A power outage at an Amazon Web Services data center in northern Virginia last night knocked some customers offline. Among the sites affected were Heroku, Pinterest, Quora and HootSuite, along with a host of smaller sites. Amazon confirmed the power outage on its Service Health Dashboard, but did not offer details on the root cause of the power outage.
The outage affected only one availability zone, the US-East-1 Region. The downtime led to the usual Twitter trash-talking about how major sites should spread their infrastructure across multiple Amazon availability zones, rather than relying on a single zone. Heroku indicated that its recovery efforts included shifting workloads to other availability zones.
But the outage was the third significant downtime in the last 14 months for the US-East-1 region, which is Amazon's oldest availability zone and resides in a data center in Ashburn, Virginia. The US-East-1 region had a major outage in April 2011 and another less serious incident in March. Amazon's U.S East region also was hit by a series of four outages in a single week in 2010.
While Amazon has multiple avalability zones, IP address research by Huan Li suggests that the majority of Amazon Web Services customers are concentrated in the US East region. Li estimates that Amazon has 5,030 racks in northern Virginia, or about 70 percent of the estimated total of 7,100 racks for AWS. By contrast, Li estimates that the newer Amazon US West (Oregon) region has just 41 racks, which are reportedly deployed in containers.