Migrating Large Oracle Data Warehouses to Redshift with Limited Bandwidth
A company is migrating a 10 TB Oracle Data Warehouse to Amazon Redshift. The source database runs on premises with limited bandwidth (100 Mbps). The migration must complete within 5 days. Which approach is most cost-effective and meets the timeline?
Quick Answer
The correct answer is to use AWS Snowball Edge for the initial full load, then AWS Database Migration Service (DMS) for ongoing changes. This approach works because a 100 Mbps link can only transfer roughly 1 TB per day, meaning a 10 TB Oracle data warehouse would take over 11 days for the full load alone—far exceeding the 5-day window. Snowball Edge bypasses bandwidth constraints by physically shipping the data, completing the initial transfer in days, while DMS handles incremental replication over the limited connection. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of hybrid migration strategies where network speed is the bottleneck; a common trap is choosing direct DMS or SCT, but SCT is only for schema conversion, not data transfer. Remember the memory tip: “Snowball for the haul, DMS for the crawl”—physical transport for the heavy lift, then sync the changes over the wire.
⚠ Common exam trap
The trap here is that candidates often overlook the bandwidth calculation and assume DMS over Direct Connect is always the fastest and most cost-effective, but the question explicitly asks for the most cost-effective solution that meets the timeline, and Snowball Edge avoids the high recurring costs of Direct Connect for a one-time migration.
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
✓
Use AWS Snowball Edge to transfer the initial full load, then AWS DMS for ongoing changes.
The 10 TB dataset over a 100 Mbps link would take approximately 10 days (10 TB * 8 / 100 Mbps / 86400 seconds/day) for a full load, exceeding the 5-day window. AWS Snowball Edge provides a physical, high-bandwidth transfer for the initial full load, bypassing network constraints, and AWS DMS then captures and applies ongoing changes (CDC) to keep the target in sync. This combination is the most cost-effective as it avoids expensive Direct Connect and meets the timeline.
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 AWS DMS over the internet to migrate data.
Why it's wrong here
Bandwidth insufficient for 10 TB in 5 days.
- ✓
Use AWS Snowball Edge to transfer the initial full load, then AWS DMS for ongoing changes.
Why this is correct
Snowball is fast and cost-effective for large data transfer.
- ✗
Use AWS Schema Conversion Tool (SCT) to convert and then upload to S3.
Why it's wrong here
SCT does not handle data transfer.
- ✗
Use AWS DMS with AWS Direct Connect at 1 Gbps.
Why it's wrong here
Direct Connect may not be available immediately; also costly.
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Variation 1. A company is migrating a 10 TB Oracle data warehouse to Amazon Redshift. The migration must minimize data transfer costs and ensure data integrity. Which TWO steps should the company take?
hard- A.Use AWS DMS to replicate data directly over the internet
- B.Use Amazon Kinesis Data Streams to stream data to Redshift
- C.Use Amazon Redshift Spectrum to query data in S3 after loading
- ✓ D.Use AWS Schema Conversion Tool (SCT) to convert the Oracle schema to Redshift
- ✓ E.Use AWS Snowball Edge to physically transfer the data
Why D: The AWS Schema Conversion Tool (SCT) is specifically designed to convert Oracle database schemas to Amazon Redshift-compatible schemas, handling data type mappings, stored procedures, and other schema objects. This step is critical for a successful migration as it ensures the target schema is optimized for Redshift's columnar storage and MPP architecture, reducing manual rework and potential data integrity issues.
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