Moving your company’s databases can feel like a monumental task. The thought of downtime, data loss, or complex technical hurdles is enough to give any IT leader pause. For years, businesses felt locked into their on-premise databases, fearing the disruption that a migration to the cloud

could cause. But what if you could move your entire database to the cloud, seamlessly and securely, with almost no interruption to your daily operations?

That’s where the AWS Database Migration Service, or AWS DMS, comes in. This powerful tool from Amazon Web Services is designed to take the pain and complexity out of database migration. It’s a managed service that helps you move your data reliably and with minimal downtime. For companies looking to modernize their infrastructure and take advantage of the scalability, cost-efficiency, and performance of the cloud, understanding AWS DMS is a game-changer.

What is AWS Database Migration Service?

So, what exactly is AWS DMS? Think of it as a specialized moving service for your data. AWS DMS helps you move your databases to and from AWS quickly and securely. One of its most powerful features is that it keeps your source database fully operational during the migration process. This means your applications that rely on the database can continue running without interruption, minimizing downtime that could affect your customers and your revenue.

AWS DMS can migrate your data between different types of databases. This is called heterogeneous migration. For example, you could move from an Oracle database running in your own data center to an Amazon Aurora Serverless v2 database in the cloud. DMS handles the complex work of converting the database schema and data types to match the new target database. Of course, it also supports homogeneous migrations, where you’re moving between the same type of database, like from a self-hosted MySQL server to Amazon RDS for MySQL.

The service supports a wide range of popular databases, including:

  • Commercial Databases: Oracle, Microsoft SQL Server
  • Open-Source Databases: MySQL, PostgreSQL, MariaDB
  • NoSQL Databases: MongoDB, Amazon DynamoDB
  • Cloud-native Databases: Amazon Aurora, Amazon Redshift

This flexibility makes AWS DMS a versatile tool for almost any database migration project

When Should Your Business Use AWS DMS?

AWS DMS is a versatile tool that fits a wide range of migration scenarios. If your organization finds itself in any of the following situations, AWS DMS is likely the right solution for you.

Moving from On-Premise to the AWS Cloud

This is one of the most common uses for AWS DMS. Many companies are looking to escape the high costs and maintenance overhead of running their own data centers. DMS provides a straightforward path to move databases from your local servers directly into AWS services like Amazon RDS (Relational Database Service) or Amazon Aurora. This allows you to benefit from the scalability, reliability, and security of the AWS cloud.

Migrating Between Different Database Engines

Sometimes, a migration isn’t just about changing the location of your database but also about changing the database engine itself. This is known as a heterogeneous migration. For example, you might want to move from a commercial database like Oracle or Microsoft SQL Server to a more cost-effective, open-source alternative like PostgreSQL or MySQL running on AWS.

These types of migrations can be complex because the structure, data types, and code of the source and target databases are different. AWS DMS, when used with the AWS Schema Conversion Tool (SCT), simplifies this process. The SCT analyzes your source database schema and automatically converts most of it to a format compatible with your target database. It highlights any parts that need manual attention, taking much of the guesswork and manual effort out of the conversion.

Consolidating Multiple Databases

Over time, it’s common for businesses to end up with several different databases supporting various applications. Managing and maintaining all of these can become a significant operational burden. AWS DMS can be used to consolidate multiple source databases into a single, more powerful target database on AWS. For instance, you could merge several smaller MySQL databases into a larger Amazon Aurora instance, simplifying management and reducing costs.

Continuous Data Replication for Analytics or Disaster Recovery

AWS DMS isn’t just for one-time migrations. Its continuous data replication capabilities make it a valuable tool for ongoing tasks. You can use it to replicate data from your live, operational database to a data warehouse like Amazon Redshift for real-time analytics without impacting the performance of your primary application. Similarly, you can replicate your database to another AWS region for disaster recovery purposes, ensuring business continuity in the event of an outage.

Different Types of Migrations You Can Perform

AWS DMS is not a one-size-fits-all tool. It offers flexibility to match your specific project needs. There are three primary ways it can move your data.

1. Full Load Migration

This is the most straightforward type of migration. AWS DMS connects to your source database, copies all the existing data from the tables you specify, and moves it over to the target database. It’s like packing up everything in the old house in one go and moving it to the new one. This approach is perfect for when you can afford some downtime or for initial data seeding.

2. Ongoing Replication (Change Data Capture)

After the initial move, what happens if new data is added or old data is changed in the source database? This is where Change Data Capture (CDC) comes in. After the full load is complete, AWS DMS can stay connected to your source database and watch for any changes. As soon as a change is made, it captures that change and applies it to your target database. This keeps your source and target databases in sync. This method is fantastic for migrations that require minimal downtime, as your applications can keep running on the source while the data is being replicated in near real-time.

3. Full Load Plus CDC

This is the most common and powerful approach. It combines the first two methods. The migration task starts by performing a full load of all existing data. Once that’s done, it automatically switches to CDC mode to capture and apply any changes that happened during the full load process and any new changes going forward. This ensures your target database is a complete and up-to-date replica of the source, allowing you

 to switch over your applications with confidence and very little interruption.

A Step-by-Step Guide to Your First AWS Database Migration

Now let’s walk through the high-level steps you would take to perform a migration using AWS DMS. While every migration is unique, the general workflow remains consistent.

Step 1: Planning and Preparation

Before you do anything in the AWS Console, you need a solid plan.

