High Availability & Disaster Recovery

Naas is architected for enterprise-grade availability and resilience, with comprehensive disaster recovery capabilities that ensure business continuity even in the face of major infrastructure failures. Our multi-layered approach to availability provides 99.9%+ uptime guarantees with rapid recovery capabilities.

Professional Services Implementation

The enterprise capabilities described in this section represent our ability to implement these solutions through our professional services team. Each deployment is customized to your specific requirements and implemented with dedicated support. Contact our enterprise team at [email protected] to discuss your needs and implementation timeline.

High Availability Architecture

Multi-Zone Deployment

Availability Zone Strategy:

• Primary Zone: Main operational zone with full capacity
• Secondary Zones: Hot standby zones with automatic failover
• Cross-Zone Replication: Real-time data replication across zones
• Load Distribution: Intelligent traffic distribution across zones

Zone Failure Scenarios:

Automatic Failover Configuration:

# High availability configuration
high_availability:
  zones:
    primary: "us-east-1a"
    secondary: ["us-east-1b", "us-east-1c"]
  
  failover:
    detection_timeout: "30 seconds"
    failover_time: "2 minutes"
    automatic: true
    health_checks:
      - endpoint: "/health"
        interval: "10 seconds"
        timeout: "5 seconds"
        retries: 3
  
  load_balancing:
    algorithm: "least_connections"
    sticky_sessions: false
    health_check_grace_period: "60 seconds"

Database High Availability

PostgreSQL High Availability:

• Streaming Replication: Synchronous replication for zero data loss
• Connection Pooling: PgBouncer for connection management
• Automatic Failover: Patroni for automated failover management
• Point-in-Time Recovery: Continuous WAL archiving

Database Cluster Configuration:

# PostgreSQL HA configuration
postgresql_ha:
  cluster_name: "naas-postgres"
  
  nodes:
    primary:
      name: "postgres-primary"
      zone: "us-east-1a"
      instance_type: "db.r5.2xlarge"
    
    replicas:
      - name: "postgres-replica-1"
        zone: "us-east-1b"
        instance_type: "db.r5.2xlarge"
        replication: "synchronous"
      
      - name: "postgres-replica-2"
        zone: "us-east-1c"
        instance_type: "db.r5.2xlarge"
        replication: "asynchronous"
  
  failover:
    automatic: true
    timeout: "30 seconds"
    promotion_timeout: "60 seconds"

Redis High Availability:

• Redis Sentinel: Automatic failover for Redis instances
• Cluster Mode: Distributed Redis cluster for scalability
• Persistence: RDB and AOF persistence for data durability
• Memory Management: Automatic memory optimization and eviction

Service Mesh Resilience

Istio Service Mesh:

• Circuit Breakers: Automatic failure detection and isolation
• Retry Policies: Configurable retry logic with exponential backoff
• Timeout Management: Request timeout configuration
• Traffic Splitting: Gradual traffic migration during deployments

Circuit Breaker Configuration:

# Istio circuit breaker configuration
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: naas-api-circuit-breaker
spec:
  host: naas-api-service
  trafficPolicy:
    outlierDetection:
      consecutiveErrors: 3
      interval: 30s
      baseEjectionTime: 30s
      maxEjectionPercent: 50
    connectionPool:
      tcp:
        maxConnections: 100
      http:
        http1MaxPendingRequests: 50
        maxRequestsPerConnection: 10

Retry and Timeout Policies:

# Retry and timeout configuration
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: naas-api-retry-policy
spec:
  http:
  - retries:
      attempts: 3
      perTryTimeout: 10s
      retryOn: "5xx,reset,connect-failure,refused-stream"
    timeout: 30s

Application-Level Resilience

Graceful Degradation:

• Feature Flags: Dynamic feature enabling/disabling
• Fallback Mechanisms: Alternative processing paths during failures
• Cache Strategies: Multi-level caching for improved resilience
• Asynchronous Processing: Queue-based processing for non-critical operations

Health Check Implementation:

# Application health check example
from fastapi import FastAPI, HTTPException
from typing import Dict, Any
import asyncio
import time

app = FastAPI()

class HealthChecker:
    def __init__(self):
        self.checks = {
            "database": self.check_database,
            "redis": self.check_redis,
            "external_api": self.check_external_api
        }
    
    async def check_database(self) -> Dict[str, Any]:
        try:
            # Database connectivity check
            result = await db.execute("SELECT 1")
            return {
                "status": "healthy",
                "response_time": 0.05,
                "details": "Database connection successful"
            }
        except Exception as e:
            return {
                "status": "unhealthy",
                "error": str(e),
                "details": "Database connection failed"
            }
    
    async def check_redis(self) -> Dict[str, Any]:
        try:
            # Redis connectivity check
            await redis.ping()
            return {
                "status": "healthy",
                "response_time": 0.02,
                "details": "Redis connection successful"
            }
        except Exception as e:
            return {
                "status": "unhealthy",
                "error": str(e),
                "details": "Redis connection failed"
            }

