The reason for the outage was a series of problems involving an automated system designed to verify configuration values in the cache and replace invalid values with updated values from the persistent store. An error sent system into a feedback loop that only cutting traffic to a database cluster and rebooting the site could solve.
The social network has apologized for the downtime and is reportedly working to prevent future problems in the area. However, with a user-base of over 500 million, this outage is bound to have its repercussions. As InformationWeek notes: “As a comparison, a service disruption last year at another major Internet property, Google, resulted in a 5% drop in Internet traffic.”
But there is also a bright side to this unfortunate event. As today's best tweet says: "Facebook is down. Worker productivity rises. U.S. climbs out of recession". Or another one: "Facebook is down. Expect a huge spike in births in nine months."