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Bigpipe is a kind of custom technology to accelerate page rendering using a pipelining logic. The general idea is to decompose web pages into small chunks called pagelets and pipeline them through several execution stages inside web servers and browsers, so eventually it helps increasing performance and speed.
Haystack is a kind of caching solution for Facebook photos posted by users that developed by Facebook which is originally designed to serve the long tail of requests seen by sharing photos in a large social network. The key feature of Haystack is to avoid disk operations when accessing meta-data.
- Haystack provides a fault-tolerant and simple solution to photo storage at dramatically less cost and higher throughput than a traditional approach using NAS appliances.
Reference
http://blog-bhaskaruni.blogspot.com/2012/12/facebook-architecture.html