Caches que usa Facebook sobre PHP: memcached

Interesante artículo: http://cacm.acm.org/blogs/blog-cacm/51564-extreme-agility-at-facebook/fulltext

Facebook’s architecture is based on typical hierarchical PHP Web application model with a layer of data caching and extracted services components.  The caching layer is done via the stable and fast memcached open source software on top of one of the largest installation of MySQL .  The caching layer is so critical to Facebook’s success that Facebook is now one of the main contributors to memcached .