Cloud Disaster Recovery Cost Guide: Pilot Light vs Warm Standby vs Active-Active Pricing
DR Strategies and Their Cost Profiles
Cloud disaster recovery can range from nearly free (backup and restore) to 2× your production cost (active-active multi-region). Understanding the cost-RTO trade-off is essential for choosing the right approach.
The Four DR Strategies
| Strategy | RTO | RPO | Cost vs Production |
|---|---|---|---|
| Backup & Restore | Hours-Days | Hours | 5-10% |
| Pilot Light | Minutes-Hours | Minutes | 10-15% |
| Warm Standby | Minutes | Seconds-Minutes | 40-60% |
| Active-Active | Near-Zero | Near-Zero | 100-200% |
Backup and Restore
Lowest cost DR strategy. Back up data to S3/Blob with cross-region replication. In disaster, provision infrastructure from scratch using IaC (Terraform/CloudFormation) and restore data from backup.
- AWS S3 cross-region replication: $0.015/GB + egress
- AWS Backup: $0.05/GB stored + $0.0065/GB restore
- RTO: 2-24 hours depending on infrastructure size and data volume
- Monthly cost for 10TB backup: ~$150-300
Pilot Light
Core infrastructure is pre-provisioned in DR region in minimal state (databases running, app servers off). In disaster, scale up quickly from existing database with new compute.
Cost model: Database (running) + small NAT gateway + minimal networking = 10-15% of production cost. For a $10,000/month production environment: ~$1,000-1,500/month DR cost.
Warm Standby
Reduced-capacity production-like environment running in DR region. Scale up quickly when failover needed.
Example: Production = 20× m7i.xlarge. Warm standby = 4× m7i.xlarge (20% capacity). Cost: ~$590/month for 4 nodes vs $2,956/month for full production.
Active-Active Multi-Region
Full production capacity in both (or more) regions. No failover needed — traffic routes away from failed region automatically.
| Cost Component | Single Region | Active-Active (2 regions) |
|---|---|---|
| Compute | $10,000/mo | $22,400/mo (+12% for second region premium) |
| Database replication | — | $500-2,000/mo |
| Global load balancing | $50/mo | $200-500/mo |
| Cross-region data transfer | — | $200-2,000/mo |
| Total | $10,000 | ~$24,000-27,000 |
Choosing Your DR Strategy
- Non-critical internal tools: Backup & Restore — hours of downtime acceptable
- Business applications (RTO < 4hr): Pilot Light — cost-effective for most internal applications
- Customer-facing applications (RTO < 30min): Warm Standby — balanced cost and recovery speed
- Revenue-critical, regulated applications: Active-Active — no acceptable downtime
AWS vs Azure vs GCP DR Services
- AWS: CloudEndure (now AWS Application Migration Service), DRS, Elastic Disaster Recovery
- Azure: Azure Site Recovery — most comprehensive managed DR service, included in some licence tiers
- GCP: Managed instance group-based DR, less turnkey than AWS/Azure
Match DR investment to business impact of downtime. For a $1M/hour revenue application, spending $50,000/month on active-active DR is obvious. For a $5,000 internal tool, backup-and-restore is sufficient.
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