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Difficulty: MediumDatabase Migration and Schema Conversion using DMS and SCT

A company is planning to migrate an on-premises Oracle database to an Amazon Aurora PostgreSQL DB cluster. A solutions architect uses the AWS Schema Conversion Tool (SCT) to convert the database schema and configures an AWS Database Migration Service (DMS) replication task using the Full Load and ongoing replication (CDC) option. The Full Load phase completes successfully, but the DMS replication task transitions to a failed state shortly after the Change Data Capture (CDC) phase starts. Which of the following is the most likely cause of this failure?

  1. The source Oracle database was not configured with supplemental logging enabled, preventing AWS DMS from reading the change data from the redo logs.Answer
  2. B
    The target Amazon Aurora PostgreSQL DB cluster was not configured with binary logging (binlog) enabled, which is required for AWS DMS to write ongoing changes during the CDC phase.
  3. C
    The migration path was incorrectly classified as replatforming instead of refactoring in the AWS Schema Conversion Tool (SCT), causing the DMS task to fail during schema constraint validation.
  4. D
    The target Amazon Aurora PostgreSQL DB cluster's secondary reader instance was not configured with Multi-AZ replication enabled, causing the CDC phase to fail when trying to synchronize read traffic.

Answer

The source Oracle database was not configured with supplemental logging enabled, preventing AWS DMS from reading the change data from the redo logs.
The correct answer is correct because AWS DMS CDC tasks require supplemental logging to be enabled on the source Oracle database. This allows DMS to capture the full row changes from the Oracle redo logs. If supplemental logging is not enabled, the DMS task will fail to replicate ongoing changes after the full load completes.

Step-by-Step Solution

1
Analyze the migration scenario and tools used.
The migration is heterogeneous (Oracle to Aurora PostgreSQL) using SCT for schema conversion and DMS for data replication.
Understanding the source, target, and tools is the first step in identifying migration configuration requirements.
2
Identify the phase where the failure occurs.
The Full Load phase succeeded, but the Change Data Capture (CDC) phase failed immediately after starting.
Since the Full Load succeeded, connectivity and basic write permissions to the target are functioning, meaning the failure is specific to the CDC configuration.
3
Evaluate the source database configuration requirements for DMS CDC.
For Oracle source databases, AWS DMS requires supplemental logging to be enabled to read ongoing changes from the redo logs.
Without supplemental logging, the redo logs do not contain the complete column information needed by DMS to reconstruct changes, leading to task failure.

Key Concept

Enabling source database logging mechanisms (such as supplemental logging for Oracle or binary logging for MySQL) is a mandatory prerequisite for AWS DMS Change Data Capture (CDC) tasks.
Estimated Time:2m 0s
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Topics

Database Migration and Schema Conversion using DMS and SCT

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