Add zones to a cluster

This topic describes how to scale out a cluster by adding zones to the cluster.

You can modify the obcluster.yaml configuration file of the OceanBase cluster to add zones.

The spec.topology.cluster[index1].zone attribute in the obcluster.yaml configuration file specifies the distribution of zones in the OceanBase cluster deployed in the cluster[index1] Kubernetes cluster. You can add zones to the OceanBase cluster by modifying the value of this attribute.

Prerequisites

Before you add zones to the OceanBase cluster, make sure that the following prerequisites are met:

• The server has sufficient resources for the new zones.

• ob-operator determines the distribution of OBServer nodes based on the setting of nodeSelector in the obcluster.yaml configuration file of OceanBase Database. Therefore, you must first configure labels for Kubernetes nodes. For more information, see Create a cluster.

Procedure

Assume that the current cluster has three zones, zone1, zone2, and zone3, each zone contains one OBServer node, and you want to scale out the cluster to five zones.

1. Modify the obcluster.yaml file to add zone4 and zone5.

   # For example, the OceanBase cluster has three zones.
   spec:
     topology:
       - cluster: cn
         zone:
         - name: zone1
           region: region1
           nodeSelector:
             ob.zone: zone1
           replicas: 1
         - name: zone2
           region: region1
           nodeSelector:
             ob.zone: zone2
           replicas: 1
         - name: zone3
           region: region1
           nodeSelector:
             ob.zone: zone3
           replicas: 1
   
   
   # Add zone4 and zone5 to the cluster.
   spec:
     topology:
       - cluster: cn
         zone:
         - name: zone1
           region: region1
           nodeSelector:
             ob.zone: zone1
           replicas: 1
         - name: zone2
           region: region1
           nodeSelector:
             ob.zone: zone2
           replicas: 1
         - name: zone3
           region: region1
           nodeSelector:
             ob.zone: zone3
           replicas: 1
         - name: zone4 # Newly added zone
           region: region1
           nodeSelector:
             ob.zone: zone4
           replicas: 1
         - name: zone5 # Newly added zone
           region: region1
           nodeSelector:
             ob.zone: zone5
           replicas: 1
   

2. Run the following command for the modification to take effect:

   kubectl apply -f obcluster.yaml
   

3. Run the following command to check whether the modification has taken effect:

   kubectl get pods -n obcluster
   

   Here is an example of the command output:

   NAME                      READY   STATUS    RESTARTS   AGE
   sapp-ob-test-cn-zone1-0   2/2     Running   0          8m9s
   sapp-ob-test-cn-zone2-0   2/2     Running   0          8m9s
   sapp-ob-test-cn-zone3-0   2/2     Running   0          8m9s
   sapp-ob-test-cn-zone4-0   2/2     Running   0          8m9s
   sapp-ob-test-cn-zone5-0   2/2     Running   0          8m9s
   

   If the values of READY are both 2/2 and the values of STATUS are both Running for the pods corresponding to zone4 and zone5, zone4 and zone5 are added to the cluster.