Should I resize one VPS or add more VPS instances?
Vertical scaling changes one instance’s capacity. Horizontal scaling adds instances and requires the application to distribute work and handle shared state correctly. The better choice depends on the bottleneck and architecture, not simply the number of users.
Instructions
1. Identify what limits the current service
Measure CPU, memory, database contention, storage and request latency. A single larger instance may be appropriate for a workload that cannot safely split across machines, but it still has a single-instance failure boundary.
2. Check horizontal-scaling readiness
Identify session storage, uploaded files, databases, scheduled jobs, queues and outbound actions. Additional instances must not duplicate exclusive tasks or create inconsistent data. Decide how traffic is balanced and how unhealthy instances are removed.
3. Test the chosen change with a rollback path
For a resize, verify provider downtime and guest resource activation. For additional instances, validate identity, configuration and data access in isolation before introducing traffic. Compare application-level results and operational complexity after the change.
Check the result
- The scaling approach addresses the measured bottleneck.
- State, jobs and traffic routing remain correct during normal operation and a planned failure test.
Troubleshooting
- Adding instances creates duplicate jobs
- Separate singleton or coordinated tasks from ordinary request workers.
- A larger instance does not improve response time
- Revisit the bottleneck; a shared database or external dependency may still dominate.
Official references
Use the documentation for your installed version when a flag, service name or platform feature differs.