Initial two-pod deployment consists of one cluster for the Management pod and another cluster for the collapsed Edge / Resource pod. Clusters are vSphere objects for pooling virtual domain resources and managing resource allocation. Clusters scale up as needed by adding ESXi hosts, while pods scale up by adding new clusters to the existing pods. This design ensures that management boundaries are clearly defined, capacity is managed, and resources are allocated based on the functionality hosted by the pod. vCloud NFV VIM components allow for fine grained allocation and partitioning of resources to the workloads, regardless of the scaling method used.
As best practice, begin the initial deployment with a minimum of four hosts per cluster within each pod, for a total of eight hosts. With initial four-host cluster deployment, a high degree of resiliency is enabled using vSAN storage. At the same time, four hosts allow placing cluster management components such as vCenter Server active node, standby node, and witness node on separate hosts in the Management pod, creating a highly available Management pod design.
The initial number and sizing of management components in the Management pod are pre-planned. As a result, the capacity requirement of the Management pod is expected to remain steady. Considerations when planning Management pod storage capacity must include operational headroom for VNF files, snapshots, backups, virtual machine templates, operating system images, and log files.
The collapsed edge / resource cluster sizing will change based on the VNF and networking requirements. When planning for the capacity of the Edge / Resource pod, tenants must work with the VNF vendors to gather requirements for the VNF service to be deployed. Such information is typically available from the VNF vendors in the form of deployment guides and sizing guidelines. These guidelines are directly related to the scale of the VNF service, for example to the number of subscribers to be supported. In addition, the capacity utilization of ESGs must be taken into consideration, especially when more instances of ESGs are deployed to scale up as the number of VNFs increases.
When scaling up the Edge / Resource pod by adding hosts to the cluster, newly added resources are automatically pooled, resulting in added capacity to the PvDC. New tenants can be provisioned to consume resources from the total available pooled capacity. Allocation settings for existing tenants must be modified before they can benefit from increased resource availability. Tenant administrators can then fine tune the resource allocation of their OvDCs and allocate resources to the VNF workloads.
New clusters are added to a PvDC to scale out the Edge / Resource pod. The CSP can migrate existing VNF workloads from the initial cluster to the newly added cluster to ensure ESG capacity availability. Due to leaf-and-spine network design, additional ESGs in the new cluster will continue to be deployed in the initial cluster.