Minimize Downtime with AWS DMS Ongoing Replication to Aurora
A financial services company is migrating a 500 GB Oracle database to Amazon Aurora MySQL-Compatible Edition. The migration must have minimal downtime and support bidirectional replication for a test-and-cutover approach. The company currently uses Oracle GoldenGate for replication. Which migration strategy should be used?
Quick Answer
The correct choice is to use AWS DMS with a full load and ongoing replication from Oracle to Aurora MySQL, then cut over. This strategy minimizes downtime migration using AWS DMS with ongoing replication because it continuously captures and applies changes from the source Oracle database to the target Aurora MySQL instance, allowing you to test the target environment thoroughly before a brief cutover window. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding that AWS DMS supports heterogeneous migrations with change data capture (CDC), making it ideal for a test-and-cutover approach, while a common trap is assuming you need Oracle GoldenGate or the Schema Conversion Tool for replication—neither handles ongoing data movement in this context. Remember the key distinction: DMS handles the data flow, SCT handles the schema, and GoldenGate is a separate tool not integrated with DMS. A useful memory tip is "DMS for data, SCT for schema, GoldenGate for gold—but not together."
⚠ Common exam trap
Many exam-takers assume Oracle GoldenGate, which the company already uses, must be part of the migration strategy, but AWS DMS can directly handle the replication without GoldenGate, and GoldenGate does not support Aurora MySQL as a target.
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
✓
Use AWS DMS with a full load and ongoing replication from Oracle to Aurora MySQL, then cut over.
AWS DMS with full load and ongoing replication is the correct strategy because it supports minimal-downtime migration from Oracle to Aurora MySQL and can handle bidirectional replication for a test-and-cutover approach. DMS uses change data capture (CDC) from Oracle's redo logs to keep the target in sync, allowing you to validate the target before cutting over. This meets the requirement for minimal downtime and a test-and-cutover workflow without relying on Oracle GoldenGate.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use AWS DMS with a full load and ongoing replication from Oracle to Aurora MySQL, then cut over.
Why this is correct
DMS supports ongoing replication for cross-engine migrations, enabling minimal downtime and test-and-cutover.
- ✗
Use AWS Schema Conversion Tool (SCT) to convert the schema and then use AWS DMS for a one-time full load.
Why it's wrong here
SCT converts schema but does not replicate ongoing changes; DMS full load does not support bidirectional replication.
- ✗
Use AWS DMS with Oracle GoldenGate as a source for continuous replication to Aurora MySQL.
Why it's wrong here
AWS DMS cannot use Oracle GoldenGate as a source; it uses its own CDC mechanism.
- ✗
Use Oracle GoldenGate to replicate directly to Aurora MySQL, then cut over.
Why it's wrong here
GoldenGate does not support Aurora MySQL as a target natively; it requires additional configuration.
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Same concept, more angles
5 more ways this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is migrating a 5 TB Oracle database to Amazon Aurora PostgreSQL. The database has a 4-hour maintenance window weekly. Which migration approach minimizes downtime?
medium- A.Use Oracle Data Pump to export and pg_restore to import.
- ✓ B.Use AWS Database Migration Service (DMS) with change data capture (CDC).
- C.Use AWS Schema Conversion Tool (SCT) to convert schema and then copy data.
- D.Use AWS DMS full load only and then manually sync.
Why B: AWS DMS with CDC allows you to perform an initial full load of the 5 TB database and then continuously replicate ongoing changes from the source Oracle database to the target Aurora PostgreSQL. This minimizes downtime because you can keep the source database fully operational during the migration and only perform a brief cutover to switch applications to the new database, well within the 4-hour maintenance window.
Variation 2. A company is migrating a 5 TB PostgreSQL database to Amazon Aurora PostgreSQL. The database has complex stored procedures and triggers. The migration must be completed within a 30-minute downtime window. Which approach would meet the requirement?
hard- A.Use Database Migration Service (DMS) with validation only.
- ✓ B.Use AWS DMS with full load and ongoing replication, then perform a cutover.
- C.Use AWS SCT to convert the schema and then use pg_dump/pg_restore.
- D.Set up an Aurora read replica from the source PostgreSQL.
Why B: AWS DMS with full load and ongoing replication allows you to migrate the 5 TB database with minimal downtime by continuously replicating changes from the source PostgreSQL to the target Aurora PostgreSQL. When you are ready, you perform a cutover, which typically takes only a few minutes, meeting the 30-minute downtime window. The complex stored procedures and triggers are handled because DMS supports ongoing replication for PostgreSQL, capturing DML and DDL changes.
Variation 3. A company is migrating a 3 TB PostgreSQL database from on-premises to Amazon Aurora PostgreSQL. They need to minimize downtime and ensure that the migration is completed within a maintenance window. Which approach should they use?
medium- ✓ A.Use AWS DMS with full load and ongoing replication (CDC)
- B.Use AWS SCT to convert the schema and then migrate data
- C.Use pg_dump to export the database and pg_restore to import into Aurora
- D.Take a file system snapshot and restore to Aurora
Why A: AWS DMS with full load and ongoing replication (CDC) is the correct approach because it allows you to perform an initial full load of the 3 TB database while continuously capturing changes from the source PostgreSQL using logical replication (via the pglogical extension or native slot-based replication). This minimizes downtime by keeping the target Aurora PostgreSQL nearly synchronized, and you can switch over during a maintenance window with only a brief outage to apply any final lag.
Variation 4. A company is migrating a 500 GB PostgreSQL database from on-premises to Amazon Aurora PostgreSQL. The migration must have a recovery point objective (RPO) of less than 5 minutes and a recovery time objective (RTO) of less than 30 minutes. Which migration strategy should the company use?
hard- A.Create a read replica of the on-premises database and promote it.
- ✓ B.Use AWS DMS with full load and ongoing replication.
- C.Take a full backup using pg_basebackup and restore to Aurora.
- D.Use pg_dump to export the database and import into Aurora.
Why B: AWS DMS with full load and ongoing replication is the correct strategy because it supports continuous change data capture (CDC) from the on-premises PostgreSQL source to Amazon Aurora PostgreSQL, enabling an RPO of less than 5 minutes. The full load phase migrates the initial 500 GB, and ongoing replication keeps the target synchronized with minimal lag, while Aurora’s automated failover and fast recovery help achieve an RTO under 30 minutes.
Variation 5. A company is moving a self-hosted MySQL database to Amazon Aurora MySQL. The current database uses InnoDB with full-text indexes and triggers. The migration must be done with zero downtime. Which approach meets these requirements?
hard- ✓ A.Use AWS DMS with ongoing replication from the source MySQL database
- B.Use mysqldump to export the database and import into Aurora
- C.Set up MySQL replication from on-premises to Aurora using native binlog replication
- D.Export data to Amazon S3 and use Aurora's LOAD DATA FROM S3 command
Why A: AWS DMS with ongoing replication (change data capture) allows continuous synchronization from the source MySQL database to Amazon Aurora MySQL, enabling a zero-downtime migration. DMS captures incremental changes from the source's binary logs (binlog) and applies them to the target, so the database remains fully operational during the migration. This approach also supports InnoDB tables, full-text indexes, and triggers, as DMS handles schema and data replication for these features. Option C (native MySQL binlog replication) is supported by Aurora MySQL, but it requires an initial seed of data which introduces downtime because the source database typically needs to be in a read-only state for a consistent backup. In contrast, DMS with CDC avoids any initial downtime.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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