Delete zones from a cluster

This topic describes how to scale in a cluster by deleting zones from the cluster.

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

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

Procedure

Assume that the current cluster has five zones, zone1, zone2, zone3, zone4, and zone5, each zone contains one OBServer node, and you want to reduce the number of zones of the cluster to three.

1. Modify the obcluster.yaml configuration file to delete zone4 and zone5.

   # For example, the OceanBase cluster has five 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
         - name: zone4
           region: region1
           nodeSelector:
             ob.zone: zone3
           replicas: 1
         - name: zone5
           region: region1
           nodeSelector:
             ob.zone: zone3
           replicas: 1
   
   
   # Delete zone4 and zone5 from 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
   
   

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
   

   The preceding result shows that the cluster has only three zones, zone1, zone2, and zone3. zone4 and zone5 have been deleted.