The correct answer is to increase the instance class of the DMS replication instance. This resolves the AWS DMS insufficient memory error during Oracle to Aurora migration because the replication instance’s memory is used to cache transactional changes during ongoing replication (CDC). When the volume of cached changes exceeds that memory, DMS fails; a larger instance class provides more memory to handle the cache, allowing the migration to complete without disruption. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of DMS resource sizing under real-world constraints—specifically, that insufficient memory is a scaling issue, not a configuration or network problem. A common trap is to assume you need to reduce the batch size or pause replication, but the direct fix is vertical scaling. Memory tip: think “CDC cache = RAM need”; if DMS runs out of memory, you need a bigger instance, not a smaller workload.
SAP-C02 Practice Question: Accelerate Workload Migration and Modernization
This SAP-C02 practice question tests your understanding of accelerate workload migration and modernization. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 a 10 TB Oracle database to Amazon Aurora PostgreSQL. The database is business-critical and must have minimal downtime. The company has set up AWS DMS with ongoing replication from the source. During the migration, the company notices that DMS is failing with an error indicating insufficient memory. What should the company do to resolve this issue and complete the migration?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the instance class of the DMS replication instance
AWS DMS replication instances have finite memory allocated to cache changes during ongoing replication (CDC). When the volume of cached changes exceeds the instance's memory, DMS fails with an insufficient memory error. Increasing the instance class of the DMS replication instance (Option B) provides more memory to handle the cache, resolving the error without disrupting the migration.
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.
✗
Increase the memory on the source Oracle database
Why it's wrong here
The error is on the DMS replication instance, not the source database.
✓
Increase the instance class of the DMS replication instance
Why this is correct
DMS replication instance memory is insufficient; upgrading the instance class resolves the issue.
Related concept
Read the scenario before looking for a memorised answer.
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Change the DMS task to use change data capture (CDC) only and skip the full load
Why it's wrong here
CDC only will not migrate existing data; a full load is needed.
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Split the migration into multiple smaller tasks
Why it's wrong here
Splitting would require starting over and may increase total downtime.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think the error is on the source database (Option A) or that splitting tasks (Option D) solves memory issues, but DMS's memory error is specific to the replication instance's capacity, not the source or task granularity.
Detailed technical explanation
How to think about this question
DMS uses a memory-based cache (the 'cache change processing' area) to store ongoing changes from the source during CDC. The default cache size is 50% of the replication instance's memory. When the cache fills, DMS writes to disk (swap), which severely degrades performance and can cause failures. Increasing the instance class directly increases the available memory, allowing the cache to grow and avoid disk spillover. In real-world scenarios, a 10 TB database with high transaction volume often requires a dms.c5.4xlarge or larger instance to sustain CDC without memory errors.
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.
Accelerate Workload Migration and Modernization — This question tests Accelerate Workload Migration and Modernization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the instance class of the DMS replication instance — AWS DMS replication instances have finite memory allocated to cache changes during ongoing replication (CDC). When the volume of cached changes exceeds the instance's memory, DMS fails with an insufficient memory error. Increasing the instance class of the DMS replication instance (Option B) provides more memory to handle the cache, resolving the error without disrupting the migration.
What should I do if I get this SAP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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