The correct choice is AWS Database Migration Service (DMS) with ongoing replication, also known as change data capture (CDC). This approach is essential for migrating a 2 TB PostgreSQL database with a high write workload to Amazon RDS with minimal downtime because DMS first performs a full load of the existing data, then continuously captures and applies incremental changes from the source to the target. This keeps the target RDS instance synchronized right up to the cutover moment, allowing you to switch applications with only a brief pause. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of CDC as the key differentiator for minimizing downtime in large, write-heavy migrations. A common trap is selecting a one-time snapshot or backup restore, which would cause significant data loss or extended downtime. Remember the memory tip: “CDC keeps the clock ticking” — it’s the ongoing replication that makes the cutover nearly seamless.
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB in size and has a high write workload. The company needs to minimize downtime during the migration. Which AWS service or feature should the company use to achieve this?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use AWS Database Migration Service (AWS DMS) with ongoing replication.
AWS DMS with ongoing replication (change data capture, CDC) is the correct choice because it allows continuous synchronization of the source PostgreSQL database with the target RDS for PostgreSQL instance after an initial full load. This minimizes downtime by enabling the target to stay up-to-date with changes until the cutover, which is critical for a 2 TB database with a high write workload.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 pg_dump and pg_restore to export and import the database.
Why it's wrong here
pg_dump/pg_restore requires the source database to be read-only during the dump, causing downtime.
✓
Use AWS Database Migration Service (AWS DMS) with ongoing replication.
Why this is correct
AWS DMS supports ongoing replication via change data capture, minimizing downtime.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the AWS Schema Conversion Tool (AWS SCT) to convert the schema and migrate data.
Why it's wrong here
AWS SCT is primarily for schema conversion, not for minimizing downtime during data migration.
✗
Use AWS DataSync to replicate the database files.
Why it's wrong here
AWS DataSync is designed for file-based data transfers, not for live database migration with minimal downtime.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse AWS DMS with AWS SCT, assuming SCT is needed for same-engine migrations, but SCT is only required for heterogeneous migrations, not for PostgreSQL to RDS PostgreSQL.
Detailed technical explanation
How to think about this question
AWS DMS uses logical replication slots in PostgreSQL to capture changes from the source's write-ahead log (WAL) via the pgoutput plugin, enabling near-real-time CDC. For a 2 TB database, the initial full load can take hours, but ongoing replication keeps the target synchronized with minimal lag, allowing a brief cutover window of seconds to minutes. A common real-world scenario is migrating a high-traffic e-commerce database where even minutes of downtime can cause revenue loss, making DMS with CDC the preferred approach.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Deployment and Migration — This question tests Deployment and Migration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use AWS Database Migration Service (AWS DMS) with ongoing replication. — AWS DMS with ongoing replication (change data capture, CDC) is the correct choice because it allows continuous synchronization of the source PostgreSQL database with the target RDS for PostgreSQL instance after an initial full load. This minimizes downtime by enabling the target to stay up-to-date with changes until the cutover, which is critical for a 2 TB database with a high write workload.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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 an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB in size and has a high write volume. The migration window is limited to 4 hours. Which migration approach provides the fastest initial load with minimal downtime?
medium
A.Use pg_dump to export the database and pg_restore to import into RDS.
B.Create a read replica of the on-premises database and promote it to a standalone database in RDS.
C.Use AWS Schema Conversion Tool (AWS SCT) to convert the schema and then use AWS DMS for ongoing replication.
✓ D.Use AWS DMS with PostgreSQL as source and target, using native logical replication for full load and ongoing replication.
Why D: Option B is correct because AWS DMS can perform a full load using native PostgreSQL logical replication, which is faster than AWS SCT alone (which only converts schema) and faster than using pg_dump/pg_restore for a 2 TB database within 4 hours. Option A is wrong because SCT does not migrate data. Option C is wrong because traditional backup/restore requires downtime for the entire duration. Option D is wrong because read replicas are not applicable for cross-engine migration.
Variation 2. A company is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB and has a sustained write rate of 150 MB/s. The migration must have minimal downtime. Which AWS service or tool should be used for the initial data load and ongoing replication?
medium
✓ A.Use AWS Database Migration Service (AWS DMS) with full load and ongoing replication
B.Use pg_dump and pg_restore
C.Use AWS Schema Conversion Tool (AWS SCT) to convert schema and AWS DMS for data migration
D.Use AWS S3 Transfer Acceleration to upload data to Amazon S3, then restore to RDS
Why A: AWS DMS supports ongoing replication from on-premises to RDS with minimal downtime. Option A is incorrect because pg_dump/pg_restore cannot perform ongoing replication. Option B is incorrect because S3 is for storage, not database replication. Option D is incorrect because the Schema Conversion Tool does not handle data migration.
Variation 3. A company is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB in size and has a sustained write rate of 50 MB/s. The migration must have minimal downtime. Which migration approach should be used?
medium
A.Create an RDS read replica from the on-premises database
B.Use pg_dump and pg_restore
C.Use AWS DMS with a full-load task only
✓ D.Use AWS DMS with ongoing replication (change data capture)
Why D: Option D is correct because AWS Database Migration Service (DMS) with ongoing replication allows minimal downtime by continuously replicating changes from the source to the target. Option A is wrong because AWS DMS with full load only does not support ongoing replication, leading to downtime. Option B is wrong because pg_dump/pg_restore is a logical backup tool that requires downtime during the dump and restore process. Option C is wrong because an RDS read replica can only be created from an existing RDS instance, not from on-premises.
Variation 4. A company is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB and the migration must have minimal downtime. Which TWO AWS services should be used together to accomplish this?
medium
A.AWS CloudFormation
B.AWS DataSync
✓ C.AWS Schema Conversion Tool (AWS SCT)
D.AWS CloudEndure Migration
✓ E.AWS Database Migration Service (AWS DMS)
Why C: AWS DMS provides data migration with ongoing replication, and AWS SCT can help convert schema if needed, but for homogeneous migration, DMS alone is sufficient. However, the question asks for two services; the combination of DMS and SCT is commonly used for heterogeneous migrations. For homogeneous, DMS alone is enough, but SCT can still be used to assess schema compatibility. Option E is incorrect because CloudEndure is for server migration.
Last reviewed: Jun 11, 2026
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