  • Analyze your source database: Understand its size, workload patterns, and any special features you use.
  • Choose your target database: Decide which AWS database service best fits your needs for performance, scalability, and cost.
  • Use the AWS Schema Conversion Tool (SCT): If you’re doing a heterogeneous migration (e.g., SQL Server to PostgreSQL), run the SCT first. It will analyze your source schema and generate a report detailing what can be converted automatically and what might need manual changes. It then converts and applies the schema to your target database.
  • Set up networking: Ensure your replication instance can connect to both your source and target endpoints. This might involve configuring VPC security groups, network ACLs, and VPNs or AWS Direct Connect for on-premise sources.

Step 2: Create a Replication Instance

In the AWS DMS console, your first action is to create a replication instance. You’ll need to choose an instance class (e.g., dms.t3.medium, or newer Graviton-based options like dms.r6g) depending on your workload. For production migrations, it’s a good practice to enable the Multi-AZ option for high availability.

Step 3: Define Source and Target Endpoints

Next, you’ll create the source and target endpoints. For each, you’ll provide the database engine type, server name or IP address, port number, and the username and password for an account with the necessary permissions to read from the source and write to the target. Before proceeding, use the “Test connection” feature in the console to verify that the replication instance can successfully communicate with both databases.

Step 4: Create and Run the Migration Task

This is where you define the migration itself.

  • Give your task a name.
  • Select the replication instance, source endpoint, and target endpoint you created.
  • Choose the migration type: “Migrate existing data” (full load), “Migrate existing data and replicate ongoing changes” (full load + CDC), or “Replicate data changes only” (CDC only).
  • In the Task settings, you can customize things like logging and error handling.
  • Under Table mappings, you specify which schemas and tables you want to migrate. You can use wildcards (e.g., sales.%) to include all tables in a schema. You can also add transformation rules to rename schemas or tables during the migration.

Once you’ve configured the task, you can start it immediately or save it to run later.

Step 5: Monitor and Validate

After you launch the task, you can monitor its progress from the DMS console. You’ll see metrics for the full load phase, such as the number of tables loaded and the time elapsed. For CDC tasks, you’ll see the replication latency, which tells you how far behind the target is from the source (usually just a few seconds).

Once the full load is complete and CDC is running smoothly, it’s time to validate the data. You can perform queries on both the source and target databases to ensure the data matches. AWS DMS also has a validation feature that can automatically compare the data for you and report any discrepancies.

Step 6: The Cutover

For a minimal-downtime migration, the final step is the cutover. This is the point where you switch your application to use the new target database. The process typically involves:

  1. Stopping the application or putting it into maintenance mode.
  2. Ensuring the AWS DMS task has applied all the final changes from the source.
  3. Updating your application’s connection strings to point to the new target database.
  4. Restarting the application and performing final tests.
  5. Once you’re satisfied, you can stop the DMS task and decommission the old source database.

The AWS Services that Work Alongside DMS

While AWS DMS is a powerful engine for database migration, a truly comprehensive strategy often involves other specialized AWS services. These tools work together with DMS to address specific challenges, from converting database code to moving massive volumes of file data. Think of them as the supporting cast that ensures every part of your migration is handled efficiently.

  • AWS Schema Conversion Tool (SCT): For complex migrations between different database types, known as heterogeneous migrations, the AWS Schema Conversion Tool is an indispensable assistant. When moving from a commercial engine like Oracle to a cloud-native database like Amazon Aurora, the underlying structure and code are not directly compatible. SCT automates the heavy lifting by analyzing your source database’s schema, stored procedures, and functions, and converting them to a format compatible with your target database. It also provides a detailed assessment report that highlights any elements that may require manual adjustment, saving your team hundreds of hours of painstaking work.
  • AWS DataSync: Often, a migration includes more than just databases. You may have large file repositories, document management systems, or network shares that also need to move to the cloud. For these scenarios, AWS DataSync is the ideal tool. It is a managed service designed to automate and accelerate moving large amounts of file-based data between your on-premise storage systems and AWS storage services like Amazon S3 or Amazon EFS. DataSync handles data validation, optimizes network transfer, and provides end-to-end security, simplifying what would otherwise be a complex data transfer project.
  • AWS Snowball: What happens when you have petabytes of data to move? Transferring this amount of information over a standard internet connection could take months or even years, making it completely impractical. For these extreme-scale situations, AWS provides a physical solution with the AWS Snowball family. This service involves shipping a secure, ruggedized storage appliance to your data center. You load your data onto the device, and then ship it back to AWS, where the data is uploaded directly into the AWS cloud at high speed. This method bypasses the public internet, making it a fast, secure, and cost-effective way to migrate enormous datasets.

Partner with the Experts for a Flawless Migration

Migrating a database is a significant undertaking. While AWS DMS and other tools make the process more manageable than ever before, having an experienced partner by your side can make all the difference. A successful migration requires careful planning, technical expertise, and a deep understanding of both your source and target environments.

At Renova Cloud, we specialize in helping businesses navigate their journey to the cloud. As an AWS Migration Competency Partner, we have a proven track record of executing seamless and successful database migrations. Our team of certified experts follows AWS best practices to assess your current setup, design a tailored migration strategy, and manage the entire process from start to finish.

We understand that every business is unique. Whether you are looking to re-host your existing databases, re-platform to a new engine, or re-architect your applications for the cloud, Renova Cloud has the experience to guide you. We help you take full advantage of services like AWS DMS to modernize your data infrastructure with confidence and minimal disruption.

Ready to unlock the power of the cloud for your databases? Contact Renova Cloud today for a free demo and  learn more about our AWS cloud migration services and start planning your successful migration.