Horizontal vs Vertical Scaling
· 2 min read
Horizontal scaling and vertical scaling are two strategies for increasing the capacity and performance of your application or infrastructure:
Horizontal Scaling (Scaling Out)
- Definition: Adding more machines or instances to your system.
- How: You deploy additional servers (e.g., more VMs, containers, or physical machines) to distribute the load.
- Benefits:
- Increases fault tolerance and availability.
- Easier to scale dynamically (especially in cloud environments).
- No single point of failure.
- Example: Adding more web servers behind a load balancer.
Vertical Scaling (Scaling Up)
- Definition: Increasing the resources (CPU, RAM, storage) of an existing machine.
- How: You upgrade the hardware or allocate more resources to your current server.
- Benefits:
- Simple to implement (just upgrade the server).
- No need to change application logic for distribution.
- Limitations:
- There is a hardware limit to how much you can scale up.
- If the server fails, the whole application may go down.
- Example: Upgrading a server from 8GB RAM to 32GB RAM.
Summary Table
| Scaling Type | Method | Pros | Cons |
|---|---|---|---|
| Horizontal | Add more servers/instances | High availability, scalable | More complex, needs load balancing |
| Vertical | Add more resources to server | Simple, no code changes | Hardware limits, single point of failure |
In practice:
- Modern cloud-native applications often use horizontal scaling for better resilience and flexibility.
- Vertical scaling is useful for quick upgrades or legacy systems.