System design and scalability

Scalability

• Horizontal vs vertical scaling

  • Vertical scaling means increasing the resources of a specific node. It's easier than horizontal scaling but it's limited by memory or disk space.

  • Horizontal scaling means increasing the number of nodes.

• Load balancer

• Database denormalization and NOSQL

• Database partitioning (sharding)

• Caching

• Asynchronous processing & queues

• Network metrics

  • 1.Bandwidth: The maximum amount of data that can be transfer (bits/gigabytes per second)

  • 2.Throughput: The actual amount of data that is transferred

  • 3.Latency: The delay between the sender sending the sending information and the receiver receiving it

  • 增加傳送道的寬度: Bandwidth, Throughput增加, 但Latency不變

  • 縮短傳送道: Bandwidth, Throughput不變, 但Latency減少

  • 加速: Bandwidth, Throughput增加, Latency減少

• MapReduce

Considerations

• Failures

• Availability

• Reliability

• Read-heavy: cache

• Write-heavy: queuing up the writes

• Security