Creating a DR Instance

Precautions

• A primary instance can have only one DR instance.
• This function is in the open beta test (OBT) phase. To use this function, contact customer service.

Prerequisites

A primary instance has been created.

Constraints

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

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

Creating a DR Instance

1. Log in to the GeminiDB console.
2. In the service list, choose Databases > GeminiDB Cassandra API.
3. On the Instances page, locate the primary instance you want to create a DR instance for and choose More > Create DR Instance in the Operation column.
4. On the displayed page, configure required parameters and click Next.

   Table 1 Basic information

   Parameter	Description
   Billing Mode	Select Yearly/Monthly or Pay-per-use. Yearly/Monthly In this mode, specify Required Duration at the bottom of the page. The system deducts the fees incurred from your account based on the service price. If you do not need such an instance any longer after it expires, change the billing mode to pay-per-use to optimize costs. For details, see Yearly/Monthly to Pay-per-Use. NOTE: Yearly/Monthly instances cannot be deleted directly. If such an instance is no longer required, unsubscribe from it. For details, see How Do I Unsubscribe from Yearly/Monthly Instances?. Pay-per-use If you select this billing mode, you are billed based on how much time the instance is in use. If you expect to use an instance for a long period of time, change its billing mode to yearly/monthly to optimize costs. For details, see Pay-per-Use to Yearly/Monthly.
   Region	The region is the same as that of the primary instance.
   DB Instance Name	The instance name: The name can include 4 to 64 bytes and must start with a letter. It is case-sensitive and allows only letters, digits, hyphens (-), and underscores (_).
   Compatible API	Cassandra
   DB Instance Type	Cluster
   DB Engine Version	The compatible API version is the same as that of the primary instance.
   CPU Type	The CPU type is the same as that of the primary instance.
   AZ	Availability zone where the instance is created. An AZ is a part of a region with its own independent power supplies and networks. AZs are physically isolated but can communicate through an internal network. An instance can be deployed in one or three AZs. If you want to deploy an instance in a single AZ, select one AZ. If you want to deploy your instance across AZs for disaster recovery, select three AZs. Nodes of the instance are evenly distributed across the three AZs.

   Table 2 Specifications and storage

   Parameter	Description
   Instance Specifications	vCPUs and memory of the instance. Different performance specifications support different connections and maximum IOPS. Select CPUs and memory based on your service requirements.. After an instance is created, you can change its vCPUs and memory by referring to Changing vCPUs and Memory of an Instance.
   Nodes	Specify the number of nodes based on service requirements. After an instance is created, you can add nodes by referring to Adding Nodes.
   Storage Space	Storage space depends on the instance specifications. The minimum storage space is 100 GB, and the storage space you set must be an integer. You can increase a minimum of 1 GB at a time. Enable autoscaling to ensure that the instance has sufficient storage and keeps available. To enable this function, just switch on button Configure Autoscaling and set the following parameters: If available storage drops to or below: The storage threshold for triggering autoscaling. When the percentage of available storage drops to or below the threshold you set or 10 GB, the system automatically scales up your instance storage. Increase by: The percentage that your instance storage will be scaled up at. If the increased storage is not a multiple of 10 GB, the system will round it up to the nearest multiple of 10 GB. At least 100 GB is added each time. Autoscaling Limit: Maximum amount that the system can automatically scale up an instance's storage space to. The value must be no less than the total storage of the instance and cannot exceed its maximum storage. After an instance is created, you can scale up its storage space by referring to Scaling Storage Space. NOTE: Once autoscaling is enabled, an agency will be created and fees will be automatically deducted from your account. Autoscaling is available only when you have the required permission. To enable this function, contact customer service. You can enable autoscaling after an instance is created. For details, see Configuring Auto Scale.

   Table 3 Network

   Parameter	Description
   VPC	The VPC of the DR instance remains unchanged by default.
   Subnet	The subnet of the DR instance remains unchanged by default. If you select another subnet in the same VPC, ensure that the selected subnet can be connected to the subnet of the primary instance.
   Security Group	The security group of the DR instance remains unchanged by default. Access from the 192.168.0.0/24 CIDR block in the security group should be allowed to ensure that DR instances can be created and work properly.
   SSL	A security protocol. Secure Sockets Layer (SSL) certificates set up encrypted connections between clients and servers, preventing data from being tampered with or stolen during transmission. You can enable SSL to improve data security. After an instance is created, connect to it through SSL.

   Table 4 Database configuration

   Parameter	Description
   Administrator	Username of the administrator account. The default value is rwuser.
   Administrator Password	The password must be the same as that of the primary instance to ensure that a switchover is performed in the event of a failure.
   Confirm Password	Enter the administrator password again.
   Parameter Template	A parameter template contains API configuration values that can be applied to one or more instances. After an instance is created, you can modify its parameters to better meet your service requirements. For details, see Modifying Parameters of GeminiDB Cassandra Instances.

   Table 5 Tags

   Parameter

   Description

   Tags

   The setting is optional. Adding tags helps you better identify and manage your instances. A maximum of 20 tags can be added for each instance. A tag consists of a tag key and a tag value. Tag key: Mandatory if the instance is going to be tagged Each tag key is unique for each instance. It can include up to 36 characters, including digits, letters, underscores (_), and hyphens (-). Tag value: Optional if the instance is going to be tagged The value can contain up to 43 characters, including digits, letters, underscores (_), periods (.), and hyphens (-). After an instance is created, you can view its tags on the Tags tab and can also add, modify, and delete tags of your instance. For details, see Managing Tags.

   Table 6 Required duration

   Parameter	Description
   Required duration	The length of your subscription if you select Yearly/Monthly billing. Subscription lengths range from one month to three years.
   Auto-renew	This option is not selected by default. If you select this option, the auto-renew cycle is determined by the selected required duration.

5. On the displayed page, confirm the instance details.
   • For yearly/monthly instances
     • To modify the configurations, click Previous.
     • If you do not need to modify the settings, read and agree to the service agreement, click Pay Now, and complete the payment.
   • For pay-per-use instances
     • To modify the configurations, click Previous.
     • If no modification is required, read and agree to the service agreement and click Submit.

6. On the Instances page, click in front of the primary instance to view and manage the DR instance.
   • During DR instance creation, the status of the primary instance is DR cluster being created, and the status of the DR instance is Creating. This process takes about 5 to 9 minutes.
   • 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.

   • During creation, an automated backup policy is enabled by default. A full backup is automatically triggered after an instance is created.