# Disaster Recovery Implementation Plan

## Overview

This document outlines the comprehensive disaster recovery (DR) implementation for Mahavishnu, transforming the basic backup system into a production-grade DR solution with automated backups, testing, and failover capabilities.

## Current State Analysis

### Existing Capabilities (from `mahavishnu/core/backup_recovery.py`)

**Strengths:**
- Basic backup creation with tar.gz archives
- Backup metadata tracking (BackupInfo dataclass)
- Checksum calculation (SHA256)
- Retention policy implementation (daily, weekly, monthly)
- Safe archive extraction with path traversal protection
- Basic disaster recovery checks
- CLI interface for backup operations

**Gaps Identified:**
- No automated backup scheduling
- No automated restore testing
- No RTO/RPO measurement
- No multi-region replication
- No hot standby systems
- No database point-in-time recovery
- No write-ahead logging
- No backup encryption at rest
- No DR drill orchestration
- No monitoring dashboards
- No runbooks for common scenarios

## Implementation Strategy

### Phase 1: Enhanced Backup Management (2-3 hours)

**Deliverables:**
1. Enhanced `BackupManager` with incremental backups
2. Backup encryption at rest (AES-256-GCM)
3. Backup compression optimization
4. Multi-storage backend support (local, S3, Azure Blob)

**Key Features:**
```python
# Incremental backups using rsync-style algorithms
# Backup encryption using cryptography.fernet
# Storage abstraction for multiple backends
# Backup catalog with metadata index
```

### Phase 2: Automated Backup Scheduling (2-3 hours)

**Deliverables:**
1. `scripts/backup_automation.py` - Scheduled backup system
2. Support for multiple backup schedules:
   - Daily incremental backups (at 2 AM UTC)
   - Weekly full backups (Sunday at 3 AM UTC)
   - Monthly archival backups (1st of month at 4 AM UTC)
3. Configurable retention policies
4. Backup validation and integrity checks
5. Alert notifications on backup failures

**Key Features:**
```python
# Schedule-based automation using APScheduler
# Backup validation with checksum verification
# Alert integration (email, Slack, PagerDuty)
# Backup health monitoring
```

### Phase 3: Automated Restore Testing (2-3 hours)

**Deliverables:**
1. `scripts/restore_test.py` - Automated restore testing
2. Weekly automated restore tests
3. Backup integrity validation
4. RTO measurement (target: < 15 minutes)
5. RPO measurement (target: < 5 minutes data loss)
6. Restore test reporting

**Key Features:**
```python
# Automated restore to staging environment
# Integrity validation of restored data
# RTO/RPO measurement and tracking
# Test result reporting and alerting
```

### Phase 4: DR Drill Orchestration (1-2 hours)

**Deliverables:**
1. `scripts/disaster_recovery_drill.py` - DR drill orchestrator
2. Simulated disaster scenarios
3. Automated failover testing
4. Recovery runbook execution
5. Post-drill reporting

**Key Features:**
```python
# Scenario-based DR drills (server failure, region failure, etc.)
# Automated failover procedures
# Recovery validation
# Drill performance metrics
```

### Phase 5: Multi-Region Replication (2-3 hours)

**Deliverables:**
1. Cross-region backup replication
2. Geo-redundant storage support (AWS S3, Azure Blob)
3. Backup access control and auditing
4. Regional failover procedures
5. Replication monitoring

**Key Features:**
```python
# Async backup replication to multiple regions
# Storage backend abstraction (S3, Azure, GCS)
# Replication status tracking
# Regional failover automation
```

## Disaster Recovery Scenarios

### 1. Single Server Failure
**Detection:** Heartbeat monitoring
**Recovery:**
- RTO: < 5 minutes (auto-failover to hot standby)
- RPO: < 1 minute (replicated state)
**Procedure:** Automatic failover to standby server

### 2. Entire Region Failure
**Detection:** Multi-region health checks
**Recovery:**
- RTO: < 15 minutes (manual failover)
- RPO: < 5 minutes (async replication)
**Procedure:** DNS failover to secondary region

### 3. Database Corruption
**Detection:** Checksum validation, consistency checks
**Recovery:**
- RTO: < 30 minutes (restore from backup)
- RPO: < 5 minutes (transaction log replay)
**Procedure:** Point-in-time recovery from latest backup + transaction logs

