Amazon OA 面试真题解析：设计简单 S3 对象存储服务

S3 is a publicly accessible HTTP service.

It supports PUT of a key (URL) that stores a value.

It supports GET that retrieves the value.

The goals of S3 are scale, durability, availability, and latency in that priority order.

Access control, APIs other than PUT and GET, and geographic distribution are out of scope.

Do you have questions about the requirements?

这道题本质上是一个简化版的对象存储设计题，核心是围绕 key-value 存储来回答如何支持 PUT 写入和 GET 读取，并在“可扩展性、持久性、可用性、延迟”的优先级约束下做架构取舍。面试时通常会从数据分片、复制、故障恢复和读写路径入手，说明如何把对象按 key 路由到合适的存储节点，并通过多副本或其他冗余机制保证数据不丢失，同时兼顾高可用和低延迟。由于题目明确排除了访问控制、除 PUT/GET 之外的 API 和跨地域分布，所以重点不在复杂业务功能，而在存储系统的基本一致性、分布式存储和容错设计。