What is AWS Availability Zones (AZ) ?

What is AWS Availability Zones (AZ) ?

An Availability Zone (AZ) is a separate location inside an AWS Region that is designed to be isolated from other AZs' failures. There are currently 100 Availability Zone (AZs) spread over 33 regions, according to AWS documentation (as of April 3rd, 2024). An Availability Zone (AZ) is defined as one or more district data centers located within an AWS region. 

Every Availability Zone (AZ) has its own networking, cooling, power, and connectivity systems. In order to minimize correlated failures, AZs are also substantially separated from one another up to 60 miles (~100 km), yet close enough to allow for synchronous replication with single-digit millisecond latency.

AWS Availability Zones (AZ)
Fig 1.1- AWS Availability Zones (AZ)

As a result, the isolation helps in protecting applications from interruptions caused on by occurrences like as power outages and hardware malfunctions. The following points can be used to sum up the advantages of Availability Zone (AZs):
  • High performance:  When performing maintenance on resources in one Availability Zone (AZ), such as patching or upgrades, you can seamlessly shift traffic to resources in another zone. This eliminates downtime for your applications.
  • Scalability:  Availability Zone (AZs) allow you to easily scale your deployments up or down. By distributing resources across multiple zones, you can handle increased traffic or workload demands without bottlenecks.
  • Fault Tolerance:  By spreading your resources across zones, you create a more fault-tolerant architecture. If one Availability Zone (AZ) encounters an issue, the impact is minimized as other zones can take over the workload.
  • Data ResidencyAvailability Zone (AZs) within a region are geographically bound. This can be beneficial for applications with data sovereignty or compliance requirements that restrict data storage to a specific geographic location.
  • High Availability: This is the primary advantage. Availability Zone (AZs) are geographically separate data centers within a single AWS Region. Each zone has independent power, cooling, and networking. If a hardware failure or natural disaster disrupts one AZ, your resources in another zone can remain operational, minimizing downtime for your applications.
Every Availability Zone (AZ) in an AWS Region is connected to every other Availability Zone (AZ) by fully redundant, dedicated metro fiber, providing high-bandwidth, low-latency networking.