Creating a Cross-AZ Cluster Instance

Precautions

• Only some regions support multi-AZ cluster instances.
• To create a multi-AZ instance, ensure that there are three or more AZs available in the region.
• Multi-AZ deployment means that the components of an instance are deployed in three different AZs.

Deployment Architecture Comparison

• Single AZ

  If an instance is deployed in a single AZ, all components of the instance are deployed in the same AZ. By default, anti-affinity deployment is configured. With an anti-affinity deployment, your primary, secondary, and hidden nodes are deployed on different physical machines for high availability.

• Multiple AZs

  The components of an instance are deployed in three different AZs for disaster recovery.

  • Two dds mongos nodes are respectively deployed in two AZs. If one dds mongos node is added, it will be deployed in the third AZ.
  • The primary, secondary, and hidden shard nodes are randomly and evenly deployed in three AZs.
  Figure 1 Multi-AZ Deployment
  

Procedure

1. Log in to the management console.
2. Click in the upper left corner and select a region and a project.
3. Click in the upper left corner of the page and choose Databases > Document Database Service.
4. On the Instances page, click Buy DB Instance.
5. Configure the instance details and click Next.
   • AZ: Select three AZs as shown in Figure 2.
     Figure 2 Selecting multiple AZs
     
   • For details about other configuration items, see Buying a Cluster Instance.

6. Confirm the order as prompted and complete the payment.