3 Steps for Minimal Downtime MySQL Migration to Amazon RDS Using AWS DMS
A company is planning to migrate a 1 TB MySQL database from on-premises to Amazon RDS for MySQL. The migration must have minimal downtime and support ongoing replication. Which THREE steps should the company include in the migration plan? (Choose THREE.)
Quick Answer
The answer is to use AWS DMS with ongoing replication from the on-premises MySQL database, which enables a near-zero downtime cutover by continuously syncing changes while the source remains live. This works because AWS DMS captures ongoing changes from the MySQL binary logs (binlog) and applies them to the target Amazon RDS instance, allowing you to stop the source application only after the target is fully caught up. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of the full migration lifecycle, specifically the need for a stable, low-latency network connection—such as AWS Direct Connect or a VPN—to maintain replication integrity and avoid data loss during the final cutover window. A common trap is assuming a one-time full load is sufficient, but the question explicitly demands minimal downtime and ongoing replication, which only CDC (Change Data Capture) via DMS provides. Memory tip: think “DMS + binlog + Direct Connect” as the three pillars of a zero-downtime MySQL migration.
⚠ Common exam trap
Many exam-takers assume an EC2 proxy is needed for DMS replication, but DMS replication instances handle connectivity directly, and the proxy is only used in specific scenarios like VPC peering across regions or complex network topologies.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set up an AWS Direct Connect or VPN connection between on-premises and AWS.
A stable, low-latency network connection (Direct Connect or VPN) is essential for AWS DMS to perform ongoing replication with minimal downtime. Without this, the replication can be interrupted by network issues, causing data loss or extended cutover windows.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set up an AWS Direct Connect or VPN connection between on-premises and AWS.
Why this is correct
Network connectivity is required for DMS to access the source.
- ✗
Deploy an Amazon EC2 instance to act as a proxy for the DMS replication.
Why it's wrong here
DMS can connect directly to the source; a proxy is unnecessary.
- ✓
Create the target Amazon RDS for MySQL instance.
Why this is correct
The target database must be provisioned before migration.
- ✓
Use AWS DMS with ongoing replication from the on-premises MySQL database.
Why this is correct
Ongoing replication minimizes downtime by capturing changes.
- ✗
Install the AWS Schema Conversion Tool on the source server to convert the schema.
Why it's wrong here
Schema conversion is not needed since the target is also MySQL.
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Same concept, more angles
3 more ways this is tested on DBS-C01
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Variation 1. A company is migrating a 500 GB MySQL database from on-premises to Amazon RDS for MySQL. The migration must have minimal downtime and support ongoing replication. Which AWS service should be used?
medium- A.Use mysqldump to export the database and import to RDS during a maintenance window.
- B.Use AWS Schema Conversion Tool (SCT) to convert the schema and migrate data.
- C.Take a physical backup, copy it to Amazon S3, and restore to RDS.
- ✓ D.Use AWS Database Migration Service (DMS) with a full load and ongoing replication from a change data capture source.
Why D: AWS DMS is the correct choice because it supports both a full load of the 500 GB database and ongoing replication using change data capture (CDC) from the on-premises MySQL source. This enables minimal downtime by keeping the target RDS instance synchronized during the migration window, and it handles schema conversion automatically for MySQL-to-MySQL migrations without needing a separate tool.
Variation 2. A company is migrating a 2 TB MySQL database from on-premises to Amazon RDS for MySQL. They need to minimize downtime and ensure data consistency. They plan to use AWS DMS. What is the first step they should take before starting the migration task?
easy- A.Create a read replica of the source database to reduce load.
- ✓ B.Enable binary logging (binlog) on the source MySQL database.
- C.Disable foreign key checks on the source database to speed up the load.
- D.Enable binary logging on the target RDS for MySQL instance.
Why B: AWS DMS requires binary logging (binlog) to be enabled on the source MySQL database to capture ongoing changes during the full-load and change data capture (CDC) phase. This ensures data consistency and minimizes downtime by allowing DMS to replicate incremental changes after the initial load. Without binlog, DMS cannot perform CDC, and the migration would be limited to a one-time snapshot, risking data loss or extended downtime.
Variation 3. A company is migrating a 500 GB MySQL database from on-premises to Amazon RDS for MySQL. The database is critical and must have minimal downtime. Which approach should be used to migrate the database with the least downtime?
medium- ✓ A.Use AWS Database Migration Service (DMS) with a replication instance to perform a full load and then ongoing replication until cutover.
- B.Modify the on-premises database to use a new master user and then use the AWS Schema Conversion Tool to migrate.
- C.Create a read replica of the on-premises database and promote it to a standalone RDS instance.
- D.Export the database using mysqldump and import into RDS using mysql command-line tool. Schedule a maintenance window for cutover.
Why A: AWS DMS with ongoing replication (change data capture) is the correct approach because it performs an initial full load of the 500 GB database and then continuously replicates incremental changes from the source to the target RDS instance. This allows the source database to remain operational during migration, and the cutover can be performed in seconds by stopping application writes and applying the final changes, minimizing downtime to near zero.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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