What is AWS Database Migration Service (AWS DMS)?

Moving databases to the cloud can be a really challenging and risky process, and it can also interrupt business processes. But if the right tools and services are employed, a lot of time is saved and the process is made easy. Indeed, one of the solutions that has evolved into a best practice for organizations actively seeking a way to update the organization’s data architecture is the AWS Database Migration Service, or AWS DMS abbreviation.

In this blog, you will learn in detail about the AWS DMS service, including its workings, implementation scenarios, and how it can be of value to your business. This fully managed service makes it easier to migrate databases to the cloud, from on-premises, or from one cloud service to another.

Now, you will be in a better position to realize the issues associated with the database migration and assess if AWS DMS is the right option. If you are looking to deepen your knowledge, consider enrolling in our comprehensive AWS Course. Therefore, let’s begin and demystify how AWS DMS can help with your cloud migration process.

What is AWS Database Migration Service?

AWS Database Migration Service, or DMS, is 100% AC software that helps organizations move databases to the AWS cloud. It backs up and restores relational DBMS, NoSQL, data warehouses, and any other data repository types. DMS migrations are done with minimal source database interruption, and database copies of source databases can remain active during the cutover.

Currently, the service offers both structured transfers, including Oracle-Oracle or Microsoft SQL Server-Aurora, and unstructured transfers. DMS carefully handles all the issues of the transfer process, thereby achieving accuracy in the new system. It is most suitable for organizations that want to migrate to cloud infrastructure without the inconvenience. If you’re new to AWS, you might want to read What is AWS first to get a foundational understanding.

How Does AWS Database Migration Service Work?

AWS DMS helps in this process by providing the extraction, copying, and transfer of data between source and target databases. The process starts with the definition of the endpoints of the source and target databases.

These endpoints describe how the application should connect to the particular database type, including the credentials as well as the locations of the servers. After endpoints are set, a structure of replication is initiated. This instance actually undertakes the physical data transfer, and it is a managed Amazon EC2 instance.

The replication process starts with the full dump load, where all the information from the source database is transferred to the replication agent. In this stage, it is possible to keep using the source database for additional transactions, whereas new transactions are performed at the target database. These changes are tracked and cached by DMS through what is known as change data capture (CDC). Once all the work in the full loads is done, DMS turns to the cache at the target database and writes the changes there in order to make the two databases identical.

AWS DMS also has a real-time monitoring option, so you can see how your migration is going and address any problems if there are any. The service also enables constant data replication, which means that it is a perfect solution to synchronize on-premises and cloud databases daily. While most of the complex process of data migration is handled by AWS DMS, it helps reduce the risk of errors and time for the migration process.

Components of AWS Database Migration Service

AWS DMS consists of three key components that work together to facilitate database migration:

1. Replication Instance: This is an instance for the replication of DMS that uses the Amazon EC2 software. A replication instance extracts data from the source database, processes the data if necessary to adapt to the target, and then inserts the data into the latter. The scalar of a replication instance can be configured relative to the complexity as well as the volume of data transfer.
2. Source and Target Endpoints: The endpoint specifies the source and target databases that will be affected by the migration process. For each endpoint, users will need to provide additional settings such as the database engine type, credentials, server name, and port number. AWS DMS applies to multiple databases engines, such as MySQL, PostgreSQL, Oracle, and Microsoft SQL Server.
3. Replication Tasks: These tasks determine what sort of migration is to be executed and the overview that contains the tables, schemas, and data types to be transferred. The replication tasks can be created as full load migration for copying schema and tables with their data at once or replicating tables with the activation of change data capture (CDC). Tasks also include the possibility of scheduling migrations and checking the status of running ones. To see a step-by-step guide on AWS, check out our AWS Tutorial.

By understanding these components, you can configure AWS DMS to meet your specific migration needs, ensuring a smooth and efficient transition to the cloud.

Use Cases of AWS DMS

• Homogeneous Migrations: This has to do with moving databases that are on the same engines, for instance, from Oracle to Amazon RDS (Oracle) or MySQL to Amazon RDS (MySQL). Homogeneous migrations do not pose much difficulty because the definitions do not change from one database to the next in terms of schema and data types, respectively.
• Heterogeneous Migrations: In this capability, you replicate databases with different engine types, for instance, SQL Server to Aurora or Oracle to PostgreSQL. Some migrations are heterogeneous, and before the data can be transferred, all the schema and code must be transformed. To achieve such a transition, the AWS Schema Conversion Tool (SCT) is typically employed in conjunction with DMS.
• Continuous Data Replication: AWS DMS supports continuous replication, which is suitable for cases when data must be transferred from on-premise databases and AWS DB instances.

When to Use AWS DMS

AWS DMS is suited in such cases where you have little time that the systems can be down while seeking to achieve a high and secure rate of data migration. This is appropriate when an organization is transitioning from an on-premise database solution to a cloud-based solution, especially when dealing with volume or complex issues.

AWS DMS can also help increase the synchronization frequency of data replication jobs, in which both the source and target databases should always be synchronized. Whether you are planning to migrate to Amazon RDS, Aurora, or Redshift, AWS DMS is your ideal option for database migration.

Benefits of AWS Database Migration Service

• Minimal Downtime: AWS DMS also provides the release from using the original database in migration and, as an effect, minimizes or eliminates the outage times in business.
• Cost-effective: DMS, on the other hand, uses a usage-based model; companies only pay for the services they wish to transfer to the cloud.
• Supports Multiple Database Engines: DMS employs MySQL, PostgreSQL, Oracle, MS SQL, and other Database engines besides Amazon Web Services platform’s Redshift and DynamoDB.
• Automated and Managed: DMS is intended to accomplish numerous difficult migration duties, including data replication, monitoring and error checking. This is less likely to be abused by humans, and also makes the migration process to be easier.
• Reliable and Secure: You will be glad to know that AWS DMS offers native security features and high availability features that will allow for smooth and secure data migration while having minimal downtimes.

Limitations of AWS DMS

• Nevertheless, relevant is that AWS DMS does not migrate schema or code when operating heterogenic migration by default. The actual mapping and transformation work will be performed using the AWS SCT tool, and a small percentage of manual intervention could be required to map the complex schemas.
• Performance Constraints: Although designed to support parallel transfer of data, in some cases, for large datasets and high-speed data streams, DMS may develop bottlenecks.
• Coding Requirements: As for some extended options, like CDC and data transformations, they may be implemented with the help of code and, therefore, the migration of the extractor will be complicated.
• Limited Support for Some Data Types: When a shift from a proprietary platform occurs, AWS DMS may not always support all types of data or database functionalities.

Conclusion

AWS Database Migration Service is a relatively general service to help databases move to the cloud. That is why the fact that both homogeneous and heterogeneous migrations are supported while downtime and security are maximal is unambiguous: this is a tool for organizations that need to upgrade their infrastructure.

FAQs

What is AWS DMS used for?

AWS DMS is for the migration of databases to AWS, where the downtime is extremely low and continuous replication of data occurs. If you’re preparing for an AWS-related interview, you might find these AWS Interview Questions helpful.

Is AWS DMS an ETL tool?

No, AWS DMS is specifically designed to handle migration and replication of the data and not much into complex ETL operations.

Is AWS DMS fully managed?

Indeed, AWS DMS is serverless and manages the infrastructure, replication, and migration on behalf of the user.

What are DMS tasks?

DMS tasks describe the nature and specifics of the data transfer that are, tables and data to be transferred.