:Add a child instance to a distributed instance

Precautions

An added child instance must meet the following requirements:

Procedure

1. Log on to the Tair console.

2. In the left-side navigation pane, click Global Distributed Cache.

3. Find the distributed instance that you want to manage and click the icon before the instance ID.

4. On the right side of Child Instances, click Add Child Instance.

5. On the buy page, configure the following Product Type information.

   • Product Type: Select Redis (Local Disk, Including Tair).

   • Billing Method:

     • Subscription: You must pay for the instance when you create the instance. For long-term use, the subscription billing method is more cost-effective than the pay-as-you-go billing method. Alibaba Cloud provides lower prices for longer subscription durations.

     • Pay-as-you-go: You are charged on an hourly basis after you create the instance. For short-term use, we recommend that you select the pay-as-you-go billing method. If you no longer require a pay-as-you-go instance, you can release the instance to reduce costs.

6. Configure parameters for the child instance.

   Parameter	Description
   Region	The region in which you want to create the child instance. You cannot change the region after the instance is created. To maximize access speed, we recommend that you select a region that is close to the geographic location of your users. Make sure that the Tair instance is created in the same region as the ECS instance to which you want to connect. Otherwise, the ApsaraDB for Redis instance and the ECS instance cannot communicate over the internal network to achieve optimal performance.
   Deployment Type	Single-zone: The master and replica nodes are deployed in the same zone. This deployment type can provide single-data center disaster recovery. Dual-zone: The master and replica nodes are separately deployed in the specified primary and secondary zones of the same region to form a zone-disaster recovery architecture.
   Primary Zone	The zone in which you want to create the instance. Each region has multiple isolated locations known as zones. Each zone has its own independent power supply and network. All zones in a region provide the same level of service performance. If the Tair instance resides in the same zone as the ECS instance on which your application is deployed, these instances can deliver optimal performance. If the Tair instance and the ECS instance reside in different zones in the same region, the performance of the ApsaraDB for Redis instance and the ECS instance is slightly lower than the performance of the ApsaraDB for Redis instance and the ECS instance that reside in the same zone. Note If you set the Deployment Type parameter to Dual-zone Deployment, you must also set the Secondary Zone parameter to a zone that is different from the zone specified for the Primary Zone parameter. The primary and secondary zones form a master-replica zone-disaster recovery architecture.
   Network Type	The network type of the instance. This parameter can be set only to VPC. A virtual private cloud (VPC) is an isolated network that provides higher security and better performance than the traditional classic network. Important Make sure that the Tair instance uses the same network type as the ECS or ApsaraDB RDS instance to which you want to connect. Otherwise, the ECS or ApsaraDB RDS instance cannot access the Tair instance over the internal network. If the VPC network type is selected, make sure that the Tair instance belongs to the same VPC as the ECS or ApsaraDB RDS instance to which you want to connect.
   VPC	The VPC in which you want to create the instance. If you do not have a VPC, create one first. For more information, see Create and manage a VPC.
   VSwitch	The vSwitch to which you want to connect the instance in the VPC. If no vSwitches are available in the VPC in the current zone, create a vSwitch. For more information, see Create and manage a vSwitch.
   Edition	This parameter is set to Enhanced Edition (Tair) and cannot be changed.
   Series	This parameter is set to DRAM-based and cannot be changed. For more information, see DRAM-based instances.
   Version	This parameter is set to Redis 5.0 and cannot be changed.
   Architecture Type	Standard: uses the master-replica deployment model that provides high-performance caching services and ensures high data reliability. Cluster: eliminates bottlenecks that are caused by the single-threading model. You can use high-performance cluster instances to process large-capacity workloads. Select Standard or Cluster. For more information, see Overview.
   Shards	The number of shards in the Tair cluster instance. Note This parameter is supported only if the Architecture Type parameter is set to Cluster.
   Node Type	This parameter is set to Master-Replica and cannot be changed. A master-replica instance provides a master node and a replica node that are deployed in hot standby mode to support data persistence.
   Instance Class	The specifications of the instance. Each option contains a group of configurations, such as the memory capacity, maximum number of concurrent connections to the instance, and maximum bandwidth. For more information, see DRAM-based standard instances and DRAM-based cluster instances. Note Database metadata is generated when an instance is created. The size of the metadata on each shard of a cluster instance can range from 30 MB to 50 MB. The total size of the metadata on a cluster instance is equal to the total size of metadata on all shards of the cluster instance.
   Instance Name	The name of the instance. Specify a descriptive name that helps you identify the instance.
   Subscription Duration	If you select the Subscription billing method, you must specify a subscription duration and select whether to enable auto-renewal.
   Quantity	The number of instances that you want to create. The instances must have the same configurations. Set the value to 1.
   Set Password	Later: You want to set the password after the instance is created. For more information, see Change or reset the password. Now: You want to set the password immediately. The password must be 8 to 32 characters in length. The password must contain at least three of the following character types: uppercase letters, lowercase letters, digits, and special characters. The following special characters are supported: !@#$%^&*()_+-=
   Resource Group	The resource group in which to create the instance.

7. Click Buy Now.

8. On the Confirm Order page, read and accept the terms of service, and then complete the payment.

   When the state of the distributed instance changes from Modifying to Running, the child instance is created.

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