AWS Relational Database Service (RDS) provides managed database administration at a premium price. Under heavy transaction scale, database instance costs can become the largest item on your cloud bill. Deciding when to migrate off managed databases requires evaluating operational margins against engineering risks.
The Managed Database Premium
Managed database services charge a premium (typically 30% to 50% above baseline EC2 costs) for automated backups, minor version patches, and regional replica setup. For databases under 2 Terabytes, this overhead is usually justified by the developer time it saves.
When Migration Makes Sense
We recommend self-hosting database instances on bare EC2 when data volumes exceed 10 Terabytes, query throughput is constrained by provisioned IOPS limits, and you employ a full-time database administrator (DBA). In these cases, moving databases to local NVMe storage can reduce compute costs by over 40% while improving read/write speed.
When You Absolutely Should Not Migrate
If your team lacks dedicated infrastructure support, migrating off RDS is a major risk. Automated backups, replica failover routing, and point-in-time recovery are difficult to self-host reliably. A single production recovery failure will wipe out years of compute cost savings.