What Are Regions and AZs?

Concepts

A region and availability zone (AZ) identify the location of a data center. You can create resources in a specific region and AZ.

• Regions are divided based on geographical location and network latency. Public services, such as Elastic Cloud Server (ECS), Elastic Volume Service (EVS), Object Storage Service (OBS), Virtual Private Cloud (VPC), Elastic IP (EIP), and Image Management Service (IMS), are shared within the same region. Regions are classified into universal regions and dedicated regions. A universal region provides universal cloud services for common tenants. A dedicated region provides specific services for specific tenants.
• An AZ contains one or more physical data centers. Each AZ has independent cooling, fire extinguishing, moisture-proof, and electricity facilities. Within an AZ, computing, network, storage, and other resources are logically divided into multiple clusters. AZs within a region are interconnected using high-speed optical fibers to support cross-AZ high-availability systems.

Figure 1 shows the relationship between the regions and AZs.

Figure 1 Regions and AZs

Selecting a Region

When selecting a region, consider the following factors:

• Geographical location

  It is recommended that you select the closest region for low network latency and quick access. Regions within the Chinese mainland provide the same infrastructure, BGP network quality, as well as resource operations and configurations. Therefore, if your target users are on the Chinese mainland, you do not need to consider the network latency differences when selecting a region.

  The countries and regions outside the Chinese mainland, such as Bangkok, Thailand, and Hong Kong (China), provide services for users outside the Chinese mainland. If your target users are in the Chinese mainland, these regions are not recommended due to a long access latency.

  • If you or your target users are in the Asia Pacific region, except the Chinese mainland, select the CN-Hong Kong, AP-Bangkok, or AP-Singapore region.
  • If you or your target users are in Africa, select the AF-Johannesburg region.
  • If you or your target users are in Europe, select the EU-Paris region.

Selecting an AZ

When deploying resources, consider your applications' requirements on disaster recovery (DR) and network latency.

• If your applications require high DR capability, you are advised to deploy resources in different AZs in the same region.
• If your applications require low latency between instances, you are advised to deploy resources in the same AZ.

Regions and Endpoints

Before you use an API to call resources, specify its region and endpoint. For more details, see Regions and Endpoints.