Cloud Migration Strategy Complete Guide 2026

Why Cloud Migration is Companies' Top Priority Now

Cloud computing is no longer "new technology"—it's essential infrastructure for business. According to Gartner, by 2026, 65% of global IT spending will be cloud-related.

However, Japanese companies' cloud adoption rate is 68% (2025), lagging behind Western countries (82%). Meanwhile, companies successful in cloud migration achieve remarkable results: 45% cost reduction, 3x development speed, and 99.9%+ availability.

At Bridge Software Solutions, we've successfully completed over 500 cloud migration projects with a failure rate of only 1.8% (industry average: 23%), boasting high success rates. This article details practical cloud migration strategies.

📊 Cloud Migration Results (Measured Data)

• ✓ Infrastructure Cost: 45% reduction average
• ✓ Development/Deploy Speed: 3.2x improvement average
• ✓ System Availability: 99.92% average achieved
• ✓ Scalability: 10x+ vs. traditional
• ✓ Security Incidents: 67% reduction average
• ✓ Business Continuity: 95% disaster recovery time reduction

1. Six Benefits of Cloud Migration

1. Cost Optimization

Shift from CapEx (capital expenditure) to OpEx (operational expenditure), dramatically reducing initial investment and achieving pay-as-you-go pricing.

Cost Reduction Breakdown

【Traditional On-Premise】
- Server purchase: $210K
- Data center: $84K/year
- Maintenance/ops personnel: $56K/year
- Electricity: $21K/year
━━━━━━━━━━━━━━━━━━━━━━
Initial investment: $210K
Annual ops cost: $161K
5-year total cost: $1.02M

【AWS Cloud After Migration】
- Initial investment: $35K (migration cost)
- AWS fees: $63K/year
- Ops personnel: $28K/year
━━━━━━━━━━━━━━━━━━━━━━
Initial investment: $35K
Annual ops cost: $91K
5-year total cost: $490K

💰 5-year savings: $525K (52% reduction)

2. Agility and Speed

New server procurement from weeks to minutes. Rapidly respond to business changes.

Example: New Project Launch

3. Global Expansion

Deploy to 30+ regions worldwide in minutes. Easily expand global business.

4. Scalability

Automatically scale out during traffic spikes. Handle traffic surges during Black Friday or sales.

// AWS Auto Scaling configuration example
const autoScalingConfig = {
  minInstances: 2,
  maxInstances: 100,
  targetCPUUtilization: 70,
  scaleOutCooldown: 300,
  scaleInCooldown: 300,
};

// Automatically scales from 2 to 100 instances based on traffic

5. Enhanced Security

AWS, Azure, GCP provide world-class security measures. ISO 27001, SOC 2, PCI DSS certified.

6. Business Continuity (BCP)

Multi-region redundancy ensures service continuity during disasters. Reduce RTO (Recovery Time Objective) from hours to minutes.

2. Cloud Provider Selection

AWS (Amazon Web Services)

Market Share: 32% (2025)
Features: Broadest service portfolio, mature ecosystem

Recommended Cases

• ✅ Startups to large enterprises
• ✅ Want to choose optimal solutions from rich services
• ✅ Comprehensive community and documentation
• ✅ Leverage serverless architecture

Key Services

• EC2: Virtual servers
• S3: Object storage
• RDS: Managed database
• Lambda: Serverless functions
• CloudFront: CDN
• EKS: Kubernetes managed service

Azure (Microsoft Azure)

Market Share: 23% (2025)
Features: Strong Microsoft product affinity, hybrid cloud strength

Recommended Cases

• ✅ Heavy Windows Server, Active Directory usage
• ✅ Integration with Office 365, Microsoft 365
• ✅ .NET application execution
• ✅ Rich Japan regions (East/West Japan)

GCP (Google Cloud Platform)

Market Share: 11% (2025)
Features: Strong in AI/ML, big data, user-friendly UI

Recommended Cases

• ✅ AI/machine learning projects
• ✅ Data analysis with BigQuery
• ✅ Kubernetes (GKE) usage
• ✅ Seeking simple, user-friendly UI

Comparison Table

3. Seven Steps of Cloud Migration

Step 1: Current State Analysis & Assessment (2-4 weeks)

Inventory existing systems and determine migration priorities.

