Creating a Replica Set Instance

Scenarios

This section describes how to create a DDS replica set instance on the DDS management console. DDS allows you to tailor your computing resources and storage space to your business needs.

You can use your account to create a maximum of 50 replica set instances in total. To create more replica set instances, click in the upper right corner of the management console. On the Service Quota page, click Increase Quota to apply for quotas.

Procedure

1. Log in to the DDS console.
2. On the Instance Management page, click Create DB Instance.
3. On the displayed page, configure parameters about DB instance specifications. Then, click Create Now.

   Table 1 Basic information

   Parameter	Description
   Region	A region where the tenant is located. It can be changed in the upper left corner. For details, see section Regions and AZs. NOTE: DB instances in different regions cannot communicate with each other through a private network, and you cannot change the region of a DB instance once it is created. Therefore, exercise caution when selecting a region.
   DB Instance Name	The DB instance name can be 4 to 64 characters long. It must start with a letter and can contain only uppercase letters, lowercase letters, digits, hyphens (-), and underscores (_). After the DB instance is created, you can change the DB instance name. For details, see section Modifying the DB Instance Name.
   Database Type	Community Edition
   DB Instance Type	Select Replica set. A replica set consists of the primary node, secondary node, and hidden node. If a primary node goes down or becomes faulty, a secondary node is automatically assigned to the primary role and continues normal operation. If a secondary node is unavailable, a hidden node will take the role of the secondary to ensure high availability.
   Compatible MongoDB Version	3.4 3.2
   Storage Engine	WiredTiger
   AZ	A physical region where resources use independent power supply and networks. AZs are physically isolated but interconnected through the internal network. For details, see section Regions and AZs. A replica set instance can be deployed in one AZ or three AZs only. If the replica set instance is deployed across three AZs, the primary, secondary, and hidden nodes are deployed in three AZs respectively for high availability.
   Disk Encryption	Disable: Disable the encryption function. Enable: Enable the encryption function. This feature improves data security but slightly affects read/write performance. Key Name: Select or create a private key, which is the tenant key. NOTE: After a DB instance is created, the disk encryption status and the key cannot be changed. Backup data stored on OBS is not encrypted. The key cannot be disabled or deleted when being used. Otherwise, the database becomes unavailable. For details about how to create a key, see the "Creating a CMK" section in the Key Management Service User Guide.

   Table 2 Specifications

   Parameter	Description
   Node Class	For details about the DB instance specifications, see section DB Instance Specifications. After a DB instance is created, you can change its CPU and memory. For details, see section Changing the CPU or Memory of a Replica Set DB Instance.
   Storage Type	Ultra-high I/O: uses the SSD disk type.
   Storage Space	Ranges from 10 GB to 2,000 GB. The value must be a multiple of 10.

   Table 3 Network

   Parameter	Description
   VPC	The VPC to which a DB instance belongs isolates networks for different services. It allows user to manage and configure internal networks and change network configuration, simplifying network management. You need to create or select the required VPC. For details on how to create a VPC, see section "Creating a VPC" in the Virtual Private Cloud User Guide.
   Subnet	A subnet provides dedicated network resources that are logically isolated from other networks, improving network security. After a DB instance is created, you can click the DB instance name and change the private IP address assigned by the subnet to the node on the Basic Information page. NOTE: Changing the private IP address of a node will invalidate the previous private IP address. If an EIP is bound to the node, do not unbind the EIP during the change of the private IP address. After the change, the new private IP address is bound to the EIP.
   Security Group	A security group controls access between DDS and other services for security. NOTE: Ensure that the security group rule you set allows clients to access DB instances. For example, select the TCP protocol with inbound direction, input the default port number 8635, and enter a subnet IP address or select a security group that the DB instance belongs to.
   SSL	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 a DB instance is created, you can connect to it in SSL mode. For details, see Connecting to a DB Instance Through a Client.

   Table 4 Database configuration

   Parameter	Description
   Administrator	The default account is rwuser.
   Administrator Password	The password is a string of 8 to 32 characters. It must be a combination of uppercase letters, lowercase letters, digits, and special characters. You can also use the following special characters: ~!@#%^*-_=+? The system cannot save you password. Keep the password secure.
   Confirm Password	The value of this parameter must be the same as the Administrator Password.
   Replica Set Parameter Group	The parameters in the replica set parameter group are applied to replica set instances. After a DB instance is created, you can change the parameter group of the instance. For a parameter group created by users, you can modify the parameters in the parameter group to bring out the best performance. For details, see Parameter Group.

   Table 5 Tag

   Parameter

   Description

   Tags

   Tags a DDS DB instance. This configuration is optional. Adding tags to DDS DB instances helps you better identify and manage them. Each DB instance can have up to 20 tags. A tag is composed of a key-value pair. Key: Mandatory if the DB instance is going to be tagged For each DB instance, each tag key is unique. A tag key consists of a maximum of 36 characters. The key can only consist of digits, letters, underscores (_), hyphens (-), and at sign (@). Value: Optional if the DB instance is going to be tagged The value consists of a maximum of 43 characters. The value can only consist of digits, letters, underscores (_), hyphens (-), and at sign (@). After a DB instance is created, you can view its tag details on the Tags tab. In addition, you can add, modify, and delete tags for existing DB instances. For details, see Tag.

   

   The performance of your DB instance is determined by how you configure it during the creation. The hardware configuration items that can be selected include the class and storage space of the replica set.

4. On the displayed page, confirm the DB instance information.
   • If you need to modify the specifications, click Previous to modify parameters.
   • If you do not need to modify the specifications, click Submit to start the instance creation.

5. After a DDS DB instance is created, you can view and manage it on the Instance Management page.
   • When a DB instance is being created, the status displayed in the Status column is Creating. This process takes about 15 minutes. After the creation is complete, the status changes to Available.
   • DDS enables the automated backup policy by default. After a DB instance is created, you can modify or disable the automated backup policy. An automated full backup is immediately triggered after the creation of a DB instance.
   • You can change the database port after the DB instance is created. DDS uses port 8635 by default, which is different from the default port numbers used by databases. To ensure database accessibility, you need to add the required security group rule.