Help Center/ Elastic Cloud Server/ Drawer/ Purchasing an ECS/ Basic Configurations/ AZ
Updated on 2025-11-26 GMT+08:00
Share

AZ

Description

  • Availability zone (AZ)

    An AZ may have one or more physical data centers where resources use independent power supplies and networks. AZs are physically isolated but interconnected through an internal network.

    There are multiple AZs in each region. If one AZ becomes faulty, other AZs in the same region continue to provide services.

    Figure 1 shows the relationship between regions and AZs.

    Figure 1 Regions and AZs
  • Random allocation

    Random AZ allocation is available on the console when you create an ECS. The cloud platform will select a default AZ for you based on your universally unique identifier (UUID).

    The available ECS types and flavors vary by AZ. To view all supported ECS types and flavors on the cloud service platform, set AZ to Random. The system automatically allocates an AZ according to your selected ECS flavor.

    For example, S6 ECSs are available only in AZ 1; S3 ECSs are available for sale in AZ 2 and AZ 3 but have been sold out in AZ 1. If you set AZ to Random, you can view both S6 and S3 ECSs. If you purchase an S6 ECS, the system automatically allocates it to AZ 1. If you purchase an S3 ECS, the system randomly allocates it to AZ 2 or AZ 3.

    If you purchase multiple ECSs in a batch and want to deploy them in different AZs, select Randomly allocated to multiple AZs.

FAQs

Can ECSs in Different AZs Communicate with Each Other over a Private Network?

Yes. ECSs in different AZs of the same region can communicate with each other over a private network. ECSs in the AZs of different regions, however, cannot. You can assign EIPs to the ECSs to enable them to communicate with each other over the Internet.

How Do I Select an AZ?

When deploying resources, consider your application requirements for disaster recovery (DR) and network latency.

  • If your applications require robust DR capabilities, deploy resources in different AZs within the same region.
  • For lower network latency, deploy resources in the same AZ.

Can I Change the AZ Where My ECS Is Deployed?

No, you cannot change the AZ of an ECS.

If you want to migrate an ECS to another AZ, you can create a private image from the ECS and use the private image to create identical ECSs in the target AZ.

To do so, switch to the Elastic Cloud Server page, locate the target ECS and choose More > Manage Image > Create Image in the Operation column.

Parent Topic: Basic Configurations