AWS DMS for On-Premises MySQL to RDS MySQL Data Sync: Best Practices and Alternative Replication Options

For your MySQL to RDS MySQL data synchronization needs, AWS DMS is indeed a suitable option for ongoing, low-latency replication between on-premises and AWS environments.

1. DMS Suitability: AWS DMS is well-suited for your use case of ongoing data synchronization between on-premises MySQL and RDS MySQL. It supports continuous data replication using Change Data Capture (CDC) and is designed to keep source and target databases in sync with minimal latency. For homogeneous migrations (MySQL to MySQL), DMS offers serverless options that can migrate data, table partitions, data types, and secondary objects like functions and stored procedures.

2. Critical Prerequisites: For reliable CDC with minimal replication lag, ensure your on-premises MySQL has:

• Binary logging enabled
• Binary log format set appropriately (typically ROW format is recommended)
• Sufficient binary log retention period
• A database user with appropriate permissions for AWS DMS to access the binary logs
• Proper network connectivity between your on-premises environment and AWS

3. Common Pitfalls: Some challenges to be aware of:

• DMS has limitations with certain DDL propagation - not all schema changes are automatically replicated
• Large transactions may require special handling
• CDC replication requires more monitoring and complexity than offline options
• Schema changes require ongoing maintenance
• The RPO depends on redo/transaction log generation and network transfer time

4. Alternative Replication Options: Since you're performing a homogeneous migration (MySQL to MySQL), you have several alternatives:

• MySQL binlog replication: Traditional MySQL binary log replication if you're already familiar with it and want more control
• Aurora Read Replica: If your source is compatible, though this is more applicable for RDS MySQL sources
• AWS Storage Gateway or AWS Transfer Family: These could be options depending on your specific requirements

5. Native MySQL Replication: Yes, native MySQL binlog replication can be configured from an on-premises MySQL instance to an RDS MySQL instance. This approach gives you more control over the migration process and provides a familiar migration path if you're already experienced with MySQL replication. The main considerations compared to DMS are:

• You'll need to manage the replication setup and monitoring yourself
• You'll need to handle any replication errors manually
• You may need to deal with network configuration challenges between on-premises and AWS

Both DMS and native MySQL replication can achieve near-zero downtime migration. Your choice should depend on your team's familiarity with MySQL replication, your specific requirements for control over the process, and your preference for managed vs. self-managed solutions.
Sources
Planning your database migration process - Migrating Your Databases to Amazon Aurora
Which aws service i can use to continuesly sync data from onpremises to aws | AWS re:Post
Migrate a self-managed MySQL database to Amazon Aurora MySQL using AWS DMS homogeneous data migrations | AWS Database Blog
Migrate an on-premises MySQL database to Amazon RDS for MySQL - AWS Prescriptive Guidance
AWS DMS - AWS Prescriptive Guidance

This is a great question and one that comes up frequently when teams move from self-managed MySQL workloads to managed RDS MySQL while keeping live data synchronization in place. You are right to evaluate both AWS DMS and native MySQL replication because the best approach depends on your operational goals, tolerance for latency, and how much control you want over the replication process.

1. DMS Suitability and Best Practices

AWS Database Migration Service is a strong choice for ongoing MySQL-to-MySQL synchronization, especially if you need flexibility during cutover or plan to handle schema evolution gracefully. DMS uses Change Data Capture (CDC) via MySQL binary logs, which allows continuous replication with latency often under a few seconds when tuned correctly.

For best performance and reliability, confirm the following on your on-premises source:

Binary Logging: Enabled with binlog_format=ROW. This ensures every row-level change is captured accurately.

Binlog Retention: Long enough to cover potential DMS downtime or network interruptions (for example, 24–48 hours).

Privileges: The DMS replication user must have REPLICATION SLAVE, REPLICATION CLIENT, and SELECT privileges.

Network: Minimize round-trip time between the replication instance and your MySQL host, ideally under 10 ms for ongoing syncs.

Server ID: Ensure a unique server ID for both DMS and the source to prevent conflicts.

The official AWS reference for these settings is in the AWS DMS documentation for MySQL sources : https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source.MySQL.html .

2. Common Operational Pitfalls

A few issues tend to catch teams off guard when using DMS for continuous replication:

Schema Changes: DMS does not automatically propagate DDL operations. Any schema changes on the source must be applied manually or through schema management automation.

Large Transactions: These can cause temporary replication lag, especially if the binary logs grow faster than they can be consumed.

LOB Handling: DMS supports several modes for Large Objects (full, limited, inline). Choosing the right mode has a major impact on latency and throughput.

Monitoring: Enable CloudWatch metrics for replication lag and task health. DMS tasks are resilient but need operational visibility to catch stalls early.

A practical strategy is to schedule routine validation tasks using the DMS data validation feature so you can confirm that target tables remain consistent over time. : https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Tasks.Validation.html

3. Native MySQL Replication as an Alternative

Since this is a homogeneous MySQL-to-MySQL migration, native replication is absolutely a viable alternative. You can set up your on-premises MySQL instance as a source and configure your RDS MySQL instance as a replica. This approach can yield slightly lower latency and leverages built-in MySQL mechanisms.

Here are the main considerations:

You will need to enable binary logging on the source and use the CHANGE MASTER TO command on RDS to point to the on-premises host.

RDS requires the use of publicly accessible endpoints or a VPN/Direct Connect tunnel for replication traffic.

Unlike DMS, schema evolution and error recovery are entirely manual.

Monitoring replication lag and maintaining the replication user are your responsibility.

Detailed steps can be found in Replicating an external MySQL database to Amazon RDS MySQL : https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MySQL.Replication.html .

4. Choosing Between DMS and Native Replication

Here’s how most production teams decide:

Choose DMS if you want a managed, auditable service with data validation, retry handling, and flexible task management. DMS is ideal if your migration is part of a broader modernization plan or if you anticipate transforming schemas or filtering tables.

Choose native replication if your goal is low-latency, straightforward replication between well-controlled MySQL environments where you can manage operational details yourself.

For long-term syncs that might later transition into a cutover event, DMS often provides more flexibility. Once the synchronization is stable, you can repoint application traffic to the RDS target and disable CDC.

5. Field Insights

In practice, I have seen the best results when teams start with DMS for its transparency and monitoring capabilities and then evaluate whether native replication could simplify ongoing operations later. DMS can also coexist with native replication for staged migrations.

Another useful optimization is to place the DMS replication instance in the same subnet or VPC as your RDS target, reducing latency and improving throughput.

Summary

Both DMS and native MySQL replication can meet your requirements. The key difference lies in how much management overhead you are comfortable with and whether you need DDL handling, data validation, and transformation. For most hybrid topologies where the on-premises source must remain active for a period of time, DMS is generally the most robust and maintainable solution.

I can outline an architectural pattern showing how to combine DMS ongoing replication with CloudWatch alerting and automated validation scripts for a near-zero-downtime cutover. It’s a reliable approach that balances observability and operational control.