Create a secondary instance

Prerequisites

Before you create a secondary instance, ensure that the following conditions are met.

• You have created a cluster instance. For more information, see Purchase an instance.

• The cluster instance is in the Running state.

• The cluster instance is not a Standard Edition (Key-Value) series instance.

• The cluster instance does not have read-only nodes.

• The nodes of the cluster instance are not shared nodes.

Procedure

1. Log on to the OceanBase Management Console .

2. In the navigation pane on the left, click Instance List.

3. In the instance list, find the target cluster instance. In the Actions column, click More and select Create Secondary Instance. The purchase page appears.

   Note

   • Currently, only whitelisted users can purchase secondary instances. To request access, contact OceanBase technical support.

   • You can add a secondary instance only to a cluster instance that is in the Running state. Secondary instances cannot be cascaded. Currently, you can add only one secondary instance to a primary cluster instance.

4. By default, the Billing Method for the secondary instance is the same as that of the primary instance. Select the Instance Type, Series, Region, Deployment Solution, Zone, Node Specifications, Number of Nodes, Storage Type, Storage Size, Version, Quantity, and Subscription Duration for the secondary instance.

   Configuration parameters	Description
   Instance Type	Must be a cluster instance.
   Series	Must be the same as the primary instance. Secondary instances currently support only Standard Edition (Cloud Disk) and Standard Edition (Local Disk).
   Region	The geographical location of the secondary instance. It can be different from the primary instance. Currently, only some regions in China are supported: China (Hangzhou), China (Shanghai), China (Zhangjiakou), and China (Shenzhen). You cannot change the region after purchase.
   Deployment Solution	Optional. It can be different from the primary instance. However, the number of full-featured replicas must be the same.
   Zone	Optional. It can be different from the primary instance.
   Node Specifications	Optional. They can be different from the primary instance. The minimum node specifications for the secondary instance cannot be less than the node specifications of the primary instance × 0.33.
   Number of Nodes	Optional. It can be different from the primary instance. The default value is 3.
   Storage Type	Optional. It can be different from the primary instance.
   Storage Size	Optional. The storage size of the secondary instance cannot be smaller than the storage specification of the primary instance.
   Version	Must be the same as the primary instance. Currently, OceanBase Database V3.x, V4.2.0, and later versions support creating secondary instances.
   Quantity	The default value is 1.
   Subscription Duration	Optional. The expiration time of the secondary instance should be close to that of the primary instance.

5. Click Buy Now.

6. Review the Terms of Service and click Pay.

7. After your payment is successful, the newly created secondary instance appears in the Instance List.

   Note

   • The specifications for the primary and secondary instances and their tenants are maintained separately. However, you must ensure that the specifications of the secondary instance and its tenants match those of the primary instance.

   • The ratio of tenant specifications (CPU and memory) to cluster specifications in the secondary cluster is automatically kept consistent with the ratio in the primary cluster. The formula is as follows: secondary tenant specifications = secondary cluster specifications * (primary tenant specifications / primary cluster specifications).

   • After the secondary instance is created, it automatically syncs Data Definition Language (DDL) statements from the primary instance to create tenants, databases, tables, partitions, and account information. The secondary instance does not support executing DDL statements.

What to do next

1. On the Instance List page, you can view information about the secondary instance, such as its type, series, zone, specifications, storage space, billing method, tags, and status.

2. In the instance list, click the name of the secondary instance to open its cluster instance workbench. In the upper-right corner, click the More icon. From there, you can switch the secondary instance to a primary instance or upgrade/downgrade the secondary instance.

   Note

   These operations are available only when the secondary instance is in the Running state.

   

3. You can access the databases under the tenants of the secondary cluster instance in read-only mode.

   1. In the navigation pane on the left, click Tenant Management.

   2. In the tenant list, click the name of the target tenant to open the Tenant Workbench.

   3. In the upper-right corner, click Log on to Database.

      

   4. In the window that appears, select the account to log on with.

      Note

      You cannot create or delete databases or accounts on secondary cluster instances. The accounts available in the drop-down list are synced from the primary cluster instance.

      

   5. Click OK.

4. You can manually add a primary endpoint for the tenants of the secondary cluster instance. For more information, see Add a primary endpoint for a secondary instance tenant. By default, the primary endpoint of a secondary instance provides only read-only services. If a primary endpoint is not created, you cannot perform read operations.

Limits

Secondary cluster instances do not support the following operations:

• Creating or deleting tenants (data is synced from the primary cluster instance).

• Creating or deleting databases and accounts (data is synced from the primary cluster instance).

• Modifying parameters. Data is synced from the primary cluster instance. When a secondary instance is created, modified parameters from the primary instance are not synced. After the primary-secondary instance relationship is established, subsequent parameter changes on the primary instance are automatically synced to the secondary instance.

• You cannot perform backup or recovery operations.

FAQ

Q: Can the tenant specifications of a secondary cluster instance be modified?

A: No, they cannot. The tenant specifications of a secondary cluster instance cannot be adjusted separately because their configuration must remain consistent with the tenant specifications of the primary cluster instance. If the specifications of the secondary cluster instance are insufficient for the tenants, the tenant specifications are proportionally reduced. However, the minimum tenant specifications cannot be lower than 1 CPU core and 4 GB of memory.