4.2.1. Database Migration Service (DMS)

💡 First Principle: AWS Database Migration Service (DMS) facilitates secure, rapid database migration to AWS. It supports homogeneous and heterogeneous migrations with minimal downtime, enabling organizations to leverage cloud database benefits.

AWS Database Migration Service (DMS) is a fully managed service that simplifies and accelerates the migration of databases to AWS. It supports migrating data between various database engines.

Key Capabilities of DMS:

• Homogeneous Migrations: Migrating between the same database engines (e.g., MySQL to Amazon RDS for MySQL).
• Heterogeneous Migrations: Migrating between different database engines (e.g., Oracle to Amazon Aurora PostgreSQL-compatible). AWS Schema Conversion Tool (SCT) helps with schema and code conversion for these.
• One-Time Data Migration: Migrates a snapshot of the source database to the target.
• "Continuous Data Replication (CDC)": Enables ongoing synchronization between source and target databases, allowing for minimal downtime migrations. This is critical for production databases.

Scenario: An on-premises Oracle database is migrated to Amazon Aurora PostgreSQL using DMS, leveraging continuous data replication for minimal disruption during the transition.

Visual: AWS Database Migration Service (DMS) Flow

Key Trade-Offs:

• Full Load vs. CDC: Full Load is simpler but requires more downtime. CDC minimizes downtime but adds complexity by continuously replicating changes.

Reflection Question: How does DMS's ability to handle heterogeneous migrations (e.g., Oracle to PostgreSQL) and provide continuous data replication fundamentally impact cloud adoption strategies for diverse database environments requiring minimal downtime?

⚠️ Exam Trap: Know when SCT is required vs DMS alone:

Key Concepts: Full load + CDC (Change Data Capture) provides minimal-downtime migration. DMS can also target S3, Kinesis, and DynamoDB for modernization patterns. Run the SCT Assessment Report first to estimate manual conversion effort.