This content originally appeared on Level Up Coding - Medium and was authored by Hayk Simonyan
Most developers think scaling is complicated. They see “system design” and immediately think they need years of experience or some magical intuition to understand it.
But scaling is just solving problems in order.
You start with one server. It gets slow. You figure out why, then fix it. Rinse and repeat until you’re handling millions of requests.
The problem is nobody teaches you the order. They jump straight to Kubernetes and microservices and all this complex stuff, and you’re sitting there thinking “but I don’t even know why we need more than one server.”
So let me walk you through it. The way it actually works.
Step One: Understanding Your Single Server
Here’s where everyone starts, whether they admit it or not.
One server. Your app, your database, everything sitting on one machine.
For a lot of applications, this is more than fine.
But you need to understand what breaks. Where the limits are.
Because if you can’t articulate the problems with a single server setup, you definitely can’t explain why you need anything more complex.
What happens when traffic spikes? Where’s your bottleneck? Is it CPU? Memory? Disk I/O? Network?
These aren’t theoretical questions. In interviews, this is what separates people who’ve actually built things from people who’ve just memorized blog posts.
I walk through setting up a single server from scratch in the full breakdown below 👇
Your Database Isn’t Just Storage
Most developers treat databases like a black box.
Data goes in. Data comes out. Magic happens in between.
But your database is almost always your bottleneck. It’s where scaling gets real and things get expensive, both in money and complexity.
Can you handle read-heavy loads differently than write-heavy loads? Do you know when to use read replicas? What about connection pooling? Database sharding?
This stuff sounds boring until your app is crawling at 2 seconds per request and you have no idea why.
I’ve seen developers throw more application servers at a problem when the real issue was database queries. More servers just meant more connections hammering an already-overloaded database.
This is where you need to learn about database scaling and how to separate it from the web tier 👇
Vertical vs. Horizontal: The First Real Decision
Okay, your single server is maxed out. You need to scale.
Which direction do you go?
Vertical scaling: bigger server, more RAM, faster CPU.
Horizontal scaling: more servers, distribute the load.
The decision isn’t obvious. It depends on your specific situation, traffic patterns and your budget.
Sometimes vertical is the right answer. Sometimes horizontal. Sometimes both.
Senior engineers know how to think through these tradeoffs. They don’t just pick the trendy option.
You need to learn about the tradeoffs before choosing one 👇
Load Balancing: Where Theory Hits Reality
Everyone talks about load balancers like they’re magic.
Just put one in front of your servers and boom, infinite scale.
Except… which algorithm do you use? Round-robin? Least connections? IP hash? Weighted distribution?
And more importantly: why?
There’s even more, like Layer 4 vs Layer 7 load balancing. Health check intervals. Failover strategies. Connection draining.
These are decisions that affect actual performance in actual systems that handle actual traffic 👇
The Single Point of Failure Problem
Let’s say you’ve done everything right.
Multiple application servers. Database replicas. Load balancer distributing traffic. Everything’s redundant.
Except your load balancer is a single point of failure.
Or your database master. Or your cloud provider’s availability zone.
You didn’t eliminate single points of failure. You just moved them around.
You should walk through an architecture diagram and immediately identify where things will break.
And learn how to actually mitigate them 👇
As you can see, scaling isn’t rocket science.
It’s just understanding problems in the right order. Starting simple and adding complexity only when you need it.
This way you’re making informed tradeoffs.
How to Scale Like a Senior Engineer (Servers, DBs, LBs, SPOFs) was originally published in Level Up Coding on Medium, where people are continuing the conversation by highlighting and responding to this story.
This content originally appeared on Level Up Coding - Medium and was authored by Hayk Simonyan
Hayk Simonyan | Sciencx (2025-10-15T14:09:36+00:00) How to Scale Like a Senior Engineer (Servers, DBs, LBs, SPOFs). Retrieved from https://www.scien.cx/2025/10/15/how-to-scale-like-a-senior-engineer-servers-dbs-lbs-spofs/
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