Why choosing the right storage matters in HLD - Architecture Impact

System Overview - Why choosing the right storage matters

This system demonstrates how choosing the right storage affects performance, scalability, and reliability. It shows a typical web application using cache, database, and file storage to handle different data types efficiently.

Architecture Diagram

User
  |
  v
Load Balancer
  |
  v
API Gateway
  |
  v
+-------------------+
|    Application    |
|      Server       |
+-------------------+
  |          |          
  v          v          v
Cache      Database   File Storage
(Redis)   (SQL DB)    (Object Store)

Components

User

client

Sends requests to the system

Load Balancer

load_balancer

Distributes incoming requests evenly to servers

API Gateway

api_gateway

Routes requests to appropriate services and handles security

Application Server

service

Processes business logic and coordinates data access

Cache (Redis)

cache

Stores frequently accessed data for fast retrieval

Database (SQL DB)

database

Stores structured data with strong consistency

File Storage (Object Store)

storage

Stores large unstructured files like images and videos

Request Flow - 12 Hops

User → Load Balancer

Load Balancer → API Gateway

API Gateway → Application Server

Application Server → Cache (Redis)

Cache (Redis) → Application Server

Application Server → Database (SQL DB)

Database (SQL DB) → Application Server

Application Server → File Storage (Object Store)

File Storage (Object Store) → Application Server

Application Server → API Gateway

API Gateway → Load Balancer

Load Balancer → User

Failure Scenario

Component Fails:Database (SQL DB)

Impact:Structured data queries fail; cache may serve stale data; writes are blocked

Mitigation:Use database replication and failover; rely on cache for read availability; queue writes for retry

Architecture Quiz - 3 Questions

Why does the system check the cache before querying the database?

A To avoid using the load balancer

B To store large files efficiently

C To reduce latency by serving frequent data faster

D To handle user authentication

Design Principle

Choosing the right storage type for different data ensures the system is fast, scalable, and reliable. Cache speeds up frequent reads, databases provide consistency for structured data, and file storage handles large files efficiently.