Managed RDS vs self-managed DB on EC2

WHAT THIS TESTS Whether you can articulate the operational, availability, and security value a managed database provides versus the control and cost of running it yourself.

A GOOD ANSWER COVERS Running PostgreSQL on a bare EC2 instance means your team owns every operational responsibility: installing and patching the database and operating system, configuring and testing backups, setting up replication and failover, monitoring, scaling storage, and handling disk-full or crash recovery at 3 a.m. A managed service like RDS automates most of this. It handles automated backups with point-in-time recovery, applies security and minor-version patches in maintenance windows, and offers Multi-AZ deployments that synchronously replicate to a standby and fail over automatically on instance failure, giving high availability without you building it. On security, RDS provides encryption at rest and in transit, integration with IAM and secrets management, and network isolation, reducing the surface you must secure yourself. The net argument is that a small team should spend its limited engineering time on product, not on undifferentiated database operations.

COMMON WRONG ANSWERS Focusing only on instance cost while ignoring the engineering hours and reliability risk of self-managing, or assuming RDS removes all responsibility (you still tune, size, and secure access).

LIKELY FOLLOW-UPS When self-managing is justified (extreme cost scale, unsupported extensions, deep tuning needs); RDS limitations like superuser access; cost comparison at scale.

ONE CONCRETE EXAMPLE A five-person startup chooses RDS Multi-AZ. When the primary instance hardware fails one night, RDS automatically promotes the standby in about a minute with no engineer paged and no data loss, and nightly automated backups enable point-in-time recovery. Achieving the same on EC2 would require building and maintaining replication, failover automation, and backup tooling the team has no time for.