If you want data to be automatically synchronized between different instances across different regions in real time, you can convert an existing regular instance to the first child instance of a distributed (Global Distributed Cache) instance or create an instance as the first child instance. You can use a distributed instance in scenarios such as active geo-redundancy, disaster recovery, and data synchronization across regions.
Background information
Global Distributed Cache for Tair is an active geo-redundancy database system that is developed in-house by Alibaba Cloud. Global Distributed Cache for Tair uses synchronization channels to connect multiple child instances to form a logical distributed instance. All child instances are readable and writable. Data is synchronized in real time among the child instances. Global Distributed Cache for Tair supports business scenarios in which multiple sites in different regions provide services at the same time. It helps enterprises replicate the active geo-redundancy architecture of Alibaba. For more information, see Overview of Global Distributed Cache for Tair.
You are not charged for creating a distributed instance. Only child instances in the distributed instance are billed based on their specifications. Child instances are billed in the same manner as regular instances. For more information, see Billable items.
This feature also has specific limits. For more information, see Limits.
Procedure
If you have created a Tair DRAM-based instance that is deployed in classic mode, you can convert the instance. The system automatically creates a distributed instance and converts the existing instance to the first child instance of the distributed instance.
The first child instance can be converted from an existing instance. The second and third child instances must be newly purchased instances.
If no instance is created, you can purchase a Tair DRAM-based instance that is deployed in classic mode. The system automatically creates a distributed instance and uses the newly purchased instance as the first child instance of the distributed instance.
Convert an existing regular instance
During this process, the instance may experience transient connections that last for a few seconds and a change in the virtual IP address (VIP). To ensure a smooth conversion, take the following measures:
Use an endpoint, such as
r-hp3bpn39cs1vu****.redis.hangzhou.rds.aliyuncs.com, to connect to the instance.Make sure that your application can automatically reconnect to the instance.
Perform this operation during off-peak hours.
Log on to the console.
In the left-side navigation pane, click Global Distributed Cache.
In the upper-left corner of the page, choose .
Select an instance to convert it to the first child instance of a distributed instance.
Parameter
Description
Region
The region where the existing instance resides.
Deployment Mode
This parameter is set to Classic.
Edition
This parameter is set to Enterprise Edition and cannot be changed.
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.
For more information, see Overview.
Instance
Select the instance that you want to convert to the first child instance of a distributed instance.
Click OK.
NoteAfter the conversion is complete, the selected instance becomes the first child instance of the distributed instance. To prevent accidental operations, the console no longer displays the instance on the Instances page. You can click Global Distributed Cache in the left-side navigation pane and manage the instance in the distributed instance list.
Purchase an instance as a child instance
Log on to the console.
In the left-side navigation pane, click Global Distributed Cache.
In the upper-left corner of the page, choose .
On the buy page, configure the following parameters:
Service: Select Redis Open-Source Edition.
Billing Method:
Subscription: You must pay upfront for the instance that you create. 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. This billing method is suitable for short-term use. If you no longer require a pay-as-you-go instance, you can release the instance to reduce costs.
Deployment Mode: Select Classic.
Configure parameters for the child instance.
Parameter
Description
Region and Zone
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 Elastic Compute Service (ECS) instance to which you want to connect. Otherwise, the Tair instance and the ECS instance cannot communicate over the internal network to achieve optimal performance.
Deployment Type
Single-zone Deployment: The master and replica nodes are deployed in the same zone. This deployment type can provide single-data center disaster recovery.
Dual-zone Deployment: The master node and replica node 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 specific ECS instances are used to access a Tair instance, the instance that is deployed in the same zone as the ECS instances can be accessed at a slightly lower latency compared with the instance that is deployed in a different zone.
NoteIf 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.
ImportantTo enable connections over an internal network, make sure that the Tair instance is connected to the same network type as the ECS instances or ApsaraDB RDS instances that need to access the Tair instance.
If the VPC network type is selected, make sure that the Tair instance is connected to the same VPC as the ECS instances or ApsaraDB RDS instances that need to access the Tair instance.
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 that you want to connect to 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-threaded model. You can use high-performance cluster instances to process large-capacity workloads.
For more information, see Overview.
Shards
The number of shards for the cluster instance.
NoteThis parameter is available 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.
NoteDatabase metadata is generated when an instance is created. The size of the metadata on each shard of a cluster instance ranges 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: Specify a password after the instance is created. For more information, see Change or reset the password.
Now: Specify a password for the instance 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 specific special characters.
The following special characters are supported:
!@#$%^&*()_+-=
Resource Group
The resource group in which to create the instance.
Click Buy Now.
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 Creating to Running, the child instance is created.
What to do next
FAQ
Why is the
The gdc custins trans not supporterror returned?The instance that you want to convert to the first child instance of a distributed instance has a private endpoint allocated. Release the private endpoint and try again.
Related API operations
API operation | Description |
Creates a DRAM-based instance that is deployed in classic mode. You can use the instance as the first child instance of a distributed instance. You can also add the instance to an existing distributed instance and use the instance as the second or third child instance. | |
Converts the specified instance to the first child instance of a distributed instance. | |
Queries the details of a distributed instance. | |
Removes a child instance from a distributed instance and converts the child instance to a regular instance. During this process, data is retained. |