AWS Database Migration Service Cheat Sheet

• AWS Database Migration Service (DMS) is a managed service that helps you migrate databases to AWS quickly and securely. The source database remains fully operational throughout the migration, minimizing downtime for applications that rely on it.
• Supports homogeneous migrations such as Oracle to Oracle, as well as heterogeneous migrations between different database platforms, such as Oracle or Microsoft SQL Server to Amazon Aurora.

• You can use Database Migration Service for one-time data migration into RDS and EC2-based databases.
• You can also continuously replicate your data with high availability (enable multi-AZ) and consolidate databases into a petabyte-scale data warehouse by streaming data to Amazon Redshift and Amazon S3.
• Continuous replication can be done from your data center to the databases in AWS or the reverse.
• Replication between on-premises to on-premises databases is not supported.
• The service provides an end-to-end view of the data replication process, including diagnostic and performance data for each point in the replication pipeline.
• Supports transaction commit date partitioning in CDC Mode when you select Amazon S3 as a target. You can write data from a single source table to a time-hierarchy folder structure in Amazon S3.

Terminology and Concepts

• • High-level view:
    • AWS DMS runs replication software in the AWS Cloud to move data. You define connections (endpoints), provision compute resources, and create a task to move the data.
  • Replication Instance:
    • A managed EC2 instance that hosts the replication software and processes the data changes.
  • Endpoints:
    • Configuration objects that store connection information (IP, port, credentials) for your data stores.
  • Replication Task:
    • A user-defined job that specifies what data to migrate and how (e.g., Full Load, CDC).
  • Amazon Resource Names (ARNs):
    • Uniquely identify DMS resources.
    • Uses the syntax: arn:aws:dms:region:account number:resourcetype:resourcename
  • Integration:
    • Works with AWS KMS for encryption, AWS IAM for access control, and AWS Secrets Manager to secure database credentials.

• Key Features

  • AWS DMS Fleet Advisor:
    • A free, fully managed capability that automatically inventories your on-premises database and analytics servers. It provides “right-sized” recommendations for migrating them to AWS, helping you plan migrations at scale without manual spreadsheet tracking.
    • Note: AWS has announced that support for DMS Fleet Advisor will end on May 20, 2026.
  • Premigration Assessments:
    • Validates your source and target databases against a set of rules before the migration starts to identify potential failures (e.g., unsupported data types).
  • Enhanced Monitoring:
    • A centralized dashboard providing comprehensive visibility into migration task health, table statistics, and performance metrics.

• Deployment Options

  • DMS Standard:
    • You manually provision and manage a Replication Instance (e.g., dms.t3.medium). You are responsible for sizing the instance and managing storage.
  • DMS Serverless:
    • Automatically provisions, monitors, and scales migration resources (capacity units) to match workload demand. Best for sporadic or unpredictable data spikes.
  • Homogeneous Data Migrations:
    • A fully managed, serverless option specifically for like-to-like migrations (e.g., MySQL to RDS MySQL) using native database tools for maximum performance.

AWS Schema Conversion Tool (SCT)

• • The AWS Schema Conversion Tool makes heterogeneous database migrations predictable by automatically converting the source database schema and a majority of the database code objects, including views, stored procedures, and functions, to a format compatible with the target database.
  • SCT can also scan your application source code for embedded SQL statements and convert them as part of a database schema conversion project.
  • Supported migrations

Basic Schema Copy

• • To quickly migrate a database schema to your target instance you can rely on the Basic Schema Copy feature of AWS Database Migration Service.
  • Basic Schema Copy will automatically create tables and primary keys in the target instance if the target does not already contain tables with the same names.
  • It will not migrate secondary indexes, foreign keys or stored procedures. When you need to use a more customizable schema migration process, use AWS SCT.

AWS Database Migration Service Pricing

• DMS Standard: You only pay for the compute resources used during the migration process and any additional log storage. Each database migration instance includes storage sufficient for swap space, replication logs, and data cache for most replications, and inbound data transfer is free.
• DMS Serverless: Charged based on DMS Capacity Units (DCUs) used per hour. One DCU equals 2GB of RAM.
• Homogeneous Data Migrations: Charged strictly by the hour for the duration of the migration service usage.

Note: If you are studying for the AWS Certified Data Engineer Associate exam, we highly recommend that you take our AWS Certified Data Engineer Associate Practice Exams and read our Data Engineer Associate exam study guide.

AWS Database Migration Service Cheat Sheet Resources:

https://aws.amazon.com/dms/

https://aws.amazon.com/dms/schema-conversion-tool/

https://aws.amazon.com/dms/faqs/

https://docs.aws.amazon.com/dms/latest/userguide/Welcome.html