Wikia hosts around a 100 000 wikis using the open source Mediawiki software. In this talk I'll take a tour through the process of taking a legacy source code and turning it into a globally distributed system. Wikia runs across 6 datacenters in US and Europe, with half of them being CDN nodes and half being full datacenters. Traffic is directed to closest node depending on traffic situation. In a case of degradation the system turns into a read-only mode. The multiple level of redundancy and distribution contributed to a 99.995% availability to end users.
Specific issues involve:
30th September to 1st October 2010