DEA-C01 Data Ingestion and Transformation Practice Question
A company uses Amazon RDS for MySQL as a source for AWS DMS to replicate data to S3. The replication task is failing with 'OutOfMemory' errors on the DMS instance. The source table has 10 million rows with large BLOB columns. Which THREE changes would most likely resolve the issue?
⚠ Common exam trap
Many candidates assume Full LOB mode is always the safest choice for large objects, but it actually increases memory usage and can cause OutOfMemory errors, whereas Limited LOB mode with a max size is the correct memory-saving approach.
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 the LOB column settings to 'Limited LOB mode' and specify a max LOB size.
Setting LOB columns to 'Limited LOB mode' with a specified max LOB size prevents DMS from loading entire LOBs into memory. Instead, DMS truncates LOBs to the specified size, reducing memory consumption and avoiding OutOfMemory errors when replicating large BLOB columns from MySQL to S3.
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 the LOB column settings to 'Limited LOB mode' and specify a max LOB size.
Why this is correct
Limited LOB mode avoids loading entire LOBs into memory.
- ✗
Disable logging for the DMS task to free memory.
Why it's wrong here
Logging uses minimal memory; disabling it does not resolve OOM.
- ✗
Enable Full LOB mode to handle LOBs more efficiently.
Why it's wrong here
Full LOB mode loads entire LOBs into memory, worsening the issue.
- ✓
Increase the DMS replication instance size to a compute-optimized class.
Why this is correct
More memory prevents OOM errors.
- ✓
Increase the number of parallel threads in the task settings.
Why this is correct
More threads can process smaller batches, reducing per-thread memory usage.
Visual reference
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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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.