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Database Migration

Database Migration Service (DMS)

AWS Database Migration Service (AWS DMS) is a cloud service that makes it easy to migrate relational databases, data warehouses, NoSQL databases, and other types of data stores. You can use AWS DMS to migrate your data into the AWS Cloud or between combinations of cloud and on-premises setups.

  • Managed Database Migration Service
  • Runs using a replication instance
  • Source and Destination Endpoints point at ..
    • Source and Target Databases
  • One Endpoint must be on AWS
  • Migraiton Types:
    • Full Load - one off migration of all data
    • Full Load + CDC (change data capture) - also captures ongoing changes in the source DB
    • CDC Only - copy existing data using other native tooling and only apply data changes
  • Does not support schema conversion but ...
    • tool available called Schema Conversion Tool(SCT)
    • assist with Schema Conversion

Schema Conversion Tool (SCT)

  • SCT is used when converting one database engine to another
    • .. including DB -> s3
    • on-premises MSSQL -> RDS MySQL
    • on-premises ORACLE -> Aurora
  • SCT is not used when migrating between DB's of the same type
    • .. On-premise MySQL -> RDS MySQL
  • Works with database types like
    • OLTP DB Types - MySQL, Oracle, MSSQL
    • OLAP - Teradata, Oracle, Vertica, Greenplum

DMS & Snowball

  • Larger migrations might be multi-TB in size
    • moving data over takes time and consumes capacity
  • DMS can utilise snowball..
  • Steps: 1. Use SCT to extract data locally and move to a snowball device (generic fie format) 2. Ship the device back to AWS.They load onto an S3 bucket. 3. DMS migrates from S3 into the target store 4. CDC can capture data changes -> s3 (intermediary) -> write to target DB