Types of Disaster Recovery Plans

Standard Operating Procedure: Taxonomy, Selection, and Execution of Disaster Recovery Plans

1. Document Control Block

• Document ID: SOP-TR-ENG-DR-042
• Effective Date: October 24, 2023
• Version: 3.2.0
• Review Cadence: Semi-Annual (Next Review: April 24, 2024)
• Owner: Julian Vance, Chief Architect, Template Registry
• Classification: Internal / Restricted Operations

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2. Executive Summary & Purpose

This Standard Operating Procedure (SOP) defines the institutional framework, classification taxonomy, and operational lifecycle for Disaster Recovery Plans (DRPs) across all Template Registry production environments. The purpose is to establish a deterministic, repeatable methodology for selecting, maintaining, and executing the appropriate DR tier to guarantee business continuity, data integrity, and strict adherence to defined Recovery Time Objectives (RTO) and Recovery Point Objectives (RPO) during catastrophic system failures.

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3. Scope & Prerequisites

3.1 Scope

This policy applies to all core microservices, data persistence layers, message brokers, edge routing infrastructure, and multi-region deployments managed by Template Registry engineering teams.

3.2 Prerequisites & Required Tooling

• Access Control: Multi-Factor Authentication (MFA) with Hardware Security Keys (FIDO2) and elevated administrative permissions within AWS/GCP and HashiCorp Terraform Cloud.
• Secret Management: HashiCorp Vault access for dynamic operational token generation.
• Observability Suites: Datadog APM, Prometheus/Grafana operational dashboards, and PagerDuty enterprise routing.
• Infrastructure as Code (IaC): Terraform CLI (v1.5+), Ansible core, and Atlantis integration for state management.
• Physical Safety / PPE: Not applicable (pure cloud-native infrastructure architecture).

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4. Roles & Responsibilities

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5. Step-by-Step Procedure

Phase 1: Taxonomy Identification & DRP Selection

• 1.1 Audit the targeted workload against the business impact analysis (BIA) matrix to determine the required classification tier:
  • Tier 1 (Backup & Restore): Non-critical batch processing; RTO: 24h, RPO: 24h.
  • Tier 2 (Pilot Light): Minimal core services provisioned continuously; database replicated asynchronously; RTO: 4h, RPO: 1h.
  • Tier 3 (Warm Standby): Scaled-down production replica running concurrently; RTO: 1h, RPO: 15m.
  • Tier 4 (Multi-Site Active-Active): Instantaneous load distribution across independent geographical regions; RTO: <1m, RPO: ~0.
• 1.2 Document the selected DRP typology in the service catalog metadata repository via automated PR against the infrastructure registry.

Phase 2: Pre-Execution Validation & Failover Preparation

• 2.1 Verify operational health of replication links, storage snapshots, and synchronization logs via Datadog dashboard sys-dr-replication-health.
• 2.2 Convene the Incident Response Bridge and formally assign the Incident Commander (IC) role.
• 2.3 Execute pre-flight verification script to ensure target DR region resource quotas are unconstrained:

  terraform plan -target=module.dr_region_infrastructure -out=dr_activation.tfplan
  

Phase 3: DRP Execution & Infrastructure Activation

• 3.1 Initiate DNS failover routing or global traffic manager (GTM) weight shifting away from the compromised primary region:

  aws route53 change-resource-record-sets --hosted-zone-id Z123456 --change-batch file://failover-dns-routing.json
  

• 3.2 Promote the secondary/replica data persistence layer to primary status, cutting off upstream replication lag:

  pg_ctl promote -D /var/lib/postgresql/data
  

• 3.3 Apply Terraform execution plan to scale up stateless application nodes in the DR target region to full production capacity:

  terraform apply dr_activation.tfplan
  

Phase 4: Post-Failover Validation & Handover

• 4.1 Run automated end-to-end integration and smoke test suites against the newly promoted regional endpoints:

  pytest --environment=dr-failover --maxfail=1
  

• 4.2 Verify application telemetry, latency percentiles (p99), and error rates in Grafana to ensure system stability.
• 4.3 Transfer operational ownership back to the primary engineering teams and broadcast the "All Clear" signal via PagerDuty and status page update.

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6. Quality Assurance & Pro-Tips

Best Practices

• Immutable Backups: Ensure all Tier 1 and Tier 2 backups reside in write-once-read-many (WORM) storage buckets with strict root-account deletion protection.
• Continuous Testing: Perform unannounced, automated DRP failover drills for Tier 3 and Tier 4 systems every quarter using chaos engineering frameworks.

Common Pitfalls

• Split-Brain Syndromes: Forgetting to sever incoming write connections to the legacy primary database prior to promoting the replica, resulting in catastrophic data divergence.
• Hardcoded Endpoints: Relying on hardcoded IP addresses or regional DNS strings within application configuration bundles rather than dynamic service discovery.

Metric Thresholds

• Max Allowable RPO Deviation: $\le 5%$ variance from the tier-specified ceiling.
• Max Allowable RTO Breach: $\le 10%$ overage before mandatory executive escalation.

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7. Frequently Asked Questions

• Q: How do we determine when to initiate a full multi-region failover versus localized service restarting?
  A: Initiate a full DRP execution only when the primary region experiences a localized infrastructure failure exceeding 15 minutes of unmitigated downtime, or when hardware isolation prevents local container orchestration recovery. Localized cluster degradation must be handled via standard pod eviction and rescheduling protocols.

• Q: What is the mandatory protocol if data replication lag exceeds the defined RPO threshold during a failover event?
  A: The Incident Commander must pause the promotion sequence, consult the lead Database Administrator to evaluate point-in-time recovery (PITR) logs, and explicitly brief executive leadership on the extent of potential data loss before executing a forced promotion.