What this choice changes
The choice changes contention, networking and failure boundaries. Separation is useful only when the operational benefit justifies another host, credential path and recovery procedure.
Compare the decision factors
| Factor | API and database on one VPS | Separate app and database VPS |
|---|---|---|
| Request path | Local connection avoids an inter-host network hop. | Every query depends on the network route and its authentication. |
| Resource contention | API, workers and database share CPU, RAM and disk activity. | Each host has a separate resource budget. |
| Failure boundary | One host event can affect application and database together. | An app-host failure need not stop the database, but the service still needs both. |
| Access scope | One administrator boundary can reach both components. | Database administration can use a narrower host and network boundary. |
| Connection planning | Local pools still need limits across API and workers. | Pools need limits plus network timeout and retry decisions. |
| Recovery | One rebuild must reconstruct both roles and their compatible versions. | Each restore and the application-to-database connection must be rehearsed together. |
When each option earns its place
Keep a small stack combined while measured overlap fits with reserve and one maintenance boundary is acceptable. Separate the database when its resource, access or recovery requirements have become independently important.