Review “Upgrading from a previous version” for steps common to all database migrations.
Run sp_iqcheckdb to check the validity of your current databases. Repair any index and allocation problems. See “Verify your databases”.
Shutdown your 12.x servers. See “Shut down your 12.x server”.
Run iqunload with the appropriate parameters to migrate your databases. See “Migrate your simplex database”.
Start the migrated database in read-only mode. Update the appropriate configuration settings and database options. See “Start the 15.2 migrated database”.
Use sp_iqcheckdb to verify the migrated database. See“Verify the migrated databases”.
Complete any necessary post-migration tasks. See “Postmigration tasks”.