5 Things You Need to Know About AWS Regions and Availability Zones

6 min readMar 31, 2020

Anytime you provision infrastructure from Amazon Web Services (AWS), you will need to choose which of the AWS Regions and Availability Zones it will live in. Here are 5 things you need to know about these geographic groupings, including tips on how to choose, and things to watch out for.

1. What are AWS Regions and How Many are There?

AWS Regions are the broadest geographic category that define the physical locations of AWS data centers. Currently, there are 22 regions dispersed worldwide across North America, South America, Europe, China, Africa, Asia Pacific and the Middle East. All Regions are isolated and independent of one another.

Every region consists of multiple, separate Availability Zones within a geographic area. AWS offers Regions with a multiple AZ design — unlike other cloud providers who see a region as one single data center.

AWS has a larger footprint around the globe than all the other cloud providers, and to support their customers and ensure they maintain this global footprint, AWS is constantly opening new Regions.

Here’s a look at the different regions and their AWS code.

**Note: AWS manages US GovCloud, AWS China, and the general AWS as distinct “partitions”. An account must be set up within the partition to get access to any of the regions in that partition.**

2. What are AWS Availability Zones and How Many are There?

An Availability Zone (AZ) consists of one or more data centers at a location within an AWS Region. Each AZ has independent cooling, power, and physical security. Additionally, they are connected through redundant, ultra-low-latency networks.

In AZ’s, customers are able to operate production applications and databases that are more fault tolerant, scalable, and highly available than you would see from a single data center.

Every AZ in an AWS Region is interconnected with high-bandwidth, low-latency networking, fully redundant, metro fiber in order to provide high-throughput, low-latency networking between AZ’s. All AZ’s are physically separated by a significant distance from any other AZ, although all are within 60 miles of each other.

Around the world, there are currently 69 Availability Zones. Here’s a breakdown of each Availability Zones you can find within a Region.

There is also an option available called AWS Local Zones. This allows deployment of latency-sensitive portions of applications close to large populations where no AWS region currently exists. The first one is Los Angeles, which belongs to the Oregon region (and not the California region).

3. How to Choose a Region/AZ

So that’s what they are — now how do you choose a region and availability zone for

Distance — choose regions close to you and your customers to keep latency low
Service availability — as we’ll discuss more below, there are some regions that offer more services than others, and new services will tend to be introduced in these regions first.
Cost — always check the AWS pricing calculator to compare the cost between regions. N. Virginia is usually the least expensive among others. Sao Paulo is typically the most expensive.
Compliance — GDPR, government contracting, and other regulated industries may require a specific region or multiple regions

4. What Sorts of Functions are Defined by Region and Availability Zone?

Regionless Services

Some services, like AWS IAM, do not support Regions. Therefore, the endpoints for those services do not include a Region. Other services, such as Amazon EC2, support Regions but, you are able to specify an endpoint that does not include a Region. Additionally, Amazon Simple Storage Service (Amazon S3), supports cross-Region replication.

AWS Regions introduced before March 20, 2019 are enabled by default. You can begin working in these Regions immediately. Regions introduced after March 20, 2019 are disabled by default — you must enable these Regions before you can use them. Administrators for an account can enable and disable Regions and use a policy condition that controls who can have access to AWS services in a particular AWS Region.

There are some less popular services such as Alexa for Business, Amazon Augmented AI (A2I), Amazon Fraud Detector, and Amazon Mobile Analytics are only available in the US East (N. Virginia) Region.

Region Differences Across Major Services

Amazon S3

Amazon Simple Storage Service (S3) is storage for the internet. You can use Amazon S3 to store and retrieve any amount of data at any time, from anywhere on the web.

You specify an AWS Region when you create your Amazon S3 bucket. For S3 Standard, S3 Standard-IA, and S3 Glacier storage classes, your objects are automatically stored across multiple devices ranging on a minimum of three Availability Zones, each separated across an AWS Region. Objects stored in the S3 One Zone-IA storage class are stored redundantly within a single Availability Zone in the AWS Region you select.

S3 operates in a minimum of three AZs, each separated by miles to protect against local events like fires, floods, etc. S3 is available in all Regions in North America, South America, Europe, Africa, China, Asia Pacific and the Middle East.

Amazon Elastic Compute Cloud

Amazon Elastic Compute Cloud (EC2) provides resizable, scalable computing capacity in the cloud. Each Amazon EC2 Region is designed to be isolated from the other Amazon EC2 Regions. This achieves the greatest possible fault tolerance and stability.

When you view your resources, you see only the resources that are tied to the Region that you specified. Why does this happen? Because Regions are isolated from each other, and resources are not automatically replicated across Regions.

When you launch an EC2 instance, you must select an AMI that’s in the same Region. If the AMI is in another Region, you can copy the AMI to the Region you’re using. When you launch an instance, you can select an Availability Zone or let Amazon choose one for you.

EC2 is available in all Regions in North America, South America, Europe, Africa, China, Asia Pacific and the Middle East.

AWS Lambda

AWS Lambda runs your code in response to triggers and automatically manages the compute resources for you. Lambda maintains compute capacity across multiple AZ’s in each Region in order to help protect code against individual machine or data center facility failures.

AWS Lambda is available in all Regions in North America, South America, Europe, Africa, China, Asia Pacific and the Middle East. The only region Lambda is not available in is Osaka, which is a local region. This type of region is new and is made up of an isolated fault-tolerant infrastructure design located in a single data center.

Amazon Simple Notification Service

Amazon SNS is a highly available, durable, secure, fully managed messaging service that allows you to decouple distributed systems, microservices, and serverless applications. SNS uses cross availability zone message storage to provide high message longevity.

Amazon SNS is available in all Regions in North America, South America, Europe, Africa, China, Asia Pacific and the Middle East.

Amazon EBS

Amazon Elastic Block Store (EBS) is AWS’s block-level, persistent local storage solution for Amazon EC2 that allows you to minimize data loss and recovery time while being able to regularly back up your data and log files across different geographic regions.

EBS volumes are replicated within an Availability Zone (AZ) and can easily scale to petabytes of data. Each volume is designed to protect against failures by replicating within the Availability Zone (AZ), offering 99.999% availability and an annual failure rate (AFR) of between 0.1%-0.2%. You can also quickly restore new volumes to launch applications in new regions.

EBS Snapshots can be used to quickly restore new volumes across a region’s Availability Zones, enabling rapid scale.

EBS is available in all Regions in North America, South America, Europe, Africa, China, Asia Pacific and the Middle East.

Transferring Data Between Regions Can Matter Too

Transferring data between AWS services within a region costs differently depending on whether you’re transferring data within or across AZs.

Data transfers are free if you are within the same region, same availability zone, and use a private IP address. Data transfers within the same region, but in different availability zones, have a cost associated with them.

So, to summarize, AWS Regions are separate geographic areas and within these regions are isolated locations that are known as Availability Zones (AZ). It’s important to pay attention to the services offered in each Region and AZ so you can make sure you are getting the most optimal service in your area.

Originally published at www.parkmycloud.com on March 19, 2020.