When migrating companies from legacy environments to the cloud, invariably you run into older hierarchical, flat file, VSAM, ISAM and other legacy data stores. There are many advantages to moving these databases into a relational database structure. The most important which is that most cloud providers run on relational database models. AWS, for example, supports Oracle, SQL Server, and MySQL. The top three 'other reasons' for moving to a relational database are:
1. Data Access – Thousands of database access tools from query creation to business intelligence.
2. Management and monitoring – Hundreds of tools for management and monitoring of the database.
3. Leverage all the free tools from relational database vendors. Free Oracle database tools include:
-Application Express – WYSIWIG browse based application development and deployment.
-SQL Developer – SQL and PL/SQL development. Database object maintenance.

What is interesting is that Big Data NoSQL databases and XML databases are taking us back to the days of VSAM (key value databases) with NoSQL and IMS (hierarchical) with XML databases?