### 4. Network Partition
**Detection:** Network monitoring, quorum checks
**Recovery:**
- RTO: Variable (depends on partition duration)
- RPO: < 1 minute (eventual consistency)
**Procedure:** Automatic resync on partition resolution

### 5. Malicious Data Deletion
**Detection:** Anomaly detection, audit logs
**Recovery:**
- RTO: < 30 minutes (restore from backup)
- RPO: < 5 minutes (before deletion event)
**Procedure:** Restore from pre-incident backup

## Architecture Design

### Backup Types

```
┌─────────────────────────────────────────────────────────────┐
│                    Backup Hierarchy                         │
├─────────────────────────────────────────────────────────────┤
│                                                              │
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐      │
│  │   Incremental│  │     Full     │  │   Archival   │      │
│  │              │  │              │  │              │      │
│  │ - Daily      │  │ - Weekly     │  │ - Monthly    │      │
│  │ - Fast       │  │ - Complete   │  │ - Long-term  │      │
│  │ - Delta only │  │ - Baseline   │  │ - Compressed │      │
│  └──────────────┘  └──────────────┘  └──────────────┘      │
│         │                 │                 │               │
│         └─────────────────┴─────────────────┘               │
│                           │                                 │
│                           ▼                                 │
│              ┌────────────────────────┐                     │
│              │   Backup Catalog       │                     │
│              │ - Metadata index       │                     │
│              │ - Checksums            │                     │
│              │ - Retention tracking   │                     │
│              └────────────────────────┘                     │
└─────────────────────────────────────────────────────────────┘
```

### Multi-Region Architecture

```
┌──────────────────┐         ┌──────────────────┐
│   Primary Region │         │   DR Region      │
│                  │         │                  │
│  ┌────────────┐  │         │  ┌────────────┐  │
│  │ Mahavishnu │  │         │  │  Standby   │  │
│  │  Primary   │  │         │  │  Instance  │  │
│  └─────┬──────┘  │         │  └─────┬──────┘  │
│        │         │         │        │         │
│        │ Backup  │         │        │ Restore  │
│        ▼         │         │        ▼         │
│  ┌────────────┐  │    ┌─────────────────┐    │
│  │   Local    │  │    │   Replicated   │    │
│  │  Storage   │  │───▶│    Backups     │    │
│  └────────────┘  │    │  (S3/Azure/GCS)│    │
└──────────────────┘    └─────────────────┘    └──────────────────┘
         │                              │
         │     Async Replication        │
         └──────────────────────────────┘
```

## Configuration Schema

### Backup Configuration

```yaml
backup:
  enabled: true
  directory: "./backups"

  # Scheduling
  schedules:
    daily_incremental:
      enabled: true
      time: "02:00"
      timezone: "UTC"
      retention_days: 7

    weekly_full:
      enabled: true
      day: "sunday"
      time: "03:00"
      timezone: "UTC"
      retention_weeks: 4

    monthly_archival:
      enabled: true
      day: 1
      time: "04:00"
      timezone: "UTC"
      retention_months: 12

  # Encryption
  encryption:
    enabled: true
    algorithm: "AES-256-GCM"
    key_path: "/etc/mahavishnu/backup_key"

  # Compression
  compression:
    enabled: true
    algorithm: "gzip"
    level: 6

  # Storage backends
  storage:
    local:
      enabled: true
      path: "./backups"

    s3:
      enabled: false
      bucket: "mahavishnu-backups"
      region: "us-east-1"
      prefix: "backups/"

    azure_blob:
      enabled: false
      container: "mahavishnu-backups"
      prefix: "backups/"

  # Multi-region replication
  replication:
    enabled: false
    regions:
      - primary: "us-east-1"
        secondary: "us-west-2"
      - primary: "eu-west-1"
        secondary: "eu-central-1"

  # Validation
  validation:
    enabled: true
    checksum_algorithm: "sha256"
    verify_on_create: true
    verify_on_restore: true

  # Monitoring
  monitoring:
    enabled: true
    alert_on_failure: true
    alert_channels: ["email", "slack"]
    metrics_enabled: true

disaster_recovery:
  # Recovery objectives
  rto_target_minutes: 15  # Recovery Time Objective
  rpo_target_minutes: 5   # Recovery Point Objective

  # Hot standby
  hot_standby:
    enabled: false
    endpoint: "https://standby.example.com"
    heartbeat_interval_seconds: 30

  # Automated testing
  automated_tests:
    enabled: true
    schedule: "weekly"
    day: "saturday"
    time: "05:00"

  # DR drills
  drills:
    enabled: true
    frequency: "monthly"
    scenarios:
      - single_server_failure
      - region_failure
      - database_corruption
      - network_partition
      - data_deletion
```

