Enterprise Disaster Recovery Architecture

Purpose

This document defines a reference disaster recovery (DR) architecture for enterprise environments. It provides patterns for meeting recovery time objective (RTO) and recovery point objective (RPO) requirements using storage replication, virtualization, and network failover mechanisms, beyond simple backup and checklist-driven approaches.

Scope and Applicability

This reference applies to:

• Financial services, federal agencies, and critical infrastructure environments
• Hybrid on-premises and virtualized platforms
• Workloads that require defined RTO/RPO targets and auditable DR capabilities

It is not a runbook. Instead, it describes architectural elements that can be adapted into implementation designs and operational procedures.

Architectural Principles

• Requirements-driven design
  RTO/RPO targets are explicitly defined and drive all technical decisions.

• Tiered protection
  Not all workloads receive the same level of DR capability; tiers are defined by business impact.

• Data integrity over raw availability
  Application-consistent recovery is prioritized over simple data copies.

• Automation first
  Failover and failback rely on orchestration and repeatable workflows, not ad hoc procedures.

• Observability and validation
  DR readiness is continuously validated through logging, monitoring, and scheduled exercises.

Logical Architecture

At a logical level, the DR architecture is composed of the following domains:

1. Production Site
   Primary compute, storage, and network services hosting the live workload.

2. Recovery Site
   Secondary site capable of hosting production workloads during an outage, with sufficient compute, storage, and network capacity.

3. Data Protection Layer
   Storage replication, snapshots, and backup systems providing both point-in-time and continuous data protection.

4. Orchestration Layer
   Tools such as VMware SRM or equivalent orchestration platforms that manage sequencing of failover and failback.

5. Network and Identity Layer
   Connectivity, routing, DNS, and identity services (for example Active Directory) required for applications to function after failover.

6. Validation and Observability Layer
   Monitoring, logging, and test harnesses used to validate DR operations and support regulatory examinations.

Physical and Network Architecture

Site Topology

Typical topologies include:

• Two-site primary / DR design with warm or hot standby capacity
• Multi-site active/active architectures for sub-hour RTO requirements

Both designs require:

• Independent power and cooling domains
• Redundant WAN connectivity between sites
• Sufficient compute and storage at the DR site to support prioritized workloads

Storage Replication

Core storage patterns include:

• Synchronous replication

  • Zero or near-zero RPO
  • Limited by distance and network latency
  • Best suited for high-value, low-latency applications

• Asynchronous replication

  • Non-zero but bounded RPO
  • Tolerates higher latency and longer distances
  • Appropriate for most business-critical but non-mission-critical systems

• Application-aware snapshots

  • Coordination with hypervisors and databases to ensure consistency across multi-tier applications
  • Used for both operational recovery and DR use cases

Virtualization Integration

Virtualization platforms provide key DR capabilities:

• Site Recovery Manager (SRM) or equivalent

  • Automated runbooks and failover plans
  • Reduced human error and consistent sequencing

• vMotion / live migration

  • Facilitates planned migrations between sites when latency and network design allow

• Storage vMotion

  • Enables non-disruptive storage migrations and reprotection activities

Network Architecture

Network design must support addressability, routing, and secure access during DR events:

• Multi-site connectivity

  • BGP route advertisement for dynamic path changes
  • VLAN extensions or overlay networks where L2 adjacency is required
  • Load balancers capable of directing traffic to the active site

• DNS integration

  • DNS changes or global traffic management to direct users to services at the DR site
  • Low TTLs on critical records to accelerate cutover

• Bandwidth planning

  • Dedicated replication links or QoS to protect production traffic
  • Compression and deduplication for replication flows
  • Capacity planning for both steady-state replication and burst conditions during failover

Control and Deployment Patterns

RTO/RPO Tiers

Typical tiers and cost profiles:

• Tier 0 – Sub-hour RTO, near-zero RPO

  • Active/active architectures
  • Highest infrastructure and operational cost

• Tier 1 – 1-hour RTO, low RPO

  • Hot standby with real-time or near-real-time replication
  • Requires pre-provisioned compute at DR site

• Tier 2 – 4-hour RTO, moderate RPO

  • Warm standby with scheduled replication and reserved capacity

• Tier 3 – 24-hour RTO, daily backups

  • Backup-only protection
  • Lowest cost, appropriate for non-critical workloads

Each tier dictates storage replication type, compute reservation at DR, and operational processes.

Application-Specific Patterns

• Databases

  • Use native replication or clustering where available
  • Align database failover sequence with application and middleware layers

• Stateless web tiers

  • Use image/VM templates and configuration management for rapid rebuild
  • Store state in external databases or caches

• File and object storage

  • Use replication and geo-redundant storage where available
  • Define clear conflict resolution policies for multi-site write scenarios

Identity and Directory Services

Identity services must remain available during DR events:

• Domain controllers distributed across sites
• Global Catalog servers present in each major site
• Certificate services replicated and protected
• DNS integrated with the DR failover model

Operational Considerations

DR Testing

Regular DR exercises are required to validate the architecture:

• Complete failover tests

  • Full migration of prioritized workloads to the DR site

• Partial failover tests

  • Focused on critical applications and services

• Unannounced or surprise tests

  • Validate readiness without extended preparation

• Network partition testing

  • Validate behavior during partial connectivity failures

Runbooks and Documentation

Operational documentation includes:

• Step-by-step failover and failback procedures
• Contact lists and escalation paths
• Validation checklists to confirm service restoration
• Rollback procedures for failed DR attempts

Regulatory and Audit Alignment

Design and testing outputs should map to:

• Internal business continuity policies
• Regulatory frameworks relevant to financial, federal, or critical infrastructure sectors
• Evidence expectations for independent audits and examinations

Dependencies and Preconditions

• Available and tested storage replication capabilities
• Adequately sized compute and storage resources at DR sites
• Reliable and secured WAN connectivity
• Up-to-date CMDB and application topology documentation
• Identity and DNS services designed to operate from multiple sites

Risks and Limitations

• Latency constraints
  Synchronous replication and real-time failover are limited by physical distance and network performance.

• Cost escalation
  Aggressive RTO/RPO targets significantly increase infrastructure and licensing costs.

• Configuration drift
  Inconsistent configuration between production and DR environments can cause failover failures.

• Operational gaps
  Infrequent or poorly designed testing leads to unvalidated assumptions.

• Over-reliance on a single technology
  DR must consider storage, compute, network, and identity collectively, not as isolated components.

Related Entries

• Open Systems Reference Platform - Platform hosting implementation examples
• Palo Alto PA-220 Reference - Network failover considerations
• Authentik OIDC for Proxmox - Identity service integration patterns

Implementation Notes

This reference architecture has been validated across financial services and federal environments. Implementation should begin with clear RTO/RPO requirements definition, followed by infrastructure capacity planning and detailed runbook development.

Future revisions will add platform-specific implementation guides as separate repository entries linked to this foundational pattern.