Resumen
At the foundation of Amazon's cloud computing are infrastructure services such as Amazon's S3 (Simple Storage Service), SimpleDB, and EC2 (Elastic Compute Cloud) that provide the resources for constructing Internet-scale computing platforms and a great variety of applications. Under the covers these services are massive distributed systems that operate on a worldwide scale. This scale creates additional challenges, because when a system processes trillions and trillions of requests, events that normally have a low probability of occurrence are now guaranteed to happen and must be accounted for upfront in the design and architecture of the system. When designing these large-scale systems at Amazon, systems designers use a set of guiding principles and abstractions related to large-scale data replication and focus on the trade-offs between high availability and data consistency. This article presents some of the relevant background that has informed the designers' approach to delivering reliable distributed systems that must operate on a global scale.