AWS Database Migration Service

AWS Database Migration Service (AWS DMS) is a managed service from Amazon Web Services (AWS) that allows you to replicate and migrate databases easily, securely, and without data loss. DMS supports homogeneous migrations, such as from Oracle to Amazon RDS for Oracle, and heterogeneous migrations (between different database platforms) such as from Oracle or Microsoft SQL Server to Amazon Aurora.

How does the AWS DMS work?

With AWS DMS you can choose on-demand instances or use serverless technology. AWS Database Migration Service Serverless automatically provisions and manages capacity. During migration, changes made to the source database are continuously replicated to the destination. Therefore, the source database remains operational during the migration, minimizing downtime for applications that depend on the database.

After the migration is complete, the destination database remains synchronized with the source database for as long as determined, allowing the transition to the database to occur at the appropriate time.

Support is offered for a variety of scenarios, such as: Oracle to Amazon Aurora (MySQL compatible), MySQL to Amazon Relational Database (RDS) for MySQL, Microsoft SQL Server to Amazon Aurora (PostgreSQL compatible), MongoDB to Amazon DocumentDB (MongoDB compatible), Oracle to Amazon Redshift, and Amazon Simple Storage Service (S3).

Best practices with AWS DMS 

It is essential to carry out a detailed analysis of the characteristics of the environment and workloads to define the most appropriate migration strategy. Careful planning is also required, including choosing the right endpoints, configuring migration tasks, and defining data transformations if necessary. 

Migration testing in a suitable environment is a relevant activity before carrying out the migration in production. This way, you can validate the functionality of the data and adjust the settings, if applicable. 

During migration, monitoring migration tasks and related events are essential factors for identifying possible occurrences and ensuring the success of the migration.

Billing and Free Tier 

AWS Database Migration Service (DMS) has a usage-based payment model. Costs are calculated based on factors such as the type and size of replication instances used, the amount of data transferred, and the AWS region selected for migration. 

The free tier currently includes up to 750 hours of Single-AZ dms.t2.micro instance usage per month for one year.  In On-Demand Instance mode, there is a cost for the replication instances and any additional log storage.