A distributed instance starts with one child instance. Add a second or third child instance to enable real-time data synchronization across zones. A single distributed instance can contain up to three child instances.
Prerequisites
Before you begin, ensure that you have:
A distributed instance already created. For more information, see Create a distributed instance.
Limitations
| Requirement | Details |
|---|---|
| Zone | The new child instance must be in a different zone from all existing child instances. |
| Architecture, version, and specifications | Must match all existing child instances. For example, if existing child instances are 8 GB cluster architecture instances with 2 shards compatible with Redis 7.0, the new child instance must use the same configuration. |
| Creation method | Child instances must be created as new instances. Existing instances cannot be converted into child instances. |
Mismatched specifications may cause performance or capacity issues.
Add a child instance
Log on to the Tair and Redis console.
In the left-side navigation pane, click Global Distributed Cache.
Find the target distributed instance and click the
icon to the left of the instance ID.To the right of the Child Instances list, click Add Child Instance.
On the purchase page, configure the parameters described below. Parameters that must match existing child instances — these values are fixed and must be consistent:
Parameter Requirement Version Must match existing child instances Architecture Type Must match existing child instances Shard Must match existing child instances Parameters to configure for the new child instance:
Parameter Description Service Select Tair (Enterprise Edition). Billing Method Select Subscription or Pay-as-you-go. See Choose a billing method. Region and Zone Settings Select a region and zone. The zone must differ from all existing child instances. VPC and vSwitch Select a Virtual Private Cloud (VPC) and a vSwitch. Password Settings Set to Now and enter a password. Subscription Duration (Subscription only) Set the subscription duration. Click Buy Now.
On the Confirm Order page, read the Terms of Service and complete the payment. The child instance is ready within 1–5 minutes. When the instance status changes to Running, the child instance has been added successfully. You can verify this in the Child Instances list of the distributed instance.
Choose a billing method
| Billing method | Best for | How you're charged |
|---|---|---|
| Subscription | Long-term use | Pay upfront. Longer durations get lower prices. |
| Pay-as-you-go | Short-term or variable use | Charged hourly. Release the instance when no longer needed to stop charges. |
API reference
| Operation | Description |
|---|---|
| CreateTairInstance | Creates a memory-optimized instance as the first child instance in a distributed instance, or adds it as the second or third child instance. |
| CreateGlobalDistributeCache | Converts a specified instance into the first child instance of a distributed instance. |
| DescribeGlobalDistributeCache | Queries detailed information about a distributed instance. |
| RemoveSubInstance | Removes a child instance from a distributed instance and converts it into a standard instance (data is preserved). |