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Regions and Availability Zones
Amazon EC2 is hosted in multiple locations world-wide. These locations are composed of regions and Availability Zones. Each region is a separate geographic area. Each region has multiple, isolated locations known as Availability Zones. Amazon EC2 provides you the ability to place resources, such as instances, and data in multiple locations. Resources aren't replicated across regions unless you do so specifically.
Amazon operates state-of-the-art, highly-available data centers. Although rare, failures can occur that affect the availability of instances that are in the same location. If you host all your instances in a single location that is affected by such a failure, none of your instances would be available.
Topics
Region and Availability Zone Concepts
Each region is completely independent. Each Availability Zone is isolated, but the Availability Zones in a region are connected through low-latency links. The following diagram illustrates the relationship between regions and Availability Zones.
Some Amazon EC2 resources are tied to a region and others are tied to an Availability Zone. For example, an instance is tied to an Availability Zone and an Amazon EBS volume is tied to a region. For more information, see Resource Locations.
Regions
Each Amazon EC2 region is designed to be completely isolated from the other Amazon EC2 regions. This achieves the greatest possible fault tolerance and stability.
Amazon EC2 provides multiple regions so that you can launch Amazon EC2 instances in locations that meet your requirements. For example, you might want to launch instances in Europe to be closer to your European customers or to meet legal requirements.
When you view your resources, you'll only see the resources tied to the region you've specified. This is because regions are isolated from each other, and we don't replicate resources across regions automatically.
When you work with an instance using the command line interface or API actions, you must specify its regional endpoint. For example, to access the US East (Northern Virginia) Region, specify the ec2.us-east-1.amazonaws.com service endpoint. For more information about the regions and endpoints for Amazon EC2, see Regions and Endpoints in the Amazon Web Services General Reference.
When you launch an 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. For more information, see Copying AMIs.
All communications between regions is across the public Internet. Therefore, you should use the appropriate encryption methods to protect your data. Data transfer between regions is charged at the Internet data transfer rate for both the sending and the receiving instance. For more information, see Amazon EC2 Pricing - Data Transfer.
Availability Zones
You can list the Availability Zones that are available to your account. For more information, see Describing Your Regions and Availability Zones.
When you launch an instance, you can select an Availability Zone or let us chose one for you. If you distribute your instances across multiple Availability Zones and one instance fails, you can design your application so that an instance in another Availability Zone can handle requests.
You can also use Elastic IP addresses to mask the failure of an instance in one Availability Zone by rapidly remapping the address to an instance in another Availability Zone. For more information, see Elastic IP Addresses (EIP).
To ensure that resources are distributed across the Availability Zones for a region, we independently map
Availability Zones to identifiers for each account. For example, your Availability Zone
us-east-1a might not be the same location as us-east-1a for another account.
Note that there's no way for you to coordinate Availability Zones between accounts.
As Availability Zones grow over time, our ability to expand them can become constrained. If this happens, we might restrict you from launching an instance in a constrained Availability Zone unless you already have an instance in that Availability Zone. Eventually, we might also remove the constrained Availability Zone from the list of Availability Zones for new customers. Therefore, your account might have a different number of available Availability Zones in a region than another account.
Describing Your Regions and Availability Zones
You can use the AWS Management Console or the Amazon EC2 command line interface to determine which regions and Availability Zones are available for your use.
AWS Management Console
To find your regions and Availability Zones
Sign in to the AWS Management Console and open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
From the navigation bar, view the options in the region selector.
After you select a region, you can view your Availability Zones within that region when you launch an instance or create an Amazon EBS volume.
In the navigation pane, click Volumes.
View the options in the Availability Zones list.
When you are finished, click Cancel.
Command Line Interface
Use the following command to describe your regions.
PROMPT>ec2-describe-regionsREGION ap-northeast-1 ec2.ap-northeast-1.amazonaws.com REGION ap-southeast-1 ec2.ap-southeast-1.amazonaws.com ..
Use the following command to describe the Availability Zones within the
us-east-1 region.
PROMPT>>ec2-describe-availability-zones --region us-east-1AVAILABILITYZONE us-east-1a available us-east-1 AVAILABILITYZONE us-east-1b available us-east-1 AVAILABILITYZONE us-east-1c available us-east-1 AVAILABILITYZONE us-east-1d available us-east-1
Specifying the Region for a Resource
Every time you create an Amazon EC2 resource, you can specify the region for the resource. This section explains how to specify the region for a resource.
AWS Management Console
To specify the region for a resource
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
Use the region selector in the navigation bar.
Command Line Interface
To specify the region to use for all commands, set the value of the EC2_URL
environment variable to the regional endpoint.
For example, https://ec2.us-west-1.amazonaws.com.
Alternatively, you can use the --region or -U command line option
with each individual command.
For example, --region us-west-1 or -U https://ec2.us-west-1.amazonaws.com.
For more information about the endpoints for Amazon EC2, see Amazon Elastic Compute Cloud Endpoints.
Launching Instances in an Availability Zone
When you launch an instance, select a region that puts your instances closer to specific customers, or meets the legal or other requirements you have. By launching your instances in separate Availability Zones, you can protect your applications from the failure of a single location.
When you launch an instance, you can optionally specify an Availability Zone in the region that you are using. If you do not specify an Availability Zone, we select one for you. When you launch your initial instances, we recommend that you accept the default Availability Zone, because this enables us to select the best Availability Zone for you based on system health and available capacity. If you launch additional instances, only specify an Availability Zone if your new instances must be close to, or separated from, your running instances.
AWS Management Console
To specify an Availability Zone for your instance
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
On the dashboard, click Launch Instance.
Follow the directions for the wizard to launch the instance. You can select one of the Availability Zone options from the list, or select
No preferenceto enable us to select the best Availability Zone for you.
Command Line Interface
To specify an Availability Zone for your instance, use the --availability-zone
option with the ec2-run-instances command.
PROMPT>ec2-run-instancesami_id--availability-zonezone
API and Command Overview
The following table summarizes the available commands and corresponding API actions for regions and Availability Zones.
| Description | Command and API Action |
|---|---|
|
Describes the Availability Zones that are available to you. | |
|
Describes the regions that are available to you. |
