Migrating legacy systems to the cloud is one of the most impactful yet challenging undertakings for any organization. In Bangladesh's rapidly growing IT sector, businesses are increasingly recognizing that on-premises infrastructure limits their ability to scale, innovate, and compete globally. At Nexis Limited, we have guided numerous organizations through cloud migration journeys, from initial assessment to post-migration optimization.
The Migration Assessment Framework
Every successful migration begins with a thorough assessment of existing systems. Catalog all applications, their dependencies, data volumes, compliance requirements, and current performance characteristics. AWS provides tools like Migration Hub and Application Discovery Service to automate this inventory. Classify each application using the 7 Rs framework: Retire, Retain, Rehost, Relocate, Repurchase, Replatform, or Refactor. Not every system needs to move to the cloud, and some are better retired or replaced entirely.
Understanding your current total cost of ownership is critical for building a credible business case. Include not just hardware costs but also power, cooling, physical security, maintenance contracts, and the opportunity cost of engineering time spent on infrastructure management rather than product development.
Lift-and-Shift: Speed Over Optimization
Rehosting, commonly called lift-and-shift, moves applications to the cloud with minimal changes. Virtual machines become EC2 instances, on-premises databases move to RDS, and file shares migrate to EFS or S3. This approach is fast and low-risk since the application architecture remains unchanged. It is ideal for applications with upcoming end-of-life dates, compliance deadlines, or data center lease expirations. However, lift-and-shift rarely delivers the full cost benefits of cloud computing because applications are not optimized for cloud-native services.
Replatforming: The Middle Ground
Replatforming makes targeted modifications during migration to take advantage of managed services without a full re-architecture. Examples include migrating a self-managed MySQL database to Amazon RDS, replacing a custom caching layer with ElastiCache, or containerizing a monolithic application for ECS deployment. This approach delivers meaningful operational improvements with moderate effort and risk.
Database Migration Considerations
Database migration is often the most complex aspect of cloud migration. AWS Database Migration Service supports both homogeneous migrations (Oracle to RDS Oracle) and heterogeneous migrations (Oracle to PostgreSQL). For heterogeneous migrations, schema conversion tools help translate stored procedures and data types, but manual intervention is almost always required. Plan for extensive testing of migrated databases, particularly around data integrity, query performance, and application compatibility.
Re-Architecture: Maximum Cloud Benefits
Refactoring or re-architecting means redesigning applications to be cloud-native, leveraging microservices, serverless functions, managed databases, and event-driven patterns. This delivers the greatest long-term benefits in terms of scalability, resilience, and operational efficiency but requires the most investment and carries the highest risk. Reserve re-architecture for strategically important applications that will be actively developed for years to come.
Cost Planning and Optimization
Cloud cost management begins before migration, not after. Use the AWS Pricing Calculator to model costs for each migration approach. Account for data transfer costs, which can be substantial during migration. Implement tagging standards from day one to enable cost allocation by team, project, and environment. Reserved Instances and Savings Plans can reduce compute costs by 30-60% for predictable workloads. Set up billing alerts and anomaly detection to catch unexpected cost increases early.
Risk Mitigation and Rollback Planning
Every migration plan must include a rollback strategy. Maintain the ability to revert to on-premises systems for a defined period after migration. Run parallel systems during the transition to validate data consistency and performance. Migrate non-critical systems first to build team confidence and identify unexpected issues before tackling mission-critical workloads.
Cloud migration is a journey, not a one-time event. Nexis Limited partners with organizations throughout this journey, from initial assessment to ongoing optimization. Our teams have deep experience with AWS services and migration tooling. Explore our services or contact us to start planning your migration strategy.