Planning is key to successful migration. Before you upgrade to a new version of Informix, review the Migration Guide
to ensure that you understand the migration process, prerequisites, and reversion options. The "Preparing for Migration" section of the guide contains information about how to prepare your database server environment for migration.
After you migrate to the new version, you should also take time to plan for using the features included in the new server version. The "Completing required post-migration tasks" section of the Migration Guide
contains information on the post-migration tasks you should complete to prepare the new version of the server for use. You should also view the lists of new and changed configuration parameters, new environment variables, new keywords of SQL, and new system databases that are in the Migration Guide.
For information on migrating to Version 11.70, see the IBM Informix Migration Guide