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Difficulty: HardDatabase Migration and Schema Conversion using DMS and SCT

A company is planning to migrate an on-premises 15 TB Oracle database to an Amazon Aurora PostgreSQL-Compatible Edition DB cluster. The source database is highly active, generating over 35 GB of redo logs per hour. To minimize downtime, a Solutions Architect is designing a heterogeneous database migration strategy using the AWS Schema Conversion Tool (AWS SCT) and AWS Database Migration Service (AWS DMS) with Change Data Capture (CDC). The migration must minimize CPU overhead on the source database and prevent replication lag during the CDC phase.

Which combination of actions should the Solutions Architect perform to meet these requirements? (Select two.)

  1. Configure the AWS DMS source database endpoint to use the Binary Reader method rather than LogMiner to access the archived and active redo logs directly.Answer
  2. Enable minimal supplemental logging at the database level and table-level supplemental logging for all tables selected for replication on the source Oracle database.Answer
  3. C
    Disable supplemental logging on the source Oracle database to prevent write amplification and minimize CPU utilization during the Change Data Capture (CDC) phase.
  4. D
    Configure the AWS DMS target database endpoint with the useLogminerReader connection attribute to offload log parsing from the source database.
  5. E
    Install the AWS Schema Conversion Tool (AWS SCT) directly on the AWS DMS replication instance to automatically convert and apply schemas in real-time during the CDC phase.

Answer

Configure the AWS DMS source database endpoint to use the Binary Reader method rather than LogMiner to access the archived and active redo logs directly, and enable minimal supplemental logging at the database level and table-level supplemental logging for all tables selected for replication on the source Oracle database.
The correct combination of actions requires configuring the AWS DMS source database endpoint to use the Binary Reader method instead of LogMiner, and enabling minimal supplemental logging at the database level along with table-level supplemental logging for all replicated tables. The Binary Reader method is designed for high-volume Oracle databases (typically generating more than 10-20 GB of redo logs per hour) because it reads the redo logs directly from the file system or ASM, minimizing database CPU overhead. Supplemental logging is a prerequisite for AWS DMS to read change data from Oracle redo logs.

Step-by-Step Solution

1
Analyze database migration scale and constraints.
Identified a heterogeneous migration from a 15 TB Oracle database to Amazon Aurora PostgreSQL-Compatible Edition, with a high write load generating 35 GB/hour of redo logs. The solution must minimize CPU overhead and replication lag.
This establishes that AWS DMS Change Data Capture (CDC) is required alongside AWS SCT for schema conversion, and that standard LogMiner may struggle with high redo log volume.
2
Select the appropriate log reader method for AWS DMS.
Determined that the Binary Reader method should be used on the source endpoint instead of LogMiner.
Binary Reader reads redo and archived logs directly from the OS or ASM, bypassing the database engine for log processing. This mitigates the CPU overhead on the highly active source database and handles high-throughput logs much more efficiently.
3
Configure required logging on the source Oracle database.
Enabled minimal supplemental logging at the database level and supplemental logging at the table level for primary keys/unique keys.
AWS DMS requires supplemental logging on the source Oracle database to populate redo logs with the data needed to reconstruct SQL updates for CDC. Without this, the DMS task cannot perform ongoing replication.

Key Concept

AWS Database Migration Service (DMS) Change Data Capture (CDC) configurations for high-volume Oracle databases.
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Topics

Database Migration and Schema Conversion using DMS and SCT

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