Assessment Items

interface SystemAssessment {
  // Technical elements
  architecture: string;           // Monolith/Microservices
  database: string[];             // Databases in use
  dependencies: string[];         // Dependencies
  dataVolume: number;             // Data volume (GB)
  
  // Business elements
  businessCriticality: 1 | 2 | 3; // 1=High 3=Low
  uptime: number;                 // Uptime requirement
  compliance: string[];           // Compliance requirements
  
  // Migration elements
  migrationComplexity: 'Low' | 'Medium' | 'High';
  estimatedCost: number;          // Migration cost estimate
  estimatedDuration: number;      // Migration duration (weeks)
}

Output: Migration Roadmap

【Phase 1】(3 months)
- Static websites → S3 + CloudFront
- Development environment → EC2
- Log management → CloudWatch

【Phase 2】(6 months)
- Web applications → ECS/Fargate
- Database → RDS
- File storage → S3

【Phase 3】(12 months)
- Core systems → Kubernetes (EKS)
- Data warehouse → Redshift
- Backup → S3 Glacier

Step 2: Cloud Architecture Design (3-6 weeks)

Design considering security, scalability, cost efficiency.

Sample Architecture (AWS)

┌──────────────────────────────────────────────┐
│ Route 53 (DNS)                               │
└──────────┬───────────────────────────────────┘
           │
┌──────────▼───────────────────────────────────┐
│ CloudFront (CDN)                             │
└──────────┬───────────────────────────────────┘
           │
┌──────────▼───────────────────────────────────┐
│ Application Load Balancer                    │
└──────────┬───────────────────────────────────┘
           │
    ┌──────┴──────┐
    │             │
┌───▼────┐   ┌───▼────┐
│ ECS    │   │ ECS    │  Auto Scaling
│ Fargate│   │ Fargate│  (2-20 tasks)
└───┬────┘   └───┬────┘
    │             │
    └──────┬──────┘
           │
┌──────────▼───────────────────────────────────┐
│ RDS (Multi-AZ)                               │
│ Primary DB ←→ Standby DB                     │
└──────────────────────────────────────────────┘

Step 3: Select Migration Strategy

Six Migration Strategies (6Rs)

1. Rehost (Lift and Shift)

• Migrate as-is to cloud
• Fastest (weeks to months)
• Cost reduction: 30-40%

2. Replatform

• Implement minor optimizations
• Leverage managed services like RDS
• Cost reduction: 40-50%

3. Refactor

• Redesign cloud-native
• Serverless, microservices
• Cost reduction: 50-60%

4. Repurchase

• Migrate to SaaS (e.g., Salesforce, Slack)
• Rapid migration
• Significant ops reduction

5. Retire

• Decommission unnecessary systems
• Immediate cost reduction

6. Retain

• Continue on-premise
• Compliance or other reasons

Step 4: Security & Compliance Design (2-3 weeks)

AWS Security Best Practices

// Infrastructure as Code (Terraform)
resource "aws_vpc" "main" {
  cidr_block           = "10.0.0.0/16"
  enable_dns_hostnames = true
  enable_dns_support   = true
  
  tags = {
    Name = "production-vpc"
  }
}

// Private subnets (DB, application)
resource "aws_subnet" "private" {
  count             = 2
  vpc_id            = aws_vpc.main.id
  cidr_block        = "10.0.${count.index + 1}.0/24"
  availability_zone = data.aws_availability_zones.available.names[count.index]
}

// Public subnets (ALB only)
resource "aws_subnet" "public" {
  count                   = 2
  vpc_id                  = aws_vpc.main.id
  cidr_block              = "10.0.${count.index + 101}.0/24"
  availability_zone       = data.aws_availability_zones.available.names[count.index]
  map_public_ip_on_launch = true
}

