Table of Contents

Disaster Recovery Design

Overview

Comprehensive disaster recovery architecture and procedures for enterprise infrastructure resilience and business continuity.

DR Architecture Components

Multi-Site Design

graph TB
    subgraph "Primary Site"
        PrimaryDC[Primary Data Center]
        PrimaryServers[Production Servers]
        PrimaryStorage[Primary Storage]
        PrimaryNetwork[Primary Network Infrastructure]
        PrimaryUsers[Primary User Base]
    end
    
    subgraph "Secondary Site"
        SecondaryDC[Secondary Data Center]
        SecondaryServers[Standby Servers]
        SecondaryStorage[Replicated Storage]
        SecondaryNetwork[Secondary Network Infrastructure]
        SecondaryUsers[Backup User Access]
    end
    
    subgraph "Cloud DR Site"
        CloudDC[Cloud Data Center]
        CloudVMs[Cloud Virtual Machines]
        CloudStorage[Cloud Storage]
        CloudNetwork[Cloud Network]
        CloudUsers[Cloud User Access]
    end
    
    subgraph "Replication Services"
        DataReplication[Data Replication]
        AppReplication[Application Replication]
        ConfigReplication[Configuration Replication]
    end
    
    PrimaryDC <--> DataReplication
    DataReplication <--> SecondaryDC
    DataReplication <--> CloudDC
    PrimaryServers --> AppReplication
    AppReplication --> SecondaryServers
    AppReplication --> CloudVMs
    PrimaryStorage --> ConfigReplication
    ConfigReplication --> SecondaryStorage
    ConfigReplication --> CloudStorage

Recovery Tiers

graph LR
    subgraph "Tier 1 - Critical"
        T1Apps[Mission Critical Apps]
        T1Data[Critical Databases]
        T1Services[Core Services]
        T1Recovery[RTO: 1 Hour, RPO: 15 Min]
    end
    
    subgraph "Tier 2 - Important"
        T2Apps[Important Applications]
        T2Data[Business Databases]
        T2Services[Supporting Services]
        T2Recovery[RTO: 4 Hours, RPO: 1 Hour]
    end
    
    subgraph "Tier 3 - Standard"
        T3Apps[Standard Applications]
        T3Data[Operational Data]
        T3Services[General Services]
        T3Recovery[RTO: 24 Hours, RPO: 4 Hours]
    end
    
    subgraph "Tier 4 - Low Priority"
        T4Apps[Non-Critical Apps]
        T4Data[Archival Data]
        T4Services[Optional Services]
        T4Recovery[RTO: 72 Hours, RPO: 24 Hours]
    end

Data Protection Strategy

Backup Architecture

graph TB
    subgraph "Data Sources"
        Databases[Database Systems]
        FileServers[File Servers]
        VirtualMachines[Virtual Machines]
        Applications[Application Data]
        Configurations[System Configurations]
    end
    
    subgraph "Backup Infrastructure"
        BackupServers[Backup Servers]
        BackupStorage[Backup Storage]
        DedupAppliances[Deduplication Appliances]
        TapeLibrary[Tape Library]
    end
    
    subgraph "Backup Targets"
        LocalStorage[Local Backup Storage]
        OffSiteStorage[Off-Site Storage]
        CloudBackup[Cloud Backup]
        TapeArchive[Tape Archive]
    end
    
    subgraph "Backup Processes"
        FullBackup[Full Backup]
        IncrementalBackup[Incremental Backup]
        DifferentialBackup[Differential Backup]
        ContinuousBackup[Continuous Backup]
    end
    
    Databases --> BackupServers
    FileServers --> BackupServers
    VirtualMachines --> BackupServers
    Applications --> BackupServers
    BackupServers --> BackupStorage
    BackupStorage --> DedupAppliances
    DedupAppliances --> LocalStorage
    LocalStorage --> OffSiteStorage
    LocalStorage --> CloudBackup
    OffSiteStorage --> TapeArchive

Replication Technologies

Database Replication

sequenceDiagram
    participant Primary as Primary Database
    participant Replica as Secondary Replica
    participant DR as DR Site Database
    participant Monitor as Replication Monitor
    
    Primary->>Replica: Synchronous Replication
    Primary->>DR: Asynchronous Replication
    Primary->>Monitor: Replication Status
    Replica->>Monitor: Health Check
    DR->>Monitor: Replication Lag
    Monitor->>Primary: Performance Metrics
    
    Note over Primary,DR: Continuous Data Protection
    Note over Monitor: Real-time Monitoring

