When designing scalable and robust systems, one must consider several things such as data storage, maintainability, and other challenges. Here are my recommendations and ideas for addressing these topics.

Recommendations

• Architecture: Use serverless microservices architecture
• Consistency: Implement weak consistency where appropriate
• Data Storage: If >100K users, implement database sharding & replication
• Scalability: If >1K users, use load balancing and horizontal scaling
• Performance: If >10K users, use CDN and data level caching
• Maintainability: Follow SOLID principles for development
• Availability: Prepare disaster recovery plan
• Security: Follow guidelines such as OWASP and PCI Security Standards
• Quality: Implement continuous integration, testing, and deployment

Challenges

• Complexity
  • Complex application impacts development speed and maintenance costs
  • Implementing a microservices architecture can effectively manage this complexity
• Traffic
  • High traffic can impact performance
  • Load balancing can handle high traffic along with caching and using a CDN
• Availability
  • High availability requires high uptime
  • Include redundancy in system design using load balancers and data partitioning
• Throughput
  • Throughput impacts performance
  • Caching can improve throughput along with asynchronous processing
• Scalability
  • Application needs to be able to scale for increased load
  • Implementing microservices with load balancing improves scalability

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