Manage replicas

This topic describes how to manage tenant replicas by using ob-operator.

Modify the primary zone of a tenant

You can modify the priority parameter of zones in the tenant configuration file to modify the primary zone of a tenant. A larger number indicates a higher priority. The minimum value is 1.

The primary zone describes the preferred location of the leader. The leader handles strong-consistency read traffic and write traffic of the business. Therefore, the primary zone determines the traffic distribution of OceanBase Database. You can modify the primary zone to switch business traffic from one IDC to another or from one city to another in disaster recovery and scaling scenarios.

Procedure

Modify the tenant configuration file tenant.yaml to adjust the priority value for each zone.

- zone: zone1
  priority: 1
- zone: zone2
  priority: 1
- zone: zone3
  priority: 3

# After modification
- zone: zone1
  priority: 3
- zone: zone2
  @priority 2
- zone: zone3
  priority: 1

The preceding configuration changes the primary zone of the tenant from zone3;zone1,zone2 to zone1;zone2;zone3.

Run the following command for the modification to take effect:
```
kubectl apply -f tenant.yaml
```
Run the following command to view the custom resources of the tenant in the current Kubernetes cluster to check whether the modification is successful:
```
kubectl get obtenants.oceanbase.oceanbase.com -n oceanbase -o yaml
```
If the value of the corresponding parameter in the status.resourcePool.priority section in the custom resources of the tenant is changed to the new value, the modification is successful.
```
status:
  ...
  resourcePool:
    - zone: zone1
      priority: 3
    - zone: zone2
      @priority 2
    - zone: zone3
      priority: 1
```
You can also run the following command to view the result.
```
kubectl get obtenants.oceanbase.oceanbase.com -n oceanbase -o wide
```
The command output is as follows:
```
NAME   STATUS    TENANTNAME   TENANTROLE   CLUSTERNAME   AGE   LOCALITY   PRIMARYZONE           POOLLIST    CHARSET
t1     running   t1           PRIMARY      obcluster     13m   ...        zone1;zone2;zone3     ...         utf8mb4
```
The result shows that the value of the PRIMARYZONE field is modified to zone1;zone2;zone3, which matches the priority configuration.

Modify the locality of a tenant

To modify the locality of a tenant, you can modify the parameters in the type section to specify the replica type and the number of replicas. The following replica types are supported: full, logonly, and readonly.

For more information, see [Modify the primary zone of a tenant](# Modify the primary zone of a tenant).

Modify the tenant configuration file tenant.yaml:

 type:
    name: Full # The Full and Readonly replica types are supported.
    replica: 1

Add replicas

Prerequisites

You have added a zone to the cluster. For more information, see Add zones to a cluster.

Procedure

You can add zones to a tenant by modifying the tenant configuration file tenant.yaml.

Assume that the current cluster has four zones, zone1, zone2, zone3, and zone4, the zones corresponding to the tenant are zone1, zone2, and zone3, and you want to scale out the tenant to four zones.

Modify the configuration file tenant.yaml to add zone4.

# For example, the tenant has three zones.
pools:
  - zone: zone1
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone2
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone3
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...

# Add zone4 to the tenant.
pools:
  - zone: zone1
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone2
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone3
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone4
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...

Run the following command for the modification to take effect:
```
kubectl apply -f tenant.yaml
```

Run the following command to view the custom resources of the tenant in the current Kubernetes cluster:

kubectl get obtenants.oceanbase.oceanbase.com -n oceanbase -o wide

The following command output shows that the value of the LOCALITY field is as expected:

NAME   STATUS    TENANTNAME   TENANTROLE   CLUSTERNAME   AGE   LOCALITY                                                       PRIMARYZONE           POOLLIST    CHARSET
t1     running   t1           PRIMARY      obcluster     19m   FULL{1}@zone1,FULL{1}@zone2,FULL{1}@zone3,FULL{1}@zone4        ...                   ...         utf8mb4

Delete replicas

Procedure

You can modify the tenant configuration file tenant.yaml to delete zones from a tenant.

Assume that the current cluster has four zones, zone1, zone2, zone3, and zone4, the zones corresponding to the tenant are zone1, zone2, zone3, and zone4, and you want to scale in the tenant to zone1, zone2, and zone3.

Modify the configuration file tenant.yaml to delete zone4.

# For example, the tenant has four zones.
pools:
  - zone: zone1
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone2
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone3
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone4
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...

# Delete zone4 from the tenant.
pools:
  - zone: zone1
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone2
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...
  - zone: zone3
    unitNum: 1
    type:
      name: Full
      replica: 1
    priority: 3
    resource:
      ...

Run the following command for the modification to take effect:
```
kubectl apply -f tenant.yaml
```

Run the following command to view the custom resources of the tenant in the current Kubernetes cluster:

kubectl get obtenants.oceanbase.oceanbase.com -n oceanbase -o wide

The following command output shows that the value of the LOCALITY field is as expected:

NAME   STATUS    TENANTNAME   TENANTROLE   CLUSTERNAME   AGE   LOCALITY                                     PRIMARYZONE     POOLLIST    CHARSET
t1     running   t1           PRIMARY      obcluster     25m   FULL{1}@zone1,FULL{1}@zone2,FULL{1}@zone3    ...             ...         utf8mb4

Manage replicas

Modify the primary zone of a tenant​

Procedure​

Modify the locality of a tenant​

Add replicas​

Prerequisites​

Procedure​

Delete replicas​

Procedure​

Modify the primary zone of a tenant

Procedure

Modify the locality of a tenant

Add replicas

Prerequisites

Procedure

Delete replicas

Procedure