// Security group (principle of least privilege)
resource "aws_security_group" "app" {
  name        = "app-sg"
  description = "Security group for application servers"
  vpc_id      = aws_vpc.main.id

  // Only allow traffic from ALB
  ingress {
    from_port       = 443
    to_port         = 443
    protocol        = "tcp"
    security_groups = [aws_security_group.alb.id]
  }

  // Allow all outbound traffic
  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }
}

Security Checklist

• ✅ IAM: Least privilege principle, MFA enabled
• ✅ Network: VPC, subnet isolation, security groups
• ✅ Encryption: Data encryption (at-rest, in-transit)
• ✅ Logging: CloudTrail, CloudWatch Logs
• ✅ Vulnerability mgmt: AWS Inspector, GuardDuty
• ✅ Backup: Automated backup, snapshots

Step 5: Pilot Migration & Testing (4-8 weeks)

Validate with non-critical systems before production migration.

Test Items

interface MigrationTest {
  performance: {
    responseTime: number;      // Response time
    throughput: number;        // Throughput
    concurrentUsers: number;   // Concurrent users
  };
  
  functionality: {
    apiEndpoints: boolean[];   // API verification
    dbConnections: boolean;    // DB connection check
    fileStorage: boolean;      // Storage check
  };
  
  disaster_recovery: {
    rto: number;               // Recovery time objective (min)
    rpo: number;               // Recovery point objective (min)
    backupRestore: boolean;    // Backup restore test
  };
  
  security: {
    vulnerabilityScan: boolean;
    penetrationTest: boolean;
    complianceCheck: boolean;
  };
}

Step 6: Production Migration (Migration window: typically 4-8 hours)

Migration Checklist

Pre-migration (D-7 days)

• ✅ Notify all stakeholders
• ✅ Final review of migration procedures
• ✅ Prepare rollback procedures
• ✅ Configure monitoring/alerts

Migration Day (D-Day)

20:00 - Start maintenance mode
20:30 - Take final backup
21:00 - Begin database migration
23:00 - Begin application migration
01:00 - DNS cutover
02:00 - Start verification
04:00 - Begin enhanced monitoring period
08:00 - End maintenance mode

Post-migration (D+7 days)

• ✅ Performance monitoring
• ✅ Error rate monitoring
• ✅ Cost monitoring
• ✅ User feedback collection

Step 7: Optimization & Improvement (Continuous)

Continue optimizing cost and performance after migration.

Cost Optimization Strategy

// 1. Reserved Instances (RI) utilization
// 1-year contract: 40% discount
// 3-year contract: 60% discount

// 2. Spot Instances (up to 90% discount)
const spotInstanceConfig = {
  instanceType: 't3.large',
  maxPrice: '0.05',  // 50% of regular price
  interruptionBehavior: 'terminate',
};

// 3. Auto Scaling for resource optimization
const autoScalingPolicy = {
  scaleUpThreshold: 70,    // Scale out at 70% CPU
  scaleDownThreshold: 30,  // Scale in at 30% CPU
  cooldownPeriod: 300,     // 5-min cooldown
};

// 4. S3 Lifecycle policy
const s3Lifecycle = {
  rules: [
    {
      id: 'archive-old-logs',
      prefix: 'logs/',
      transitions: [
        { days: 30, storageClass: 'STANDARD_IA' },    // Infrequent access after 30 days
        { days: 90, storageClass: 'GLACIER' },        // Archive after 90 days
      ],
      expiration: { days: 365 },  // Delete after 1 year
    },
  ],
};

4. Seven Points for Failure Prevention

1. Phased Migration (Avoid Big Bang)

❌ Bad: Migrate everything at once
✅ Good: Phased migration starting with low-priority systems

2. Proper Team Structure

Required roles:

• Cloud Architect: Design lead
• DevOps Engineer: Implementation/automation
• Security Engineer: Security design
• Project Manager: Overall management

3. Cost Visibility & Management

// Monitor costs with AWS Cost Explorer API
import { CostExplorer } from 'aws-sdk';

const ce = new CostExplorer();

async function getDailyCost() {
  const result = await ce.getCostAndUsage({
    TimePeriod: {
      Start: '2026-01-01',
      End: '2026-01-31',
    },
    Granularity: 'DAILY',
    Metrics: ['UnblendedCost'],
    GroupBy: [
      { Type: 'SERVICE', Key: 'SERVICE' },
    ],
  }).promise();
  
  return result;
}

4. Thorough Automation (IaC)

Make environments reproducible with Infrastructure as Code.