@app.get("/health")
async def health_check():
    checker = HealthChecker()
    results = {}
    overall_status = "healthy"
    
    for check_name, check_func in checker.checks.items():
        result = await check_func()
        results[check_name] = result
        if result["status"] != "healthy":
            overall_status = "unhealthy"
    
    return {
        "status": overall_status,
        "timestamp": time.time(),
        "checks": results
    }

Disaster Recovery

Recovery Time and Point Objectives

Service Level Objectives:

• RTO (Recovery Time Objective): Maximum acceptable downtime
• RPO (Recovery Point Objective): Maximum acceptable data loss
• MTTR (Mean Time to Recovery): Average time to restore service
• MTBF (Mean Time Between Failures): Average time between failures

SLA Tiers:

# Disaster recovery SLA tiers
sla_tiers:
  standard:
    rto: "4 hours"
    rpo: "1 hour"
    availability: "99.9%"
    support: "business hours"
  
  premium:
    rto: "1 hour"
    rpo: "15 minutes"
    availability: "99.95%"
    support: "24/7"
  
  enterprise:
    rto: "30 minutes"
    rpo: "5 minutes"
    availability: "99.99%"
    support: "24/7 with dedicated TAM"

Backup Strategies

Comprehensive Backup Coverage:

• Database Backups: Continuous WAL archiving with point-in-time recovery
• File System Backups: Incremental backups of application data
• Configuration Backups: Version-controlled infrastructure and application configuration
• Secrets Backup: Encrypted backup of secrets and certificates

Backup Schedule and Retention:

# Backup configuration
backup_strategy:
  database:
    full_backup:
      schedule: "daily at 2:00 AM UTC"
      retention: "30 days"
    
    incremental_backup:
      schedule: "every 4 hours"
      retention: "7 days"
    
    wal_archiving:
      enabled: true
      retention: "7 days"
  
  filesystem:
    schedule: "daily at 3:00 AM UTC"
    retention: "14 days"
    compression: true
    encryption: true
  
  configuration:
    schedule: "on every change"
    retention: "90 days"
    versioning: true

Cross-Region Backup Replication:

• Primary Region: us-east-1 (production and primary backups)
• Secondary Region: us-west-2 (backup replication and DR site)
• Tertiary Region: eu-west-1 (long-term archive storage)

Disaster Recovery Sites

Hot Standby Site:

• Real-time Replication: Continuous data replication to DR site
• Warm Infrastructure: Pre-provisioned infrastructure ready for activation
• Automated Failover: Automatic failover with minimal manual intervention
• Regular Testing: Monthly DR testing and validation

DR Site Architecture:

Cold Standby Site:

• Backup Restoration: Recovery from backups stored in secondary region
• Infrastructure Provisioning: Automated infrastructure provisioning during DR
• Extended Recovery Time: Longer recovery time but lower cost
• Quarterly Testing: Quarterly DR testing and validation

Disaster Recovery Procedures

Disaster Declaration Process:

1. Incident Detection: Automated monitoring or manual reporting
2. Impact Assessment: Evaluate scope and severity of the incident
3. Disaster Declaration: Formal declaration by incident commander
4. DR Team Activation: Activate disaster recovery team and procedures
5. Stakeholder Notification: Notify customers, partners, and regulators

Recovery Procedures:

# Disaster recovery runbook
disaster_recovery:
  detection:
    - automated_monitoring: "System health checks fail"
    - manual_trigger: "Operations team declares disaster"
    - external_notification: "Cloud provider outage notification"
  
  assessment:
    - scope_evaluation: "Determine affected systems and users"
    - impact_analysis: "Assess business impact and urgency"
    - recovery_strategy: "Select appropriate recovery approach"
  
  execution:
    - infrastructure_activation: "Provision DR infrastructure"
    - data_restoration: "Restore data from backups or replicas"
    - service_validation: "Validate service functionality"
    - traffic_redirection: "Redirect user traffic to DR site"
  
  communication:
    - internal_notification: "Notify internal stakeholders"
    - customer_communication: "Update status page and notify customers"
    - regulatory_reporting: "File required regulatory reports"

Recovery Validation:

• Smoke Tests: Basic functionality verification
• Integration Tests: End-to-end workflow validation
• Performance Tests: System performance validation
• Security Tests: Security control validation

Business Continuity

Continuity Planning

Business Impact Analysis:

