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Difficulty: HardAssess and Select Migration Strategy (7 Rs)

An enterprise is planning to migrate a legacy retail order management system to AWS. The migration must be completed within 6 months due to an upcoming data center lease expiration. The system consists of three distinct tiers:

* Presentation Tier: A custom Node.js web application running on VM instances. The development team has containerized the application locally and wants to run it on a managed container service (Amazon ECS on AWS Fargate) to reduce operational overhead without modifying any application code.
* Database Tier: An Oracle Database 19c running on IBM AIX. The database has complex PL/SQL packages. The enterprise wants to migrate the database to Amazon Aurora PostgreSQL to eliminate expensive Oracle licensing costs. The schema and code migration will require utilizing the AWS Schema Conversion Tool (AWS SCT) and rewriting database stored procedures.
* Legacy Processing Tier: A proprietary, COBOL-based batch processing engine that runs on a mainframe. The system relies on physical USB security keys connected to the mainframe hardware for cryptographic validation. There is no timeline or budget to refactor this application, and it must remain operational.

Which of the following migration strategy mappings should the solutions architect recommend under the 7 Rs framework? (Select TWO.)

  1. Refactor the Database Tier by using the AWS Schema Conversion Tool (AWS SCT) and AWS Database Migration Service (AWS DMS) to convert the schema and rewrite stored procedures for Amazon Aurora PostgreSQL.Answer
  2. Retain the Legacy Processing Tier on-premises because the mainframe workload depends on physical USB hardware keys that cannot be virtualized or replicated in the cloud.Answer
  3. C
    Replatform the Database Tier by using AWS Schema Conversion Tool (AWS SCT) to migrate the Oracle database schema to Amazon Aurora PostgreSQL without modifying application code.
  4. D
    Rehost the Legacy Processing Tier by using AWS Application Migration Service (MGN) to lift-and-shift the mainframe operating system blocks directly to Amazon EC2.
  5. E
    Rehost the Database Tier by using AWS Database Migration Service (AWS DMS) to perform a direct schema-only lift-and-shift of the Oracle database on IBM AIX to Amazon RDS for PostgreSQL.

Answer

The Solutions Architect should recommend Refactoring the Database Tier to migrate from Oracle to Aurora PostgreSQL, and Retaining the Legacy Processing Tier on-premises due to its physical hardware dependency.
The Database Tier requires a database engine migration from Oracle to Amazon Aurora PostgreSQL, which involves schema conversion and rewriting stored procedures. This falls under the Refactor (Re-architect) migration strategy. The Legacy Processing Tier depends on physical USB hardware keys connected to mainframe hardware and lacks a migration or modernization budget, which requires keeping the workload on-premises. This falls under the Retain migration strategy.

Step-by-Step Solution

1
Analyze the Database Tier requirements and constraints.
The target is to move from Oracle to Aurora PostgreSQL to eliminate licensing costs. This requires schema conversion and rewrite of PL/SQL stored procedures, which represents a structural database change.
Identifying the required modifications helps classify the migration strategy. Since code changes and engine transformation are required, this matches the Refactor (Re-architect) strategy under the 7 Rs framework.
2
Analyze the Legacy Processing Tier requirements and constraints.
The system runs on mainframe hardware, requires a physical USB security key for cryptographic validation, and has no modernization budget or timeline.
Since the physical hardware dependency cannot be replicated in a standard cloud environment and there is no budget to rewrite the system, the workload must remain on-premises, which maps to the Retain strategy.
3
Compare valid strategies with the options to identify correct selections and eliminate distractors.
Refactoring is correct for the database tier, and Retaining is correct for the mainframe. Rehosting or Replatforming options either misclassify the database engine conversion or propose technically impossible cloud migrations for the mainframe.
Selecting the correct two strategies ensures compliance with the 7 Rs framework and the technical realities of the legacy architecture.

Key Concept

Selecting migration strategies under the 7 Rs framework requires evaluating technical dependencies (like physical hardware or operating systems) and the degree of application modification (like database engine conversions).
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Assess and Select Migration Strategy (7 Rs)

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