Create a standby tenant for a primary tenant managed by another OCP cluster

OceanBase Cloud Platform (OCP) allows you to create a standby tenant for a primary tenant managed by another OCP cluster. When an OCP cluster switchover is performed upon a failure of the primary IDC, you can form a tenant-level high-availability Physical Standby Database solution by switching the standby tenant to the PRIMARY role to provide database services.

In an OCP cluster, a tenant managed by another OCP cluster is a remote tenant and is marked with a Remote tag.

Prerequisites

• Make sure that you have the following permissions:

  • Resource Permissions : Cluster Maintenance or Tenant Maintenance permission
  • Menu Permissions : Permission on the Overview menu of Tenants

• You use OceanBase Database V4.2 or later.

• The cluster in which you want to create a standby tenant is in the Running state.

• You have created leader and follower OCP clusters in the multi-cluster mode.

• You have logged on with an account that has the permissions to manage the cluster. For example, you act as the system administrator or the OCP tenant administrator.

• (Optional) You have created a parameter template by referring to Manage tenant parameter templates.

  If you need to create multiple tenants with the same parameter configuration, you can use a parameter template to avoid repeatedly configuring the same parameters.

• The following conditions are met before you enable the arbitration service for a tenant:

  • The arbitration service is added for the cluster to which the tenant belongs, and the service is in the RUNNING state.

  • The locality of the tenant includes two or four full-featured replicas.

  • The resources available on the server hosting the arbitration service meet the resource requirements.

    You can modify the resource requirements by using the following system parameters based on your business requirements. For more information, see Modify system parameters.

    • ocp.arbitration.min.remain.disk.size: the minimum size in MB of the clog disk on the arbitration service host required when the arbitration service is enabled for the tenant. The parameter value is in the (a,b) format, indicating the minimum clog disk sizes required when the tenant has two and four full-featured replicas, respectively. Default value: [12,24].
    • ocp.arbitration.max.cpu.used.percentage: the maximum CPU utilization in percentage (%) allowed on the arbitration service host when the arbitration service is enabled for the tenant. Default value: 90.
    • ocp.arbitration.max.memory.used.percentage: the maximum memory usage in percentage (%) allowed on the arbitration service host when the arbitration service is enabled for the tenant. Default value: 90.

Procedure

Perform the following steps to create a standby tenant for a primary tenant managed by another OCP cluster:

1. Log on to the OCP console.

2. In the left-side navigation pane, click Tenants . The Tenants page appears.

3. Click Create Tenant in the upper-right corner.

   

4. Configure the parameters in the Basic Information section.

   The following table describes the parameters.

   Parameter	Description
   Tenant Type	Select Standby Tenant .
   OCP Cluster of Primary Tenant	Select an OCP cluster other than the current OCP cluster.
   Cluster of Primary Tenant	Select the OceanBase cluster to which the primary tenant, which is a remote tenant, belongs.
   Primary Tenant	Select the primary tenant of the standby tenant.
   Cluster of Standby Tenant	Select the local OceanBase cluster to which the standby tenant belongs.
   Standby Tenant Name	Enter the name of the standby tenant. The tenant name can contain letters, digits, and underscores (_), and must be 2 to 64 characters in length.
   Primary/Standby Synchronization Method	The synchronization mode between the primary and standby tenants. Two synchronization modes are supported: Network-based Synchronization and Archiving-based . In Network-based Synchronization mode, logs are synchronized through the remote procedure call (RPC) network between OBServer nodes. A standby tenant can directly read logs from the primary tenant by using an IP address and a port number.By default, Network-based Synchronization mode is used. In Archiving-based mode, logs are synchronized based on shared storage. The primary tenant writes logs to a network disk or Alibaba Cloud Object Storage Service (OSS), and the standby tenant reads data from the shared storage. To use Archiving-based mode, make sure that archiving is enabled for the current tenant. Otherwise, data cannot be synchronized based on archiving. For more information, see Back up tenant now. Note If a primary/standby relationship (cascading or one-to-many) already exists, the primary/standby synchronization mode that is already in use is selected by default and cannot be modified.

   

5. Specify the backup set information in the Restore Standby Tenant Settings section. You can choose whether to specify an independent storage directory for the standby tenant based on your business scenario.

   Note

   If Network-based Synchronization mode is used and the REDO logs of the primary tenant are complete, you do not need to configure the standby tenant restoration settings. You can also click Restore by Using Backup Set and configure backup set information to restore the standby tenant by using the backup set.

   • Specify an independent storage directory

     Scenario: You have backed up the standby tenant by using a CLI instead of the tenant backup feature of OCP, or you have copied the external backup files of the primary tenant to a shared storage service and you want to restore the standby tenant by using the backup files.

