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HLDsystem_design~12 mins

Why load balancers distribute traffic in HLD - Architecture Impact

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System Overview - Why load balancers distribute traffic

This system explains why load balancers distribute incoming user traffic across multiple servers. The goal is to ensure no single server is overwhelmed, improving system reliability, speed, and availability.

Architecture Diagram
User
  |
  v
Load Balancer
  |
  +---------+---------+
  |         |         |
Server 1  Server 2  Server 3
  |         |         |
Database  Database  Database
Components
User
client
Sends requests to the system
Load Balancer
load_balancer
Distributes incoming requests evenly across servers to prevent overload
Server 1
service
Processes user requests
Server 2
service
Processes user requests
Server 3
service
Processes user requests
Database
database
Stores and retrieves data for servers
Request Flow - 6 Hops
User → Load Balancer
Load Balancer → Server 2
Server 2 → Database
Database → Server 2
Server 2 → Load Balancer
Load Balancer → User
Failure Scenario
Component Fails:Load Balancer
Impact:All incoming user requests fail because traffic cannot be distributed to servers
Mitigation:Use multiple load balancers with failover or clustering to avoid single point of failure
Architecture Quiz - 3 Questions
Test your understanding
Why does the load balancer send requests to different servers?
ATo confuse the servers
BTo make the user wait longer
CTo prevent any single server from getting too much traffic
DTo reduce the number of users
Design Principle
Load balancers improve system reliability and performance by spreading user requests evenly across multiple servers, preventing overload and enabling scalability.