1. Amazon's Lengthy April Outage
Amazon's cloud outage that started April 21 was the grand-daddy of cloud outages for 2011, drawing major attention to the cloud's sometimes fragile state and also showcasing that when the going gets tough, communication is key. In April, Amazon suffered a catastrophic cloud outage that knocked some of its biggest customers offline for several days.
If that wasn't bad enough, the massive cloud vendor remained silent as customers struggled to get back up and running. After nearly a week of not a peep, Amazon released a highly-technical, long-winded manifesto chronicling what happened (Amazon blamed a "re-mirroring storm") and offered customers an apology and a cloud credit. The incident was seen by many as a sort lesson in how not to handle an outage.