• Critical Processes: Identification of mission-critical business processes
• Dependencies: Mapping of system and process dependencies
• Recovery Priorities: Prioritization of recovery activities
• Resource Requirements: Identification of required resources for recovery

Continuity Strategies:

# Business continuity strategies
continuity_strategies:
  prevention:
    - redundant_systems: "Multiple availability zones"
    - proactive_monitoring: "24/7 system monitoring"
    - preventive_maintenance: "Regular system maintenance"
  
  mitigation:
    - graceful_degradation: "Reduced functionality during incidents"
    - load_shedding: "Prioritize critical operations"
    - alternative_workflows: "Manual processes when systems unavailable"
  
  recovery:
    - automated_failover: "Automatic system recovery"
    - manual_procedures: "Documented manual recovery steps"
    - communication_plans: "Stakeholder communication procedures"

Crisis Communication

Communication Channels:

• Status Page: Public status page for service availability
• Email Notifications: Automated email alerts to subscribers
• SMS Alerts: Critical alerts via SMS for urgent issues
• Social Media: Updates via Twitter and LinkedIn
• Direct Communication: Phone calls for major customers

Communication Templates:

# Crisis communication templates
communication_templates:
  incident_notification:
    subject: "Service Disruption - [Service Name]"
    template: |
      We are currently experiencing an issue with [service_name] that began at [start_time].
      
      Impact: [impact_description]
      Current Status: [current_status]
      Next Update: [next_update_time]
      
      We apologize for any inconvenience and are working to resolve this as quickly as possible.
  
  resolution_notification:
    subject: "Service Restored - [Service Name]"
    template: |
      The issue with [service_name] has been resolved as of [resolution_time].
      
      Root Cause: [root_cause_summary]
      Resolution: [resolution_summary]
      
      We will conduct a post-incident review and share findings within 48 hours.

Testing and Validation

DR Testing Schedule:

• Monthly: Backup restoration testing
• Quarterly: Partial DR site activation
• Semi-annually: Full DR site failover test
• Annually: Comprehensive business continuity exercise

Testing Procedures:

# DR testing procedures
dr_testing:
  backup_restoration:
    frequency: "monthly"
    scope: "database and critical data"
    validation: "data integrity and completeness"
    rollback: "automatic rollback after testing"
  
  failover_testing:
    frequency: "quarterly"
    scope: "application services failover"
    validation: "end-to-end functionality"
    duration: "4 hours maximum"
  
  full_dr_exercise:
    frequency: "annually"
    scope: "complete system failover"
    validation: "business process continuity"
    stakeholders: "all business units"

Test Results Documentation:

• Test Execution Logs: Detailed logs of all test activities
• Performance Metrics: Recovery time and data loss measurements
• Issue Identification: Documentation of any issues discovered
• Improvement Recommendations: Recommendations for process improvements

Monitoring and Alerting

Comprehensive Monitoring

Infrastructure Monitoring:

• Server Metrics: CPU, memory, disk, network utilization
• Container Metrics: Pod resource usage and health status
• Network Metrics: Bandwidth utilization and latency
• Storage Metrics: Disk usage, IOPS, and throughput

Application Monitoring:

• Response Times: API and web interface response times
• Error Rates: Application error rates and types
• Throughput: Request volume and processing rates
• User Experience: Real user monitoring and synthetic testing

Monitoring Stack:

# Monitoring configuration
monitoring:
  metrics:
    prometheus:
      retention: "30 days"
      scrape_interval: "15 seconds"
      alerting_rules: "custom_rules.yml"
    
    grafana:
      dashboards: "infrastructure, application, business"
      alerting: "integrated with PagerDuty"
  
  logging:
    elasticsearch:
      retention: "90 days"
      indices: "daily rotation"
      replicas: 2
    
    kibana:
      dashboards: "security, application, audit"
      access_control: "role-based"
  
  tracing:
    jaeger:
      sampling_rate: "0.1%"
      retention: "7 days"
      storage: "elasticsearch"

Intelligent Alerting

Alert Categories:

• Critical: Immediate response required (page on-call engineer)
• Warning: Issue requires attention within business hours
• Info: Informational alerts for trend analysis

Alert Escalation:

# Alert escalation configuration
alerting:
  escalation_policies:
    critical:
      - level_1: "on_call_engineer"
        timeout: "5 minutes"
      - level_2: "engineering_manager"
        timeout: "15 minutes"
      - level_3: "cto"
        timeout: "30 minutes"
    
    warning:
      - level_1: "engineering_team_slack"
        timeout: "30 minutes"
      - level_2: "engineering_manager"
        timeout: "2 hours"
  
  notification_channels:
    - pagerduty: "critical alerts"
    - slack: "warning and info alerts"
    - email: "daily summary reports"

For detailed high availability implementation guidance, contact our infrastructure team at [email protected].