The Amazon EC2 and S3 services suffered some problems in the summer of 2011. A
configuration error during an upgrade in the East Coast facility triggered a cascade that
delayed all services in the facility. Internet services including Foursquare and Reddit that
used the facility were impacted by the problems for almost a week [Tibken 2011]. Amazon
engineers learned a lot from the problems and the same issue is unlikely to occur again
[http://aws.amazon.com/message/65648/]. But, the outage points out the risks involved in
any centralized system. Ironically, the main problems were caused by algorithms designed
to copy data to multiple servers to reduce risks. On the other hand, with multiple facilities,
Amazon provides the ability to spread content and risk across multiple locations.