# Codify infrastructure with Terraform
terraform {
  backend "s3" {
    bucket = "my-terraform-state"
    key    = "prod/terraform.tfstate"
    region = "ap-northeast-1"
  }
}

# Manage changes with Git, review, deploy

5. Monitoring & Alerting Setup

// CloudWatch alarm configuration
const alarm = {
  alarmName: 'high-cpu-usage',
  comparisonOperator: 'GreaterThanThreshold',
  evaluationPeriods: 2,
  metricName: 'CPUUtilization',
  namespace: 'AWS/EC2',
  period: 300,
  statistic: 'Average',
  threshold: 80,
  actionsEnabled: true,
  alarmActions: ['arn:aws:sns:ap-northeast-1:123456789:alerts'],
};

6. Disaster Recovery Plan

// Multi-Region backup strategy
const drStrategy = {
  primaryRegion: 'ap-northeast-1',      // Tokyo
  secondaryRegion: 'ap-northeast-3',    // Osaka
  
  rto: 15,  // Recover within 15 minutes
  rpo: 5,   // Tolerate up to 5 minutes data loss
  
  backupSchedule: {
    database: 'every 5 minutes',
    files: 'every 1 hour',
    fullBackup: 'daily at 2:00 AM',
  },
};

7. Training & Documentation

• Technical documentation
• Operational procedures
• Team training

5. Major Enterprise Success Story

Manufacturing Company G (12,000 Employees)

🔍 Challenge

• Aging data center (expected $3.5M renewal cost)
• Delayed global expansion
• System downtime losses ($1.4M annually)

💡 Implemented Migration Strategy

Phase 1: Rehost (3 months)

• 100 servers to AWS EC2
• Database migrated to RDS

Phase 2: Replatform (6 months)

• Containerization (ECS Fargate)
• Microservices architecture
• CI/CD pipeline construction

Phase 3: Optimization (Continuous)

• Auto Scaling implementation
• Reserved Instances utilization
• S3 lifecycle optimization

📈 Implementation Results

• Infrastructure cost: $2M annual savings (48% reduction)
• Data center renewal cost: $3.5M investment avoided
• System availability: 95% → 99.95%
• Deploy frequency: Monthly → 10x/week
• Failure recovery time: Average 4 hours → 10 min
• Global expansion: New region launch 6 months → 1 week

"Bridge Software Solutions' cloud migration support transformed not only our systems but our development culture itself. We're grateful for their technical expertise and thorough support."
— Executive Officer, IT Division

Summary | Cloud is Source of Competitive Advantage

Cloud migration brings not just cost reduction, but improved business agility, accelerated global expansion, and innovation promotion.

At Bridge Software Solutions, based on over 500 cloud migration implementations, we propose optimal migration strategies for your business. From assessment to design, migration, and optimization, we ensure success with comprehensive support.

🚀 Next Steps

1. Free cloud assessment (2 weeks) for current state analysis
2. Migration roadmap creation and ROI calculation
3. Pilot migration to validate effects
4. Full migration to cloud-native

Based in Tokyo, serving nationwide. Support for AWS, Azure, GCP. Start with free consultation—contact us today.

💡 FAQ

Q: How long does cloud migration take?
A: Depends on system scale, typically 3-12 months. Phased migration lets you realize benefits early.

Q: Can existing systems migrate as-is?
A: Yes, "Rehost (Lift and Shift)" strategy enables migration with minimal changes.

Q: Is security okay?
A: AWS, Azure, GCP are ISO 27001, SOC 2, PCI DSS certified, achieving security beyond on-premise.