horizontal vs vertical scaling

*Horizontal vs Vertical Scaling = Scale Out vs Scale Up*

Think of it like handling more customers in a restaurant:

*1. Vertical Scaling = Scale Up*
*What*: Add more power to ONE existing server.
Bigger CPU, more RAM, faster SSD. Go from 4GB RAM → 32GB RAM.

*Example*: Your h ttp://t3.medium EC2 → upgrade to m5.4xlarge

*Pros*: Simple. No code changes. Just reboot with bigger machine.
*Cons*: There’s a limit. AWS maxes out. Single point of failure. Downtime during upgrade.
*Called*: "Scaling Up"

*2. Horizontal Scaling = Scale Out*
*What*: Add MORE servers instead of bigger servers.
Go from 1 server → 5 servers handling same traffic.

*Example*: 1 web server → Load Balancer + 5 web servers. Kubernetes does this automatically.

*Pros*: No limit. If 5 servers aren’t enough, add 10. No downtime. Fault tolerant.
*Cons*: App must support it. Need load balancer, shared DB, session management. More complex.
*Called*: "Scaling Out"

*Quick table*
Vertical Scaling Horizontal Scaling
**Method** Bigger server More servers
**Complexity** Low High
**Limit** Hardware max Almost no limit
**Downtime** Yes, during upgrade No, add/remove live
**Cost** Expensive big machines Pay for what you use
**Cloud term** Resize EC2 instance Auto Scaling Groups, K8s HPA
*Fresher interview answer:*
'Vertical scaling means increasing resources of a single server like CPU and RAM. Horizontal scaling means adding more server instances to distribute load. Cloud-native apps prefer horizontal scaling because it’s elastic and has no single point of failure. Kubernetes Horizontal Pod Autoscaler is a real example of horizontal scaling.'

*DevOps reality*: Modern apps use horizontal + auto-scaling. Vertical is just for quick fixes.

Which one does Kubernetes use by default?

Видео horizontal vs vertical scaling канала VictoryDeveloper