Migrating RDS not in VPC (EC2 classic platform) to VPC

Hello,

As pointed out in your own link provided: Using the following alternatives, you can move a DB instance not in a VPC into a VPC with minimal downtime. These alternatives cause minimum disruption to the source DB instance and allow it to serve user traffic during the migration. However, the time required to migrate to a VPC will vary based on the database size and the live workload characteristics.

Alternatives:

AWS Database Migration Service (AWS DMS) – AWS DMS enables the live migration of data while keeping the source DB instance fully operational, but it replicates only a limited set of DDL statements. AWS DMS doesn't propagate items such as indexes, users, privileges, stored procedures, and other database changes not directly related to table data. In addition, AWS DMS doesn't automatically use RDS snapshots for the initial DB instance creation, which can increase migration time. For more information, see AWS Database Migration Service.

DB snapshot restore or point-in-time recovery – You can move a DB instance to a VPC by restoring a snapshot of the DB instance or by restoring a DB instance to a point in time. For more information, see Restoring from a DB snapshot and Restoring a DB instance to a specified time.

I would recommend reaching out to your assigned TAM/SA to plan for the maintenance. They will provide you the necessary resources and also make sure that you get minimal downtime by suggesting you the best way forward.