Help Center/ GeminiDB/ GeminiDB Cassandra API/ Working with GeminiDB Cassandra API/ Cross-region Dual-active DR/ Creating a Dual-Active Relationship
Updated on 2024-12-02 GMT+08:00
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Creating a Dual-Active Relationship

GeminiDB Cassandra API allows you to create a dual-active relationship for two instances in different regions, so that their data can be synchronized.

This section describes how to create such a dual-active relationship.

The current instance is the source instance, and you need to specify the target instance.

Precautions

  • This function is in the open beta test (OBT) phase. To use this function, contact customer service.
  • Before creating a dual-active relationship, create a target instance in a specific region and ensure it has the same or higher specifications and storage capacity than the source instance. To use a higher specification, contact customer service. The destination instance must have the same or higher specifications than the source to meet CPU or memory requirements.
  • Ensure the target instance has no additional tables before creating the dual-active relationship.
  • The target instance must have the same administrator password as the source instance.
  • To create a dual-active relationship again after it is removed, execute the DROP statement to clear tables in the target instance.
  • The source instance transfers all of its data to the target instance.

Constraints

1. Currently, only GeminiDB Cassandra API can be used to set up active-active instances, but GeminiDB HBase and DynamoDB cannot.

2. Currently, counter tables, TRUNCATE operations, and Lucene indexes cannot be synchronized between active-active instances.

Procedure

  1. Log in to the GeminiDB console.
  2. In the service list, choose Databases > GeminiDB Cassandra API.
  3. On the Instances page, locate the source instance that you want to create a dual-active relationship for and choose More > Create Dual-Active Relationship in the Operation column.

    Figure 1 Creating a dual-active relationship

  4. On the Create Dual-Active Relationship dialog box, locate the destination instance as the dual-active DR instance.

    Figure 2 Selecting the destination instance

    The destination instance must be in a different CIDR block from the source instance and has the same or higher specifications and no less nodes and storage space than the source, to synchronize data in real time between them and avoid subnet conflicts across regions.

  5. Click OK.
  6. On the Instances page, click before the source instance and view and manage its DR instance.

    • When the DR instance is being created, its status is Creating dual-active relationship.
    • After the creation is complete, the status changes to Available.

      You can click in the upper right corner of the page to refresh the instance status.