AWS Availability Zones (AZs): High-Level Overview

This post will provide a high-level overview of AWS Availability Zones, also called as AZ.  Availability Zone is another important concept to understand to have solid AWS fundamentals about AWS Global Infrastructure. 

• AWS has data centers worldwide in multiple locations to help provide high availability and low latency services. These locations are divided into Regions and Availability Zones.
• Every AWS Region is divided into multiple isolated locations known as Availability Zones.
• Availability Zone is essentially an AWS Data Center with its own power supply, low-latency, and high bandwidth network setup.
• An Availability Zone (AZ) is a discrete data center with redundant power, networking, and connectivity in an AWS Region.
• Each Availability Zone has its own power supply and on-site backup generator. And, they are connected via different grids from independent utilities to avoid a single point of failure for any power outage.
• Typically, there are three Availability Zones in a Region. However,  in some cases, there are more than 3. For example, N. Virginia Region has 6 Availability Zones.
• All AZs in an AWS Region are interconnected with high-bandwidth, low-latency networking between AZs.
• Availability Zones are separated in an AWS Region.
• Availability Zones are located away from the city and are in lower-risk flood areas to avoid the flood or any other damage to the data centers.
• AZ’s are physically separated by a meaningful distance, many kilometers, from any other AZ.
• Availability Zones have codes as well, like Region. Availability Zone code has Region Code + a letter added in the end. For example. N. Virginia region has region code us-east-1. And this region has 6 Availability Zones with their code as us-east-1a, us-east-1b, and the rest AZs are coded in the same way.
• AWS customers focused on high availability can design their applications to run on multiple AZs to achieve even greater fault tolerance.
• AZs allow customers to operate production applications and databases that are more highly available, fault-tolerant, and scalable than would be possible from a single data center.
• AZs make partitioning applications for high availability easy. If an application is partitioned across AZs, the application is better isolated and protected from power outages, tornadoes, earthquakes, etc.
• To provide redundancy, AWS allows replication of resources and data in multiple Availability Zones. This helps avoid data loss and provides high availability to the deployed applications. However, these replications don’t happen across regions unless organizations explicitly decide to do so.
• All traffic between AZs is encrypted. Therefore, the network performance is sufficient to accomplish synchronous replication between AZs.
• AWS Regions are separate, and they are not connected with the AWS private network, unlike AWS Availability Zones, which are connected.