What are Disaster Recovery and Business Continuity?

Question

Accepted Answer

**DR (Disaster Recovery)** — recovery after disaster. **BC (Business Continuity)** — business continuity.

**Metrics:**
- **RPO (Recovery Point Objective)** — maximum data loss (hours).
- **RTO (Recovery Time Objective)** — maximum downtime (hours).

**DR Strategies:**

**1. Backup & Restore (RPO=24h, RTO=4h):**
```bash
velero schedule create daily-backup --schedule="@daily"
pg_dump -U postgres mydb | aws s3 cp - s3://backups/db.sql
```

**2. Pilot Light (RPO=1h, RTO=30min):** Minimal standby (only DB + DNS).

**3. Warm Standby (RPO=15min, RTO=10min):** Reduced copy of production.

**4. Multi-Site Active-Active (RPO≈0, RTO≈0):** Full copies in two regions.

**Kubernetes DR (Velero):**
```bash
# Backup
velero backup create prod-backup-$(date +%Y%m%d) --include-namespaces production

# Restore to another cluster
velero restore create --from-backup prod-backup-20240115 \
  --namespace-mappings production:dr-production
```

**Multi-Region DNS failover:**
```hcl
resource "aws_route53_health_check" "primary" {
  fqdn = "primary.myapp.com"
  port = 443
  type = "HTTPS"
  failure_threshold = 3
  request_interval = 10
}

resource "aws_route53_record" "failover" {
  zone_id = aws_route53_zone.main.zone_id
  name    = "myapp.com"
  type    = "A"
  failover_routing_policy {
    type = "FAILOVER"
  }
  set_identifier  = "primary"
  health_check_id = aws_route53_health_check.primary.id
  alias {
    name    = aws_lb.primary.dns_name
    zone_id = aws_lb.primary.zone_id
  }
}
```

**Testing:** Regular DR drills (once per quarter).

DevOps: What are Disaster Recovery and Business Continuity?