Storage Replication

  • Block-level replication
  • File-level replication
  • Application-consistent snapshots
  • Cross-site storage mirroring

Recovery Procedures

Failover Process

graph TB
    subgraph "Disaster Detection"
        MonitoringSystem[Monitoring System]
        AlertSystem[Alert System]
        AutoDetection[Automatic Detection]
        ManualTrigger[Manual Trigger]
    end
    
    subgraph "Decision Process"
        IncidentAssessment[Incident Assessment]
        DRTeamActivation[DR Team Activation]
        FailoverDecision[Failover Decision]
        StakeholderNotification[Stakeholder Notification]
    end
    
    subgraph "Failover Execution"
        DNSUpdate[DNS Updates]
        NetworkRerouting[Network Rerouting]
        ServiceActivation[Service Activation]
        DataValidation[Data Validation]
        UserNotification[User Notification]
    end
    
    subgraph "Post-Failover"
        SystemMonitoring[System Monitoring]
        PerformanceTuning[Performance Tuning]
        UserSupport[User Support]
        IncidentDocumentation[Incident Documentation]
    end
    
    MonitoringSystem --> IncidentAssessment
    AlertSystem --> IncidentAssessment
    AutoDetection --> DRTeamActivation
    ManualTrigger --> DRTeamActivation
    IncidentAssessment --> FailoverDecision
    FailoverDecision --> DNSUpdate
    DNSUpdate --> NetworkRerouting
    NetworkRerouting --> ServiceActivation
    ServiceActivation --> DataValidation
    DataValidation --> UserNotification
    UserNotification --> SystemMonitoring

Recovery Testing

Testing Schedule

Test Type Frequency Scope Duration
Backup Restore Test Monthly Individual systems 2-4 hours
Application Failover Quarterly Critical applications 4-8 hours
Site Failover Test Bi-annually Full DR site 8-24 hours
Disaster Simulation Annually Complete infrastructure 24-72 hours

Test Procedures

  1. Planning Phase

    • Test scope definition
    • Resource allocation
    • Timeline establishment
    • Risk assessment
  2. Execution Phase

    • Controlled failover
    • System validation
    • Performance testing
    • User acceptance testing
  3. Validation Phase

    • Data integrity checks
    • Functionality verification
    • Performance validation
    • Security assessment
  4. Documentation Phase

    • Test results documentation
    • Issues identification
    • Improvement recommendations
    • Procedure updates

Business Continuity Planning

Recovery Objectives

Recovery Time Objective (RTO)

graph LR
    subgraph "RTO Definitions"
        Critical[Critical Systems: 1 Hour]
        Important[Important Systems: 4 Hours]
        Standard[Standard Systems: 24 Hours]
        NonCritical[Non-Critical: 72 Hours]
    end
    
    subgraph "Impact Analysis"
        Financial[Financial Impact]
        Operational[Operational Impact]
        Reputation[Reputation Impact]
        Compliance[Compliance Impact]
    end
    
    Critical --> Financial
    Important --> Operational
    Standard --> Reputation
    NonCritical --> Compliance

Recovery Point Objective (RPO)

  • Mission Critical: 15 minutes data loss maximum
  • Business Critical: 1 hour data loss maximum
  • Important: 4 hours data loss maximum
  • Standard: 24 hours data loss maximum

Communication Plan

Internal Communication

graph TB
    subgraph "DR Team"
        DRManager[DR Manager]
        TechnicalLead[Technical Lead]
        NetworkAdmin[Network Admin]
        SystemAdmin[System Admin]
        DatabaseAdmin[Database Admin]
    end
    
    subgraph "Management"
        CTO[Chief Technology Officer]
        CEO[Chief Executive Officer]
        Operations[Operations Manager]
        Communications[Communications Director]
    end
    
    subgraph "External Stakeholders"
        Customers[Customers]
        Vendors[Vendors]
        Partners[Partners]
        Regulators[Regulators]
    end
    
    DRManager --> CTO
    TechnicalLead --> Operations
    CTO --> CEO
    CEO --> Communications
    Communications --> Customers
    Communications --> Vendors
    Operations --> Partners
    Operations --> Regulators

Communication Channels

  • Primary: Corporate email and phone systems
  • Secondary: Mobile phones and personal email
  • Emergency: Satellite phones and radio communication
  • Public: Website updates and social media

Technology Implementation

Automation Tools

# DR Automation Framework
class DisasterRecoveryOrchestrator {
    [string]$PrimarySite
    [string]$DRSite
    [hashtable]$Services
    [string]$ReplicationStatus
    
