Business continuity management

AWS keeps your data and other resources in the data centers in various geographical locations across the globe; these locations are known as regions. Each region has two or more availability zones for high availability and fault tolerance. These availability zones are made up of one or more data centers. All of these data centers are in use and none are kept offline; that is, there aren't any cold data centers. These data centers house all the physical hardware resources such as servers, storage, and networking devices, and so on, that are required to keep all the AWS services up and running as per the service level agreement provided by AWS. All AWS core applications such as compute, storage, databases, networking are deployed in an N+1 configuration, so that, in the event of a data center failure due to natural calamity, human error or any other unforeseen circumstance, there is sufficient capacity to load-balance traffic to the remaining sites. 

Each availability zone is designed as an independent failure zone so that the impact of failure is minimum and failure can be contained by other availability zone(s) in that region. They are physically separated within a geographical location and are situated in the lower risk flood plains. 

Depending on the nature of your business, regulatory compliance, performance requirements, disaster recovery, fault tolerance, and so on, you might decide to design your applications to be distributed across multiple regions so that they are available even if a region is unavailable.

The following figure demonstrates typical regions with their availability zones: