Add OBServer nodes to zones

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

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

The spec.topology.cluster[index1].zone[index2].replicas attribute in the obcluster.yaml configuration file specifies the number of OBServer nodes in the [index2] zone of the OceanBase cluster deployed in the [index1] Kubernetes cluster. You can modify the value of this attribute to add OBServer nodes to a zone.

Prerequisites

Before you add an OBServer node to a zone, make sure that the server has sufficient resources for the new OBServer node.

Procedure

Assume that the current cluster has three zones, zone1, zone2, and zone3, each zone contains one OBServer node, and you want to add one OBServer node to each zone so that each zone contains two OBServer nodes.

1. Modify the obcluster.yaml configuration file and change the value of replicas from 1 to 2 for each zone.

   # For example, each zone has one OBServer node.
   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 an OBServer node to each zone.
   spec:
     topology:
       - cluster: cn
         zone:
         - name: zone1
           region: region1
           nodeSelector:
             ob.zone: zone1
           replicas: 2 # 1 -> 2
         - name: zone2
           region: region1
           nodeSelector:
             ob.zone: zone2
           replicas: 2 # 1 -> 2
         - name: zone3
           region: region1
           nodeSelector:
             ob.zone: zone3
           replicas: 2 # 1 -> 2
   

2. You can modify the number of OBServer nodes for multiple zones at a time. 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 pod -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          84m
   sapp-ob-test-cn-zone3-0   2/2     Running   0          84m
   sapp-ob-test-cn-zone2-0   2/2     Running   0          84m
   sapp-ob-test-cn-zone1-1   2/2     Running   0          3m40s
   sapp-ob-test-cn-zone2-1   2/2     Running   0          3m40s
   sapp-ob-test-cn-zone3-1   2/2     Running   0          3m39s
   

   The preceding result shows that zone1, zone2, and zone3 each have two pods respectively corresponding to two OBServer nodes, the values of READY are all 2/2, and the values of STATUS are all Running, indicating that the scale-out is successful.