Examkin

Question

Difficulty: MediumDatabase Migration and Schema Conversion using DMS and SCT

A solutions architect is migrating an on-premises Oracle database to an Amazon Aurora PostgreSQL-Compatible Edition DB cluster using AWS Database Migration Service (AWS DMS) and the AWS Schema Conversion Tool (AWS SCT). The solutions architect successfully converts the schema, creates the target tables, and configures an AWS DMS task with full load and Change Data Capture (CDC) enabled. The full load phase completes successfully, but the replication task immediately fails and stalls upon transitioning to the CDC phase. Which two actions should the solutions architect take to resolve this issue and resume replication? (Select two.)

  1. Enable minimal supplemental logging at the database level and add supplemental logging for primary keys on all tables selected for replication on the source Oracle database.Answer
  2. Configure the source Oracle database in ARCHIVELOG mode and ensure that archived redo logs are retained on the source server for a sufficient duration, such as at least 24 hours.Answer
  3. C
    Enable logical replication on the target Aurora PostgreSQL DB cluster by setting the rds.logical_replication parameter to 1 in the DB parameter group.
  4. D
    Install and configure the AWS Schema Conversion Tool (AWS SCT) agent on an EC2 instance in the same VPC as the replication instance to capture transactions from the Oracle database log writer (LGWR).
  5. E
    Create a new AWS DMS task with the replication type set to replicate data changes only, and configure the task to start from the current Oracle System Change Number (SCN) without enabling supplemental logging on the source.

Answer

Enable minimal supplemental logging at the database level and add supplemental logging for primary keys on all tables selected for replication on the source Oracle database, and configure the source Oracle database in ARCHIVELOG mode and ensure archived redo logs are retained on the source server for a sufficient duration.
The correct configurations involve setting the source Oracle database to ARCHIVELOG mode, retaining the archived redo logs for at least 24 hours, and enabling minimal supplemental logging at the database level along with primary key supplemental logging on the replicated tables. These steps ensure that the Oracle database writes the changed data values to its transaction logs and keeps them available for AWS DMS to read during the CDC phase.

Step-by-Step Solution

1
Analyze the failure mode of the AWS DMS CDC task.
The task successfully completes the full load phase but fails immediately upon starting the CDC phase, which suggests a failure to read source transaction logs.
DMS CDC for Oracle source relies on reading redo logs and archived logs. If they are not configured correctly, the task fails immediately when transitioning to replication.
2
Verify Oracle source database logging configuration.
Supplemental logging is missing or not enabled for the primary keys of the tables, and the database must be in ARCHIVELOG mode.
Without supplemental logging, Oracle does not write the necessary columns to the redo logs for DMS to reconstruct the changes.
3
Identify the correct logging configurations required for the migration.
Enable minimal supplemental logging, enable supplemental logging for primary keys, configure ARCHIVELOG mode, and retain archived redo logs.
These steps ensure that transaction log details are preserved and accessible by AWS DMS for ongoing replication.

Key Concept

Replication log requirements for AWS DMS CDC from an Oracle source
Rate this question

Topics

Database Migration and Schema Conversion using DMS and SCT

More questions from this topic