

AWS Elastic Disaster Recovery (AWS DRS) is a cloud-based disaster recovery service designed to minimize downtime and data loss by continuously replicating on-premises or cloud-based servers into AWS. Built on CloudEndure technology, AWS DRS modernizes disaster recovery by eliminating the need for a permanently idle secondary site, instead leveraging the scalability and cost efficiency of AWS’s global infrastructure. This means you pay only for what you use during replication, drills, or an actual recovery event.

2. What is RPO and RTO?​

Recovery Time Objective (RTO) is the maximum acceptable time period that a system or application can be unavailable after an outage before business operations are significantly impacted. In other words, it defines how quickly you must recover your IT services after a disaster occurs.

Recovery Point Objective (RPO) is the maximum acceptable amount of data loss measured in time. It indicates the age of the files or data that must be recovered from backup storage to resume normal operations. For example, an RPO of five minutes means that in the event of a disaster, you could lose up to five minutes’ worth of data.

Both metrics are critical in disaster recovery planning:

  • RTO focuses on the time it takes to restore functionality.
  • RPO focuses on how much data loss is tolerable.

3. How It Works​

  • Continuous Data Replication:
    AWS DRS installs a lightweight replication agent on your source servers (whether physical, virtual, or cloud-hosted) that continuously replicates data to a designated staging area within your AWS account. The data is encrypted in transit (using TLS 1.2) and stored in cost-effective Amazon EBS volumes.

  • Staging Area & Conversion:
    The staging area uses minimal compute resources while maintaining an up-to-date copy of your servers. When a disaster occurs or you perform a drill, AWS DRS automatically converts your replicated servers to run natively on AWS by adjusting the boot volumes, drivers, and network settings.

  • Failover and Failback:
    In an outage, you can launch recovery instances on AWS in minutes, achieving recovery point objectives (RPOs) in seconds and recovery time objectives (RTOs) in minutes. Once your primary site is restored, you have the option to either fail back to your on-premises environment or continue running your applications in AWS.

4. Key Features​

  • Unified Recovery Process:
    AWS DRS provides a single, streamlined process to test, recover, and fail back your applications without the need for specialized expertise.

  • Non-Disruptive Drills:
    You can perform regular disaster recovery drills without disrupting your production environment. This ensures your recovery plans are always up to date and tested.

  • Automated Launch Management and Post-Launch Actions:
    The service allows you to define default launch settings for recovery instances, and you can also automate post-launch actions—such as configuring monitoring agents or performing health checks—via AWS Systems Manager.

  • Flexible Recovery Options:
    AWS DRS supports recovery to new or existing instances, including the option to convert your source servers so that they run natively on AWS.

  • Automated Network Replication:
    It replicates not only server data but also AWS network components (like VPC configurations), ensuring that your recovery environment mirrors your production setup.

5. Use Cases​

  • On-Premises to AWS:
    Quickly recover operations after unexpected events such as software issues or datacenter hardware failures. AWS DRS enables RPOs of seconds and RTOs of minutes.

    Real World Example: Before 2020, Thomson Reuters’ business unit ONESOURCE Global Trade Management relied on a manual, tape‐based disaster recovery process across two on‑premises data centers. In the fall of 2020, in partnership with Capgemini, they turned to AWS DRS to automate and streamline recovery for 300 servers. In less than 10 months, the new solution enabled continuous replication of over 120 TB of data into a low‑cost staging area on AWS. As a result, the business unit drastically reduced both its recovery time objective (RTO) and recovery point objective (RPO), bolstered security and compliance, and eliminated the need for duplicate on‑premises resources.

  • Cloud-to-AWS:
    Help increase resilience and meet compliance requirements using AWS as your recovery site. AWS DRS converts your cloud-based applications to run natively on AWS.

    Real World Example: Tyler Technologies, which serves local, state, and federal government entities, faced growing challenges with an on‑premises DR solution that could no longer keep pace with its rapidly expanding environment. With over 4,300 virtual machines to protect, the company turned to AWS DRS. By adopting the pay‑as‑you‑go cloud model, Tyler achieved recovery time objectives 12× faster than its legacy solution—restoring mission‑critical workloads in approximately 20 minutes, well within its strict SLA requirements. This transformation not only improved operational resiliency but also converted large capital expenses into predictable operating costs.

  • Cross-Region Recovery within AWS:
    Increase application resilience and help meet availability goals for your AWS-based applications, using AWS DRS to recover applications in a different AWS Region.

6. Pricing​

AWS DRS features a simple, usage-based pricing model. Key pricing components include:

  • Replication Cost:
    You are charged on an hourly basis per source server being replicated (for example, approximately $0.028 per server per hour).

  • Additional AWS Resources:

    • EBS Volumes & Snapshots: Costs vary based on the storage type (e.g., gp3, sc1) and the retention period for snapshots.
    • EC2 Instances: When a drill or failover is initiated, additional charges apply for the replication servers and any launched recovery instances.

7. Considerations​

  • Bandwidth Requirements:
    Continuous replication can consume significant network bandwidth, so it’s essential to ensure that your connectivity is sufficient or consider using private connectivity options (such as AWS Direct Connect or VPN).

  • Failback Process:
    Some users have noted that the failback process could be more intuitive. Testing and regular drills can help identify and mitigate potential issues.

  • Logging and Monitoring:
    While AWS DRS integrates with CloudWatch and CloudTrail, enhanced logging may be required in complex environments to simplify troubleshooting without relying on vendor support.

  • Right-Sizing Resources:
    Optimizing instance types and storage configurations is key to controlling costs during both replication and recovery events.

8. Security and Compliance​

  • Data Encryption:
    All replicated data is encrypted in transit using TLS 1.2 and can be encrypted at rest on AWS using EBS encryption.

  • Private Connectivity:
    AWS DRS supports replication over private connectivity options such as Direct Connect, VPN, or VPC peering, ensuring that data does not traverse the public internet if not desired.

  • Compliance Tools:
    Leveraging AWS’s built-in security, monitoring, and compliance services helps meet regulatory requirements and protect your data throughout the disaster recovery process.

9. Conclusion​

AWS Elastic Disaster Recovery (AWS DRS) is a comprehensive disaster recovery solution that offers fast, reliable, and cost-effective recovery for a wide range of applications. By continuously replicating data to a staging area in AWS, it ensures that your IT systems can be restored quickly during outages—whether due to hardware failures, natural disasters, or even ransomware attacks. Its unified process for testing, recovery, and failback, combined with scalable pricing and robust security measures, makes it an attractive option for businesses looking to enhance their resilience and maintain continuity.

Whether you’re migrating from on-premises environments, safeguarding cloud workloads, or ensuring cross-region resilience, AWS DRS provides the tools and flexibility necessary to protect critical systems with minimal downtime and data loss.