At some point in the future, one or more AKS-HCI workload clusters may begin to saturate the ASHCLUSTER resources like processor, memory, and storage. We primarily use Windows Admin Center to monitor the resource utilization at this layer. If we must expand the Azure Stack HCI cluster, we can use the Dell EMC OpenManage Integration with Microsoft Windows Admin Center cluster expansion feature. This feature helps simplify the cluster expansion process by preparing new cluster nodes before adding them to the cluster. 

This preparation includes the following checks:

• High-level compatibility checks – Enforces strict rules and only allows the administrator to proceed with compatible AX nodes from Dell Technologies.
• License check – Validates that the existing cluster nodes and new nodes have the Dell EMC OpenManage Integration for Microsoft Windows Admin Center  Premium License for Microsoft HCI Solutions from Dell Technologies installed.
• HCI Configuration Profile check – Verifies that best practices have been followed in the configuration of the cluster. This checks infrastructure symmetry, allowed drive types, and Storage Spaces Direct cache percent. 
• Compliance reporting and remediation – BIOS, firmware, and drivers are updated with the Azure Stack HCI solution catalog on the new AX nodes. Existing cluster nodes are updated with the Cluster-Aware Updating feature in the stand-alone extension.  

In the lab, we did not have a fifth AX-740xd node available to expand our cluster. However, we tested the process on another cluster, bdc-ax6515clu.test.lab, which was running three AX-6515 nodes. Before attempting to add one more node to the cluster, we completed the following tasks:

• Installed the Azure Stack HCI 20H2 operating system and changed the hostname to ax6515rn3.
• Configured basic settings such as networking and administrator credentials. We also joined the new host to the same domain as the existing cluster.
• Added the node to Windows Admin Center.
• Ensured that cluster administrators could access the new node with local administrator privileges. 

The following figure shows the first step in the workflow, which involved the high-level compatibility, license availability, and HCI Configuration Profile checks. 

Figure 35.    Expand cluster completed checks

The following figure shows the tests performed during the HCI Configuration Profile check.

Figure 36.    Dell EMC HCI Configuration Profile tests

We generated a compliance report comparing the BIOS, firmware, and driver levels with the Dell Technologies solution catalog validated for Azure Stack HCI. The following figure shows that the existing bdc-ax6515clu cluster nodes were fully compliant with the offline solution catalog. However, the new ax6515rn3 node was non-compliant. 

Figure 37.    New node showing not compliant

We reviewed which components required updating by clicking View Details. To remediate the non-compliant components, we clicked Finish.  

Figure 38.    Remediation successful on new node

We were confident that the ax6515rn3 node could be added to the cluster. The remaining steps to add the node to the cluster were found in the HCI Operations Guide (under Expanding the Azure Stack HCI cluster). Many variables can affect the time that is required to perform this expansion procedure:

• Number of nodes being added to the cluster
• Hardware configuration of the new nodes
• Number of VMs running on the current cluster
• Types of workloads running in the VMs
• Number and type of BIOS, firmware, and driver updates to be applied 
• Network configuration

Note: To go through the Cluster Expansion process,  see the Interactive Demo: OpenManage Integrations with Microsoft Windows Admin Center.