[AWS] AWS Database Migration Service (DMS)

AWS DMS is a data migration service that migrates on-premise databases to AWS or databases within AWS.

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Database Migration Service (DMS)

The AWS DMS can migrate your data to and from the most widely used commercial and open-source databases.

• The source database remains fully operational during the migration, minimizing downtime to applications that rely on the database.

• DMS Supports homogeneous and heterogeneous migration
  • Homogeneous migrations such as Oracle to Oracle or MySQL to MySQL
  • Heterogeneous migrations between different database platforms, such as Oracle or Microsoft SQL Server to Amazon Aurora.

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Common Use Cases

• Migration
  • On-premise data to AWS
  • Cloud-to-cloud Migration
  • Change the data type or database engines (Heterogeneous migrations)
• Replication
  • Multi-cloud copies
  • DB to Data Lake or Data warehouse
• Consolidation
  • Reduce the data size just for core information
  • Cost Reduction

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Working with DMS

Replication Instances

A replication instance is a specialized compute resource.

• It does:
  • Initial load
    • Full load
  • Ongoing replication (update) of changes
    • Change data capture (CDC)
  • Monitoring changes and publishing logs

Sources

• Endpoint identifier
• Source engine
• Database engine and connection details
• Optional Configuration
  • KMS
  • Tags

Targets

• Endpoint identifier
• Target engine
• Optional Configuration
  • KMS
  • Tags

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Replication Task

A replication task is a migration job running on the replication instance.

Task Configuration

• Task identifier
• Replication instance
• Source and Target
• Migration type
  • Migrate existing data
    • one-time migration
  • Migrate existing data and Replicate ongoing changes
    • initial + continuous replication
  • Replicate data changes only
    • replication of new changes only

Task Settings

• Target table preparation

Option	Existing tables	Non-existing tables	Existing Data
Do nothing	No change	Create	No change
Drop tables	Drop and create	Create	clear
Truncate	No change	Create	clear

• LOB (Large Object such as Blob) column handling
  • Do not include
    • ignore LOB columns
  • Full LOB
    • include all LOB data
  • Limited LOB
    • truncate LOB data to the defined max size (the default is 64KB)

Other Configurations

• Validation
• Logging
  • CloudWatch logs
• Table mappings
  • Schema
  • Include/Exclude tables

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