Adding compute nodes to an existing Red Hat OpenShift Container Platform installation

As more Maximo® Application Suite applications are deployed or as the workload increases, it might be necessary to provision more compute nodes.

The following are good indicators that it is time to add more compute nodes to the cluster:
  • Pods cannot be scheduled due to insufficient CPU.
  • Pods cannot be scheduled due to insufficient memory.
  • Pods are evicted due to disk pressure on compute nodes.

The following instructions show how to add an extra compute node to the existing Red Hat® OpenShift® Container Platform (OCP) cluster.

Procedure

  1. Add a DNS entry for the new compute node. In the DNS example, add the DNS entry for the new compute node to the /var/named/cluster1.example-cluster.com.hosts and /var/named/172.28.70.rev files on the bastion host.
  2. Restart the DNS server by running the following command: 
    
systemctl restart named
  3. Add a DHCP entry for the new compute node. In the DHCP example, add the DHCP entry for the new compute node to the /etc/dhcp/dhcpd.conf file on the bastion host.
  4. Restart the DHCP server by running the following command: 
    
systemctl restart dhcpd
  5. Follow the steps in Provisioning VMs on VSphere to provision a new VM on VSphere for the new compute node.
  6. Power on the new compute node VM and select install worker in the PXE boot screen. Wait for RHCOS to finish installing on the new compute node.
  7. From the bastion host, run the following command to approve the pending CSRs for the compute node. 
    
oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve