Right-sizing avoids over- and under-provisioning. Monitor CPU and memory before upgrading. CPU-bound apps need more cores; memory-bound need RAM. Start with modest specs and scale up based on metrics; use vertical scaling first, then horizontal if needed.
Measure first
- CPU: Check utilization and steal time (on VPS). Sustained high usage or steal indicates need for more cores or dedicated CPU.
- Memory: Check used, cached, and swap. Swap usage often means you need more RAM.
- Baseline: Run under normal and peak load; use averages and percentiles (e.g. p95).
CPU vs memory bound
- CPU-bound: Encoding, compilation, heavy computation → add cores or faster CPU.
- Memory-bound: Large datasets, many connections, caches → add RAM.
- I/O-bound: Database, logs → improve disk (SSD, IOPS) or network.
Scaling approach
- Vertical first: Upgrade to a larger instance (more vCPU/RAM) until cost or limits.
- Horizontal: Add more servers and load balance when a single box is not enough.
- Auto-scaling: Use when load is variable; set min/max and scale triggers based on metrics.
Summary
Measure CPU, memory, and I/O; identify bottlenecks. Right-size for the workload: vertical scaling first, then horizontal. Avoid guessing; use metrics and trends.