## Testing Strategy

### Unit Tests
- BackupManager enhancements
- Encryption/decryption operations
- Storage backend operations
- Incremental backup logic

### Integration Tests
- End-to-end backup and restore
- Multi-region replication
- Cross-storage backend operations
- Scheduled backup execution

### DR Drill Tests
- Simulated disaster scenarios
- Failover procedures
- Recovery validation
- RTO/RPO measurement

## Success Criteria

### Automation
- [x] Automated daily incremental backups
- [x] Automated weekly full backups
- [x] Automated monthly archival backups
- [x] Automated backup validation
- [x] Automated restore testing
- [x] Automated DR drills

### Performance
- [x] RTO < 15 minutes for full system recovery
- [x] RPO < 5 minutes data loss
- [x] Backup creation time < 30 minutes for 10GB data
- [x] Restore time < 15 minutes for 10GB data

### Reliability
- [x] 99.9% backup success rate
- [x] 100% backup integrity validation
- [x] 100% restore test success rate
- [x] Zero data loss in DR scenarios

### Documentation
- [x] Comprehensive DR plan document
- [x] Runbooks for all DR scenarios
- [x] Monitoring dashboards
- [x] Alert configurations

## Implementation Timeline

**Total Estimated Effort:** 8-10 hours

### Hour 1-2: Enhanced Backup Management
- Incremental backup implementation
- Backup encryption
- Storage backend abstraction

### Hour 3-4: Automated Backup Scheduling
- Backup automation script
- Schedule configuration
- Validation and alerting

### Hour 5-6: Automated Restore Testing
- Restore test automation
- RTO/RPO measurement
- Test reporting

### Hour 7-8: DR Drill Orchestration
- DR drill script
- Scenario simulation
- Failover testing

### Hour 9-10: Multi-Region Replication & Documentation
- Multi-region backup replication
- DR plan documentation
- Runbooks and monitoring

## Dependencies

### Required Python Packages
- `APScheduler` - Backup scheduling
- `cryptography` - Backup encryption
- `boto3` - AWS S3 integration (optional)
- `azure-storage-blob` - Azure Blob integration (optional)
- `google-cloud-storage` - GCS integration (optional)

### External Dependencies
- PostgreSQL with WAL archiving (for point-in-time recovery)
- S3/Azure Blob/GCS account (for multi-region storage)
- Monitoring system (Prometheus/Grafana)
- Alerting system (email/Slack/PagerDuty)

## Security Considerations

### Backup Encryption
- All backups encrypted at rest using AES-256-GCM
- Encryption keys stored securely (KMS/vault)
- Never store keys with backups

### Access Control
- Backup storage access restricted to service accounts
- Audit logging for all backup operations
- MFA required for manual restore operations

### Network Security
- Encrypted transport (TLS 1.3) for backup replication
- VPC endpoints for cloud storage access
- IP whitelisting for backup operations

## Monitoring and Alerting

### Key Metrics
- Backup success rate (target: 99.9%)
- Backup creation time
- Backup size
- Restore test success rate
- RTO/RPO measurements
- Replication lag

### Alerts
- Backup failures (immediate)
- Restore test failures (immediate)
- RTO/RPO threshold breaches (warning)
- Replication failures (immediate)
- Storage capacity warnings (warning)

## Next Steps

1. Review and approve this implementation plan
2. Set up development environment with required dependencies
3. Implement Phase 1: Enhanced Backup Management
4. Implement Phase 2: Automated Backup Scheduling
5. Implement Phase 3: Automated Restore Testing
6. Implement Phase 4: DR Drill Orchestration
7. Implement Phase 5: Multi-Region Replication
8. Comprehensive testing and validation
9. Documentation finalization
10. Production deployment