    DisasterRecoveryOrchestrator([string]$Primary, [string]$DR) {
        $this.PrimarySite = $Primary
        $this.DRSite = $DR
        $this.Services = @{}
        $this.ReplicationStatus = "Active"
    }
    
    [void]InitiateFailover([string]$ServiceTier) {
        Write-Host "Initiating failover for $ServiceTier services" -ForegroundColor Yellow
        
        # Stop services at primary site
        $this.StopPrimaryServices($ServiceTier)
        
        # Start services at DR site
        $this.StartDRServices($ServiceTier)
        
        # Update DNS and routing
        $this.UpdateNetworkRouting()
        
        # Validate services
        $this.ValidateServices($ServiceTier)
    }
    
    [void]StopPrimaryServices([string]$Tier) {
        $TierServices = $this.Services[$Tier]
        foreach ($Service in $TierServices) {
            try {
                Stop-Service $Service -Force
                Write-Host "Stopped service: $Service" -ForegroundColor Green
            }
            catch {
                Write-Error "Failed to stop service $Service : $($_.Exception.Message)"
            }
        }
    }
    
    [void]StartDRServices([string]$Tier) {
        $TierServices = $this.Services[$Tier]
        foreach ($Service in $TierServices) {
            try {
                Invoke-Command -ComputerName $this.DRSite -ScriptBlock {
                    Start-Service $using:Service
                }
                Write-Host "Started DR service: $Service" -ForegroundColor Green
            }
            catch {
                Write-Error "Failed to start DR service $Service : $($_.Exception.Message)"
            }
        }
    }
    
    [void]UpdateNetworkRouting() {
        # Update DNS records
        # Modify load balancer configuration
        # Update firewall rules
        Write-Host "Network routing updated to DR site" -ForegroundColor Green
    }
    
    [bool]ValidateServices([string]$Tier) {
        $ValidationResults = @()
        $TierServices = $this.Services[$Tier]
        
        foreach ($Service in $TierServices) {
            $ServiceCheck = $this.TestServiceHealth($Service)
            $ValidationResults += $ServiceCheck
        }
        
        return ($ValidationResults | Where-Object {$_ -eq $false}).Count -eq 0
    }
    
    [bool]TestServiceHealth([string]$Service) {
        # Implement service-specific health checks
        return $true
    }
}

# DR Testing Framework
function Start-DRTest {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory)]
        [ValidateSet("Backup", "Application", "Site", "Full")]
        [string]$TestType,
        
        [Parameter(Mandatory)]
        [string]$TestScope,
        
        [Parameter()]
        [string]$NotificationList = "dr-team@company.com"
    )
    
    $TestStart = Get-Date
    Write-Host "Starting DR Test: $TestType" -ForegroundColor Cyan
    
    try {
        switch ($TestType) {
            "Backup" {
                $Result = Test-BackupRestore -Scope $TestScope
            }
            "Application" {
                $Result = Test-ApplicationFailover -Scope $TestScope
            }
            "Site" {
                $Result = Test-SiteFailover -Scope $TestScope
            }
            "Full" {
                $Result = Test-FullDR -Scope $TestScope
            }
        }
        
        $TestEnd = Get-Date
        $Duration = $TestEnd - $TestStart
        
        $TestReport = @{
            TestType = $TestType
            Scope = $TestScope
            StartTime = $TestStart
            EndTime = $TestEnd
            Duration = $Duration
            Result = $Result
            Issues = $Result.Issues
            Recommendations = $Result.Recommendations
        }
        
        Send-DRTestReport -Report $TestReport -Recipients $NotificationList
    }
    catch {
        Write-Error "DR Test failed: $($_.Exception.Message)"
    }
}

Monitoring and Alerting

  • Replication lag monitoring
  • Backup job status tracking
  • DR site health checks
  • Network connectivity monitoring
  • Performance baseline comparison

Cost Optimization

DR Cost Management

  1. Tiered Recovery Strategy

    • Match recovery requirements to business criticality
    • Use appropriate technology for each tier
    • Regular cost-benefit analysis
  2. Cloud DR Solutions

    • Pay-as-you-go model
    • Reserved capacity for critical systems
    • Automated scaling during disasters
  3. Resource Optimization

    • Right-sizing DR infrastructure
    • Shared DR sites for multiple applications
    • Regular capacity planning reviews

Compliance and Governance

Regulatory Requirements

  • Data residency requirements
  • Recovery time mandates
  • Audit trail maintenance
  • Compliance reporting

Documentation Standards

  • DR procedures documentation
  • Test result records
  • Incident response logs
  • Change management records