On-Prem to Cloud Migration Process

A comprehensive guide to migrating your on-premises infrastructure to AWS cloud, with detailed steps and considerations for minimal downtime.

1. Plan the Migration

  • Assessment: Identify current environment (servers, databases, dependencies, configurations)
  • Inventory: Document application components and dependencies
  • Sizing: Determine AWS resources based on current usage
  • Network Design: Plan VPC setup, subnets, security groups, connectivity
  • Backup Plan: Create fallback strategy for migration issues

2. Prepare the AWS Environment

  • VPC Setup: Create VPC with multi-AZ subnets
  • Security: Configure security groups, IAM roles, policies
  • Database Configuration: Set up RDS or EC2-based database
  • AD Server: Deploy AWS Managed Microsoft AD or EC2-based AD
  • Application Server: Launch and configure EC2 instances

3. Migrate Database

  • Backup: Create current database backup
  • Export/Import: Use AWS DMS or native tools for migration
  • Replication: Set up real-time sync with on-prem database
  • Validation: Verify data consistency and integrity

4. Migrate Application Server

  • Packaging: Package application (Docker, AMIs, binaries)
  • Deployment: Deploy on EC2 or Elastic Beanstalk
  • DNS Configuration: Update DNS records for AWS environment

5. Migrate Active Directory

  • Replication: Create AD replica in AWS using Trust setup
  • DNS Sync: Synchronize DNS entries between environments
  • Validation: Test authentication and resource access

6. Test and Validate

  • End-to-End Testing: Validate complete environment
  • Performance Check: Monitor with CloudWatch
  • Failover Testing: Simulate failure scenarios

7. Cutover and Go Live

  • Schedule Downtime: Coordinate minimal downtime window
  • Final Sync: Perform final database sync and traffic switch
  • DNS Propagation: Update DNS settings (up to 24 hours)
  • Monitoring: Continuous post-migration monitoring

8. Post-Migration Optimization

  • Scaling: Implement auto-scaling policies
  • Security: Regular security review and improvement
  • Cost Optimization: Analyze and optimize with AWS Cost Explorer

Downtime Considerations

  • Database Migration: 2-4 hours maintenance window for final sync and cutover
  • DNS Propagation: 15 minutes to 24 hours (depending on TTL settings)
  • Tip: Use short TTLs during migration to minimize delays