This Page describes a series of Steps in a General Approach to Data Migration between Source Systems and Target Systems.
It covers Extract, Transformation and Load.
Here's a Simple Approach to Migration.

There are no technical risks in Data Migration because it is a well-established procedure.
However, it is important to get User involvement right from the start, and
to get User sign-off at the end when all the Data has been successfully migrated.

• Setting-up the Data Migration Process ...
  1. Choose a Data Modelling Tool with Reverse Engineering Capability,(such as ERWin).
  2. Define and create the Data Dictionary.
  3. Identify all the required Data Sources, and an 'owner' for each Source.
     • Data Feeds
     • Legacy Systems
     • Operational Data Stores
  4. If your Sources include Access Databases, then check out MDB Tools, from Brian Burns.
  5. Define the Data Items required, in consultation with the Users.
  6. Create the Data Models for the Source Data.
  7. Define Data Validation Checks (bottom-up) and Clean-Up Business Rules for Source Data.
  8. Carry out an Audit of the Data Quality in major Databases, (bottom-up and top-down).
     Evaluate the benefits of a Data Cleansing Product, such as Seamless from the C and C Group.
  9. Define the Staging Area, with MIRror Tables to store Extract Files.
  10. Create the Business Data Model for the Consolidated Database
  11. If the final target is an ERP, such as SAP, then create the Data Model for the Target ERP Database
      For SAP, J.D.Edwards, Peoplesoft and Siebel, a Modelling Tool called Saphir, from Silwood Technology
      can be very useful here.
  12. Define the Data Mapping between Source and Target Data Items.
  13. Optionally, create a CRUD Matrix to identify the interactions between Data and Functions.
  14. Define Acceptance Tests for data in the Integrated Database.

• Executing the Data Migration Process.
  1. Optionally, choose a Data Migration Tool.
  2. Create Extract Files for each Data Source in turn.
  3. Resolve any Errors with the Users.
  4. Create Extract and perform Data Clean-Up.
  5. Complete the Migration, (Extract, Transform and Load) for each Data Source.
  6. Run Acceptance Tests on the Integrated Target Database,(esp. Referential Integrity).