Database Migration to RDS with Minimal Downtime
A data engineer needs to migrate an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB and has a continuous stream of write operations. The migration should minimize downtime. Which AWS service should be used?
⚠ Common exam trap
Candidates often choose AWS DataSync (Option A) because they confuse it with a database migration tool, but DataSync cannot replicate live transactional changes and is meant for file or object storage, not relational databases with ongoing writes.
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
✓
AWS Database Migration Service (DMS)
AWS Database Migration Service (DMS) is the correct choice because it supports ongoing replication (change data capture) from an on-premises PostgreSQL source to Amazon RDS for PostgreSQL, enabling a near-zero downtime migration. DMS can handle the 2 TB dataset and continuous write stream by performing a full load followed by continuous replication of changes until the cutover. Other services lack the ability to perform live, transactional replication with minimal interruption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS DataSync
Why it's wrong here
AWS DataSync transfers files and objects between storage systems; it cannot replicate PostgreSQL write-ahead log changes into RDS. It is tempting because DataSync does migrate on-premises data to AWS, and would be correct for moving large file shares or S3 datasets rather than a live relational database.
- ✓
AWS Database Migration Service (DMS)
Why this is correct
AWS Database Migration Service performs continuous replication from the on-premises PostgreSQL source to Amazon RDS for PostgreSQL while the source stays live, then cuts over during a brief window. This satisfies the requirement to minimise downtime for a 2 TB database with ongoing writes.
- ✗
AWS Snowball Edge
Why it's wrong here
AWS Snowball Edge ships data physically, so the continuous write stream would diverge during transit and require a lengthy final sync. It is tempting because Snowball Edge suits multi-terabyte transfers over slow links, and would be correct for bulk offline migration where the source is static.
- ✗
AWS Glue
Why it's wrong here
AWS Glue performs ETL and cataloguing, not continuous replication of a live PostgreSQL source into RDS. It is tempting because Glue does move data between stores, and would be correct for transforming or cataloguing datasets, not for minimising cutover downtime during an active database migration.
Go deeper
Related to this question
About these practice questions
Courseiva writes every DEA-C01 question from scratch — 1,321 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on DEA-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 data engineer is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB in size. The engineer needs to minimize downtime. Which AWS service should be used for the migration?
easy- A.AWS Data Pipeline
- ✓ B.AWS Database Migration Service (DMS)
- C.AWS Snowball
- D.Amazon S3
Why B: AWS Database Migration Service (DMS) is the correct choice because it supports continuous replication (change data capture) from an on-premises PostgreSQL source to Amazon RDS for PostgreSQL, enabling near-zero downtime migration. DMS can handle a 2 TB database by using a large replication instance and tuning task settings, and it automatically converts the source schema to the target RDS engine.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-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 DEA-C01 exam.