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This lesson explains Elastic Disaster Recovery (DRS) and how it enables fast, cost-effective recovery of on-premises and cloud-based applications on AWS. You’ll learn what DRS does, how it works, operational and cost considerations, and the key components you must configure to perform a successful failover.

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What is Elastic Disaster Recovery?

Elastic Disaster Recovery is a fully managed AWS service that continuously replicates your source servers—physical, virtual, or cloud—into AWS. It uses cost-efficient storage and minimal compute in a staging area, enabling rapid, point-in-time recovery when you need to fail over to AWS.
  • Continuous, block-level replication of operating systems, applications, and data.
  • AWS acts as the recovery site so you don’t need an always-on, duplicate datacenter.
  • Launch only the compute you need during failover, minimizing ongoing costs.
Elastic Disaster Recovery continuously replicates source servers to AWS for near real-time protection and enables point-in-time recovery. Storage for the staging area is billed continuously, and lightweight replication servers in the staging area may incur ongoing compute costs. Compute for recovery instances is billed when those instances are launched for failover or testing.
A slide titled "Elastic Disaster Recovery (DRS)" showing four colorful panels. The panels list features: fully managed disaster recovery service, use AWS as a recovery site, continual replication state, and easy access with disaster recovery infrastructure.

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Supported failover scenarios

DRS supports multiple source-to-AWS scenarios so you can choose AWS as your recovery target regardless of where your production workloads run.

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How DRS works — step-by-step

  1. Identify source servers
    Select the systems you want to protect (physical, virtual, or cloud) — these are your source servers.
  2. Install the AWS Replication Agent
    Install the AWS Replication Agent on each source server that will be protected. The agent performs continuous, block-level replication to AWS.
  3. Configure the staging area and replication settings
    The staging area is an AWS subnet where lightweight replication servers receive incoming block-level data and store snapshots (EBS and related storage). Configure the staging subnet, IAM permissions, and replication options so source servers can continuously send data to AWS.
  4. Understand the three logical architecture zones
    • Source environment (on-premises or other cloud): where your production workloads run.
    • Staging area (in AWS): the intermediate buffer that receives and stores replicated data and snapshots.
    • Recovery subnet (in AWS): where you launch recovery instances during failover or testing.
  5. Define launch settings (launch template)
    Create launch settings that specify how recovery servers are instantiated during failover: EC2 instance type, AMI options, Region, subnet, security groups, IAM role, and any post-boot scripts or initialization commands.
These pieces together enable continuous replication, quick recovery launches, and controlled failback when your primary site is available again.
A presentation slide titled "How DRS Works" with a chip icon on the left. On the right are four colored horizontal boxes labeled "Specifications/Locations", "Instance/Size", "Region/Subnet", and "Security Groups".

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Key components and responsibilities

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Operational and cost considerations

  • Storage and ongoing compute: The staging area stores snapshots continuously (charged as storage) and runs replication servers that may incur ongoing compute cost. Recovery-instance compute is billed only when instances are launched during failover or testing.
  • Network and IAM: Ensure the replication agent can reach the staging area and that IAM policies allow necessary API calls and snapshot management.
  • Testing: Regularly run failover tests to validate launch settings, networking, DNS changes, and application behavior. Test procedures help verify RTO and RPO goals.
Although recovery-instance compute costs occur only while instances run, the staging area incurs continuous storage costs and may run replication servers with ongoing compute charges. Include these recurring costs in your disaster recovery budget and monitor usage regularly.

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Best practices

  • Automate launch templates and initialization scripts to reduce failover time and manual configuration.
  • Configure IAM roles and security groups with least privilege to limit attack surface.
  • Schedule regular failover drills and restore verification to ensure recovery readiness and accurate RTO/RPO.
  • Monitor staging area storage and replication lag to detect issues early.

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Summary

Elastic Disaster Recovery (DRS) is a fully managed AWS solution that continuously replicates physical, virtual, and cloud-based servers into AWS for rapid, point-in-time recovery. By using a staging area and configurable launch settings, DRS lets you reduce the need for a dedicated DR datacenter while supporting fast failover and controlled failback. Key takeaways:
  • DRS protects source servers with continuous, block-level replication to AWS.
  • The staging area stores replicated data and runs lightweight replication servers.
  • Launch settings (launch template) define how recovery instances are created and configured during failover.
Using these components, you can perform rapid failovers to AWS, test recovery regularly, and minimize both capital and operational disaster recovery costs.

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