How to Minimize Downtime When Migrating to AWS RDS Using DMS and SCT
A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. They need to minimize downtime. Which TWO actions should they take?
Quick Answer
The answer is to use AWS SCT to validate and convert the schema before migration and to set up AWS DMS with ongoing replication. These two actions work together to minimize downtime because SCT ensures the target Oracle RDS schema is compatible and optimized ahead of time, eliminating last-minute conversion errors, while DMS’s ongoing replication captures and applies continuous changes from the source database during the cutover, allowing you to switch traffic in seconds rather than hours. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of the “minimize downtime” requirement by distinguishing between pre-migration preparation and real-time data synchronization; a common trap is choosing a single-AZ deployment or disabling archiving, but archiving is essential for Change Data Capture (CDC) to keep replication running. Remember the memory tip: “SCT for structure, DMS for data flow”—validate first, then replicate live to keep downtime low.
⚠ Common exam trap
Candidates often think disabling archivelog mode speeds up data transfer (Option E), but in reality, CDC requires archivelogs to capture ongoing changes, and disabling them would force a full stop-and-copy migration, increasing downtime.
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 AWS DMS with change data capture (CDC) from the source
AWS DMS with change data capture (CDC) enables continuous replication of ongoing changes from the source Oracle database to the target RDS instance. This allows the source to remain fully operational during the bulk load phase and then switch over with minimal downtime, as only the final CDC catch-up is needed before cutover.
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 AWS DMS with change data capture (CDC) from the source
Why this is correct
CDC enables near-zero downtime migration.
- ✗
Increase the allocated storage on the target RDS instance to improve performance
Why it's wrong here
Storage size does not affect downtime.
- ✓
Use AWS SCT to validate and convert the schema before migration
Why this is correct
Schema validation reduces compatibility issues during migration.
- ✗
Deploy the target RDS instance as a Single-AZ to simplify replication
Why it's wrong here
Single-AZ does not reduce downtime; Multi-AZ is recommended for production.
- ✗
Disable Oracle archivelog mode to speed up data transfer
Why it's wrong here
Archiving is required for CDC; disabling it would prevent ongoing replication.
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Same concept, more angles
4 more ways this is tested on DBS-C01
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Variation 1. A company is migrating a 500 GB SQL Server database to Amazon RDS for SQL Server. They need to minimize downtime and support ongoing changes during migration. Which approach should they take?
medium- A.Use native SQL Server backup and restore to RDS
- B.Set up a Direct Connect connection and use log shipping
- C.Use SQL Server Integration Services (SSIS) to replicate data
- ✓ D.Use AWS DMS with full load and change data capture (CDC)
Why D: AWS DMS with full load and change data capture (CDC) is the correct approach because it allows the initial 500 GB data load to be migrated while continuously replicating ongoing changes from the source SQL Server database to Amazon RDS for SQL Server. This minimizes downtime by enabling a cutover only after the target is fully synchronized, and it supports ongoing changes during migration without requiring the source database to be taken offline.
Variation 2. A company is migrating a 500 GB SQL Server database to Amazon RDS for SQL Server. They need to minimize downtime. Which TWO actions should they take? (Choose two.)
medium- A.Store database backup files in Amazon S3
- B.Use AWS Schema Conversion Tool to convert the schema
- ✓ C.Use AWS DMS with ongoing change data capture (CDC)
- ✓ D.Set up AWS Direct Connect for the migration
- E.After migration, enable Multi-AZ for high availability
Why C: AWS DMS with ongoing change data capture (CDC) minimizes downtime by performing a full load of the 500 GB database and then continuously replicating ongoing changes from the source SQL Server to the target Amazon RDS for SQL Server. This keeps the target nearly synchronized, so the final cutover can be completed in seconds or minutes. Setting up AWS Direct Connect provides a dedicated, high-bandwidth network connection between the on-premises environment and AWS, which reduces latency and increases transfer speed for the initial load and ongoing replication, further minimizing downtime. Together, these two actions effectively reduce overall downtime during the migration.
Variation 3. A company is migrating a 1 TB SQL Server database to Amazon RDS for SQL Server. They need to minimize downtime and support ongoing replication. Which combination of AWS services should they use?
medium- ✓ A.AWS SCT and AWS DMS
- B.AWS S3 and AWS Glue
- C.AWS DMS alone
- D.Native SQL Server backup and restore to RDS
Why A: AWS DMS (Database Migration Service) can perform a full load of the 1 TB SQL Server database and then continuously replicate ongoing changes using change data capture (CDC) to minimize downtime. AWS SCT (Schema Conversion Tool) is used to assess and convert any incompatible schema objects (e.g., stored procedures, indexes) from the source SQL Server to the target RDS for SQL Server, ensuring a smooth migration. Together, they provide a complete solution for heterogeneous or homogeneous migration with minimal downtime and ongoing replication.
Variation 4. A company is migrating a 200 GB Oracle database to Amazon RDS for Oracle. Which TWO steps should be taken to ensure a successful migration? (Choose two.)
medium- A.Enable TDE encryption on the source database before migration.
- B.Use AWS DMS only for heterogeneous migrations; use Oracle Data Pump instead.
- ✓ C.Use AWS DMS with full load and ongoing replication.
- D.Export the database using expdp and import using impdp.
- ✓ E.Use AWS Schema Conversion Tool (SCT) to assess and convert the schema.
Why C: AWS DMS supports both homogeneous and heterogeneous migrations, and for a 200 GB Oracle database, using full load plus ongoing replication minimizes downtime by continuously applying changes from the source to the target RDS instance. This approach is ideal for migrating large databases with minimal disruption.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DBS-C01 exam.