AWS Database Migration Service (DMS) is a fully managed service that enables you to migrate databases to AWS quickly and securely while minimizing downtime. The source database remains fully operational during the migration, reducing disruption to applications that rely on it.
DMS supports homogen…AWS Database Migration Service (DMS) is a fully managed service that enables you to migrate databases to AWS quickly and securely while minimizing downtime. The source database remains fully operational during the migration, reducing disruption to applications that rely on it.
DMS supports homogeneous migrations (such as Oracle to Oracle) and heterogeneous migrations (such as Oracle to Amazon Aurora or Microsoft SQL Server to MySQL). For heterogeneous migrations, you typically use the AWS Schema Conversion Tool (SCT) first to convert the source schema and code to match the target database.
Key features of AWS DMS include:
**Continuous Data Replication**: DMS uses Change Data Capture (CDC) to replicate ongoing changes from the source to the target, ensuring data consistency during migration windows.
**Supported Sources and Targets**: DMS supports various database engines including Oracle, SQL Server, MySQL, PostgreSQL, MongoDB, Amazon S3, Amazon Redshift, Amazon DynamoDB, and more.
**Minimal Downtime**: Applications can continue operating while DMS handles the bulk data load and ongoing replication, with only brief cutover periods required.
**Replication Instances**: DMS uses replication instances to perform migration tasks. You select the instance class based on your workload requirements and data volume.
**Task Types**: You can configure full load migrations, CDC-only migrations, or full load plus CDC for comprehensive data transfer.
**Monitoring and Validation**: DMS integrates with Amazon CloudWatch for monitoring and provides data validation features to ensure source and target data match.
For Solutions Architects, DMS is essential for workload modernization strategies, enabling legacy database migrations to cloud-native services like Amazon Aurora, Amazon RDS, or Amazon Redshift. It reduces complexity and risk while supporting large-scale migration initiatives as part of broader cloud adoption frameworks.
AWS Database Migration Service (DMS) - Complete Guide
Why AWS Database Migration Service is Important
AWS Database Migration Service (DMS) is a critical service for organizations moving to the cloud or modernizing their database infrastructure. It enables seamless migration of databases with minimal downtime, supports heterogeneous migrations between different database engines, and allows continuous data replication. For the AWS Solutions Architect Professional exam, DMS represents a key component in migration and modernization strategies.
What is AWS Database Migration Service?
AWS DMS is a managed service that helps you migrate databases to AWS quickly and securely. The source database remains fully operational during the migration, minimizing downtime to applications that rely on the database.
Key Features: • Supports homogeneous migrations (Oracle to Oracle) and heterogeneous migrations (Oracle to Aurora) • Continuous data replication with Change Data Capture (CDC) • Supports on-premises to cloud, cloud to cloud, and cloud to on-premises migrations • Works with most widely used commercial and open-source databases • Pay only for compute resources and log storage used during migration
How AWS DMS Works
Core Components:
1. Replication Instance: An EC2 instance that runs replication tasks. Size it based on the amount of data and number of tasks.
2. Source Endpoint: Connection information for your source database (on-premises, EC2, or RDS).
3. Target Endpoint: Connection information for your destination database in AWS.
4. Replication Task: Defines what data to migrate and how to migrate it.
Migration Types: • Full Load: Migrates existing data from source to target • CDC Only: Replicates only data changes • Full Load + CDC: Migrates existing data and then continues replicating changes
AWS Schema Conversion Tool (SCT)
When performing heterogeneous migrations, use AWS SCT to convert the source database schema and code to a format compatible with the target database. SCT handles stored procedures, functions, views, and triggers conversion.
When SCT is Required: • Oracle to PostgreSQL • SQL Server to MySQL • Oracle to Amazon Aurora
When SCT is NOT Required: • MySQL to Amazon Aurora MySQL • PostgreSQL to Amazon RDS PostgreSQL • Homogeneous migrations
Key Use Cases
1. Database Consolidation: Combine multiple source databases into a single target 2. Continuous Replication: Keep databases synchronized for disaster recovery 3. Development and Testing: Replicate production data to test environments 4. Database Migration: Move from on-premises to AWS or between AWS services
DMS with Other AWS Services
• AWS Snowball Edge: For large-scale migrations where network bandwidth is limited, use Snowball Edge with DMS for initial data transfer • Amazon S3: DMS can use S3 as a source or target for data migration • Amazon Kinesis: Stream database changes to Kinesis Data Streams • Amazon Redshift: Migrate data warehouse workloads to Redshift
Exam Tips: Answering Questions on AWS Database Migration Service
Tip 1: Know When to Use SCT If the question involves migrating between different database engines (heterogeneous), AWS SCT is required for schema conversion. Homogeneous migrations do not require SCT.
Tip 2: Understand Replication Instance Sizing Questions about slow migrations or replication lag often point to undersized replication instances. Multi-AZ replication instances provide high availability.
Tip 3: Recognize CDC Requirements For minimal downtime migrations, look for answers that combine Full Load with Change Data Capture (CDC). This allows continuous synchronization during cutover.
Tip 4: Large Database Migrations When questions mention very large databases (terabytes) with limited bandwidth, the solution typically involves AWS Snowball Edge for initial load combined with DMS for CDC to capture ongoing changes.
Tip 5: Security Considerations DMS supports encryption at rest and in transit. For sensitive data migrations, look for answers mentioning SSL connections and KMS encryption.
Tip 6: Target Database Selection Know that DMS supports migration to Aurora, RDS, Redshift, DynamoDB, S3, and more. Match the target database to the workload requirements in the question.
Tip 7: Validation AWS DMS provides data validation features to ensure source and target data match. This is important for compliance and audit requirements.
Common Exam Scenarios: • Migrating Oracle to Aurora with minimal downtime = DMS + SCT + Full Load with CDC • Large data warehouse migration = Snowball Edge + DMS CDC • Keeping on-premises and cloud databases synchronized = DMS continuous replication • Converting stored procedures during migration = AWS Schema Conversion Tool