Creating a DR Instance

Usage Notes

• A primary instance can have only one DR instance.
• This function is now in OBT. To use it, choose Service Tickets > Create Service Ticket in the upper right corner of the console and contact the customer service.

Prerequisites

A primary instance has been created.

Constraints

1. Currently, a DR instance can be provisioned for a GeminiDB Cassandra instance but is unavailable for GeminiDB HBase and DynamoDB-Compatible instances.

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

Creating a DR Instance

1. Log in to the Huawei Cloud console.
2. In the service list, choose Databases > GeminiDB.
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 Specify Required Duration. The system deducts fees 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. For details, see Changing a Yearly/Monthly Instance 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 a Yearly/Monthly Instance?. Pay-per-use If you select this billing mode, you are billed based on how much time the instance is in use. To use an instance for a long time, change its billing mode to yearly/monthly to reduce costs. For details, see Changing a Pay-per-Use Instance 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 with each other over a private network. Instances can be deployed in a single AZ or three AZs. To deploy instances in a single AZ, select one AZ. To deploy instances across AZs for disaster recovery, select three AZs, where the instance nodes will be evenly distributed.

   Table 2 Specifications and storage

   Parameter	Description
   Instance Specifications	vCPUs and memory of the instance. Performance specifications vary depending on the connections and maximum IOPS. After an instance is created, you can change its specifications. For details, see Changing vCPUs and Memory.
   Nodes	Specify the number of nodes based on service requirements. After an instance is created, you can add nodes by referring to Manually Adding Instance 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. You are advised to enable Auto Scale and set trigger conditions and storage limit. After autoscaling is triggered, the system automatically scales up the storage to ensure that the instance has sufficient storage and keeps available. Take care with the following parameters: Trigger If Available Storage Drops To: storage threshold for triggering autoscaling. When the available storage usage drops to a specified threshold or the available storage drops to 10 GB, autoscaling is triggered. Increase By: 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. Storage Limit: maximum amount that the system can automatically scale up an instance's storage to. The value must be no less than the current storage of your instance and cannot exceed the maximum storage supported by your instance. After an instance is created, you can scale up its storage if necessary. For details, see Manually Scaling Up Storage Space. NOTE: Once Auto Scale is enabled, an agency will be created and fees will be automatically deducted. Autoscaling is available only to users with required permissions. To use it, choose Service Tickets > Create Service Ticket in the upper right corner of the console and contact the customer service. You can enable Auto Scale after an instance is created. For details, see Automatically Scaling Up Storage Space.

   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. A tag key is mandatory if the instance is going to be tagged. Each tag key is unique for each instance. It can contain 1 to 128 characters, cannot start with _sys_, and cannot start or end with a space. Only letters, digits, spaces, and the following special characters are allowed: -_@.:/+= A tag value is optional if the instance is going to be tagged. The value can be empty. The value can contain a maximum of 255 characters. Only letters, digits, spaces, and the following special characters are allowed: _.-:+=@/ 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 GeminiDB Cassandra Instance 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.
   • Yearly/Monthly
     • 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.
   • Pay-per-use
     • 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 instance is created, its status becomes Available.

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

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