The system elements described in the following topics are common to all CLM deployments.

You can use a disk image to instantiate CLM elements and functions as VMs, as described in Disk-image deployment for CLM.

Note: The RHEL OS image deployment steps in a procedure are specific to a RHEL KVM environment; however, alternative virtualization environments are supported, as described in KVM virtualization.

To deploy a RHEL OS image in an environment other than KVM, you must observe the requirements in OpenStack virtualization or VMware virtualizationfor the environment, and perform the deployment as directed in the virtualization product documentation.

The main elements of a CLM system are the following:

• CLM deployer host; deploys containerization environment for CLM cluster; one CLM deployer host is required in each data center of a DR deployment

• CLM cluster VMs; host the main CLM functions

The CLM deployer host and CLM cluster VM can be hosted on one physical station, or on separate stations. Figure 8-1, CLM deployer host and CLM cluster shows a standalone deployment on one physical station that hosts the CLM deployer host and CLM cluster VM.

Note: Communication between the CLM deployer host and the CLM cluster VM is IPv4-only.

Figure 8-1: CLM deployer host and CLM cluster

CAUTION Service degredation risk

The CLM deployer host is a crucial element of a CLM cluster deployment that must remain reachable by each CLM cluster VM after the initial deployment; otherwise, cluster recovery in the event of a failure may be compromised.

You must ensure that the CLM deployer host remains operational and reachable by the CLM cluster VMs at all times.

The CLM deployer host holds the required container image repository and Helm repository, and pushes a containerization environment for the CLM cluster.

The CLM software runs on the CLM cluster VMs, and is load-balanced among the VMs, depending on the deployment configuration.

CLM cluster host

The CLM cluster host is a specific CLM cluster VM from which CLM configuration operations are performed. The VM requires direct network access to the CLM deployer host.

Note: The CLM cluster host is functionally no different from the other VMs in a CLM cluster; the VM is merely the designated cluster member for performing cluster and software management actions. The designation helps to prevent operator confusion, and simplifies the logging of maintenance actions.