Wednesday, July 25, 2012

Part 1: (AZ Series) What is AWS Availability Zone ?

Amazon Web Services (AWS) currently serves hundreds of thousands of customers in more than 190 countries. AWS is steadily expanding their global infrastructure to help customers achieve lower latency and higher throughput, and to ensure that customer data resides only in the Region they specify. AWS currently operates at 8 regions around the world and they are constantly expanding their infrastructure as I write this article. Following diagram illustrates their current regional infrastructure distribution:

Each Amazon EC2 Region is designed to be completely isolated from the other Amazon EC2 Regions. This infrastructure design achieves the greatest possible failure independence and stability. Also by launching EC2 instances in separate Amazon Regions, we can design our application to be closer to specific customers or to meet legal/compliance or other requirements. 
Every Amazon Region is further sub divided into Availability Zones. By launching EC2 instances in separate Availability Zones (AZ), we can protect our applications from the failure of a single location.

So what is an Amazon Availability Zone?

Amazon operates state-of-the-art, highly available data center facilities. However, failures can occur that affect the availability of EC2 instances that are in the same location. Although this is rare, if you host all your Amazon EC2 instances in a single location that is affected by such a failure, your instances will be unavailable.
So to overcome this every Amazon Region is further sub divided into Availability zones. Amazon Availability Zones are distinct physical locations having Low latency network connectivity between them inside the same region and are engineered to be insulated from failures from other AZ’s. Each availability zone runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable; they have Independent power, cooling, network and security. Common points of failures like generators and cooling equipment are not shared across Availability Zones. Additionally, they are physically separate; such that even extremely uncommon disasters such as fires, tornados or flooding would only affect a single Availability Zone. The following diagram illustrates availability zone concept: (image Source : AWS)

We can visualize each AZ internally having Single Data Center or Multiple Data centers. The following diagram illustrates the current AZ allocation of AWS infrastructure:(image Source : AWS)

  • ·         Region :US-EAST( North Virginia) has 5 availability zones
  • ·         Region :US-West (California + Oregon) has 6 availability zones
  • ·         Region :Europe – West (Dublin) has 3 availability zones
  • ·         Region :Asia Pacific (Japan) has 2 availability zones
  • ·         Region :Asia Pacific (Singapore) has 2 availability zones
  • ·         Region :South America (Sao Paulo) has 2 availability zones
  • ·         Region : Gov Cloud

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