Scalability involves two types of environments: VMware Cloud Foundation (VCF) and non-VCF environment where we use VMware Validated Foundation. With VCF we have significant automation built-in within the VCF console within SDDC manager as the primary management console. For non-VCF environments, it depends on customer choice. For small environments, we do manual scalability and sometimes use Terraform scripts to keep the host ready and add in the cluster automatically. For large environments with frequent scalability actions, we propose the Terraform solution that builds ESXi, does necessary configuration, and automatically starts up for associating with the existing environment. If scaling is infrequent, with one or two hosts per month, it is a manual job. From a challenge perspective, it seems easier, with just a few pre-checks regarding make and model compatibility, disks, and server health on the hardware level.
