Zero Downtime Database Migration from On-Prem to AWS RDS Using DMS
Database migration is a critical task for organizations moving towards cloud adoption, modernization, or disaster recovery planning.
1. Problem Statement
Situation
You are working as a Cloud Engineer for an organization that is undergoing cloud modernization. The organization currently hosts its production database (MySQL) in an on-premises data center. Due to high operational costs, scalability issues, and maintenance overhead, the management has decided to migrate this database to Amazon Web Services (AWS) using Amazon RDS (Relational Database Service).
The challenge is that the production database is actively used by multiple applications 24x7. Downtime must be kept to an absolute minimum (near-zero downtime preferred) during the migration, as even a few minutes of disruption could lead to revenue loss and customer dissatisfaction.
Additionally, the data is highly sensitive, containing Personally Identifiable Information (PII), financial records, and operational data. The migration must comply with internal security policies and regulatory compliance, requiring that the data be encrypted both in transit and at rest.
The database is also large (multiple terabytes) and highly transactional, with hundreds of inserts, updates, and deletes happening every second.
Business Requirements
The migration must be completed with minimal to no downtime.
The data must be fully replicated (including CDC — Change Data Capture).
The data transfer must be secure, encrypted, and auditable.
Schema conversion and data type compatibility must be ensured.
The migration process must be monitored, logged, and verifiable.
The target database in Amazon RDS should be ready for production cutover immediately after migration.
The migration process should be documented and reusable for future projects.
Technical Requirements
Use AWS Database Migration Service (AWS DMS) for data replication.
Use AWS Schema Conversion Tool (AWS SCT) if there are schema or data type differences.
Both full load and ongoing replication (CDC) should be performed.
Ensure network connectivity between on-premises and AWS using VPN or Direct Connect.
Setup CloudWatch monitoring and DMS CloudTrail logs for auditing.
Handle potential issues such as:
Data type mismatches
Large LOBs (Large Objects)
Network interruptions
Permission-related errors
Use end-to-end encryption for data transfer.
Key Challenges
Avoiding downtime during the switch-over.
Migrating large volume of data under tight migration window.
Ensuring data consistency and integrity during and after migration.
Handling schema conversions and unsupported data types.
Designing a rollback or disaster recovery plan in case of migration failure.
Expected Outcome
At the end of the migration:
All data, including real-time changes, should be available in Amazon RDS.
Applications should seamlessly switch to using the AWS RDS database.
All security, performance, and reliability goals should be met.
Complete documentation of the process, configurations, and lessons learned should be available.
2. Why We Need This Use Case
Database migration is a critical task for organizations moving towards cloud adoption, modernization, or disaster recovery planning. Manually migrating databases is time-consuming, error-prone, and can cause long downtime. AWS Database Migration Service (DMS) offers a highly reliable and cost-effective solution to migrate production databases to AWS with minimal downtime and disruption. It simplifies the process of moving data from on-premises, other cloud providers, or even between AWS database services. Additionally, DMS supports heterogeneous database migrations, meaning you can migrate from Oracle to PostgreSQL, MySQL to Amazon Aurora, and more. It is also highly valuable for continuous data replication and building data warehouses for analytics. This use case ensures that organizations experience seamless data migration while preserving data integrity.
3. When We Need This Use Case
You would need this use case in the following scenarios:
When migrating databases from on-premises infrastructure to AWS Cloud (for example, moving from an in-house Oracle database to Amazon RDS).
When modernizing legacy databases by switching to AWS-native database engines (e.g., SQL Server to Amazon Aurora).
When consolidating databases during a merger, acquisition, or infrastructure reorganization.
When building a disaster recovery site with real-time database replication on AWS.
When setting up analytics platforms or data warehouses by replicating data into Amazon Redshift or Amazon S3.
When you want to create a hybrid or multi-cloud architecture by synchronizing databases across environments.