What are the 5 criteria for system design?

When designing a system, five key criteria guide the architecture and ensure the system meets its performance and operational goals. Here are the fundamental criteria:

1. Scalability

A system must be designed to handle an increasing number of users, transactions, or data without a significant drop in performance. Scalability involves:

Horizontal scaling (adding more machines) and vertical scaling (increasing resources on existing machines).
Efficient database design to accommodate growing data.

2. Reliability

Reliability ensures that the system operates correctly even in case of failures or unexpected conditions. This includes:

Redundancy: Having backup systems or data to prevent downtime.
Fault tolerance: The ability to continue operating smoothly after a component failure.

3. Performance

A system should have low latency (fast response time) and high throughput (the ability to handle large amounts of requests). Key factors affecting performance include:

Caching: Reducing database queries by storing frequently accessed data in memory.
Load balancing: Distributing traffic across multiple servers to optimize resource use.

4. Availability

Availability refers to the system’s uptime and its ability to provide service even in the event of failures. This includes:

Failover mechanisms: Ensuring the system can switch to backup systems when the primary system fails.
Replication: Running multiple instances of the same service to maintain uptime.

5. Security

Security is critical to protect data and system integrity. Key security principles include:

Encryption: Securing data both in transit and at rest.
Authentication and authorization: Verifying user identity and controlling access to system resources.