     Parameter	Description
     Backup Set Storage Type	The storage service for the backup files. Valid values: File: Your local file storage system. Generally, Network File System (NFS) is used. OSS: Alibaba Cloud Object Storage Service (OSS), which is supported only in OceanBase Database V2.2.76 and later. COS: Tencent Cloud Object Storage (COS), which is supported only in OceanBase Database V2.2.76 or later but earlier than V4.0.0, and in OceanBase Database V4.2.1 and later.
     Data Backup Directory	The data storage directory on the current storage service for backup files.
     Log Backup Directory	The log storage directory on the current storage service for backup files.
     Domain	The domain name for accessing the cloud storage service where the backup set is stored. If you select OSS for Backup Set Storage Type , enter the domain name for accessing backup files in the OSS bucket. You can append a port number to the domain name, for example, oss.ap-shanghai.myqcloud.com:8080. If you select COS for Backup Set Storage Type , enter the domain name for accessing objects in the COS bucket, for example, cos.ap-beijing.myqcloud.com.
     User	The user for accessing the OSS bucket. This parameter is displayed only if you have selected OSS for Backup Set Storage Type .
     APPID	The unique resource identifier at the user dimension when you access the COS bucket as a developer. You can obtain the APPID on the API key management page of the corresponding product. This parameter is displayed only if you have selected COS for Backup Set Storage Type .
     Project ID	The project ID owned by a developer. You can obtain the ID on the API key management page of the corresponding product. This parameter is displayed only if you have selected COS for Backup Set Storage Type .
     Access Key	The user key for accessing the OSS or COS bucket. This parameter is displayed only if you have selected OSS or COS for Backup Set Storage Type .

   • Do not specify an independent storage directory

     Scenario: You have backed up the standby tenant by using the tenant backup feature of OCP. If you choose not to specify an independent storage directory, the system automatically populates the storage directory information, which cannot be modified.

     Parameter	Description
     Backup Directory	The backup directory on the current storage service for backup files. This parameter is displayed only if you have selected File or COS for Backup Set Storage Type .
     Storage Directory	The storage directory on the current storage service for backup files. This parameter is displayed only if you have selected OSS for Backup Set Storage Type .
     Domain	The domain name for accessing the cloud storage service where the backup set is stored. If you select OSS for Backup Set Storage Type , enter the domain name for accessing backup files in the OSS bucket. You can append a port number to the domain name, for example, oss.ap-shanghai.myqcloud.com:8080. The domain name for accessing objects in the COS bucket. This parameter is displayed only if you have selected COS for Backup Set Storage Type , for example, cos.ap-beijing.myqcloud.com.

   

   Click Backup Set Verification . The system checks the directory of the current backup set, whether the cluster of the standby tenant is accessible, and whether logs of the maximum restorable window of the current backup set and logs of the current primary tenant are consistent. If the check fails, you can locate and handle the issue based on the prompts.

6. Specify the information in the Standby Tenant Replica Settings section.

   Note

   We recommend that you keep the replica specifications of the standby tenant consistent with those of the primary tenant.

   By default, the system displays configurable zones based on the zone information of the selected cluster. If you do not need to create a replica in a zone, click the Delete icon to delete the zone. The following table describes the zone parameters.

   Parameter	Description
   Replica Type	The type of the replica. Valid values: Full-featured replica Read-only replica Select multiple full-featured replicas to ensure that they are in the majority. Note In a standalone centralized database, only full-featured replicas are supported.
   Unit Specification	OCP has a set of built-in unit specifications. You can select the specifications that you need from the list of unit specifications or click Add Specification at the bottom of the list to add custom specifications. For more information, see OCP resource unit specifications. Note We recommend that you set the same specifications and number of units for full-featured replicas to ensure performance and stability. If the OceanBase Database version of the cluster is V4.0.0 or later, take note of the following considerations: You cannot configure less than one CPU core for the tenant. By default, the cluster limits the minimum memory size. You can adjust the limit by modifying the __min_full_resource_pool_memory parameter. For example, if your cluster version is OceanBase Database V4.1.0, you can modify the parameter by referring to the Modify cluster parameters topic.
   Units	The number of units in the zone. The number of resource units cannot exceed the number of OBServer nodes in the zone. If the cluster version is OceanBase Database V4.0 or later, you can only set the same number of units for all zones, which is 1 by default. If the cluster version is earlier than OceanBase Database V4.0, you can set different numbers of units for different zones. Note In a standalone centralized database, the default number of units is 1, which cannot be modified.
   Zone Priority Rankings	Specifies whether to define priorities for the zones of the tenant. The priorities affect the priority of the primary zone of the sys tenant. If this parameter is not specified, the zone priorities of the sys tenant are used by default. If Zone Priority Rankings is enabled while no zone priorities, the random priority is used. To configure zone priorities, you can select one or more zones from the list on the left that displays all zones in the current cluster and add the selected zones to the list on the right. By default, the priority of a zone added earlier is higher than that of a zone added later, and the zones added at the same time have the same priority. After you move the zones to the box on the right side, you can also drag them upward or downward to adjust their priority order. A zone takes priority over those beneath it. Note In a standalone centralized database, the zone priority rankings are not displayed, and Zone1 has the highest priority.
   Enable Arbitration Service	Specifies whether to enable the arbitration service for the tenant. The arbitration service is disabled by default.

   

7. Enable Parameter Configurations and configure the tenant parameters.

   • You can click the button in section ① of the following figure to add startup parameters one by one and set their values.

   • You can also click Select Parameter Template as shown in section ② of the following figure and select a parameter template. The system will automatically populate parameters in this section by using the template.

   Note

   • If you are creating a tenant in MySQL mode by using a parameter template that contains parameters that are valid only in Oracle mode, you must manually delete those parameters.
   • If no tenant parameter template is available, you can click Create Tenant Parameter Template to create one. For more information, see Manage tenant parameter templates.

   

8. Click Submit .

   The page that appears prompts you that the tenant creation task has been submitted and displays the summary information of the task.

   • To view the task details, click View Task Details .
   • To return to the Tenants list, click Return to Tenants List . In the Tenants list, you can view the status and task details of the new tenant, and delete the tenant if the tenant creation failed.

   Note

   When the task status is Completed, you can check the status of the new tenant in the Tenants list on the Tenant Management page. The new tenant is created if its status is Running.