To configure Replication Factor 1 (RF1), the cluster must have at least three nodes. In RF1, data is replicated to two other nodes within the cluster, so having at least three nodes is necessary to ensure that the data is replicated. Moreover, when you configure RF1, the cluster must have a minimum of three nodes to ensure that the data is accessible even if one of the nodes goes down. Reference: https://portal.nutanix.com/page/documents/details?targetId=Prism-Admin-Guide-v5_6:pr-data-protection-replication-factor-c.html

ADS is a feature of Nutanix AHV (Acropolis Hypervisor) that proactively monitors a Nutanix cluster for compute and storage I/O contention or hotspots over a period of time [1]. It provides dynamic and intelligent scheduling of workloads on the cluster for optimal performance and utilization.

Direct Upload is a LCM feature that simplifies upgrades on clusters without Internet access. It allows users to upload the desired version of the software to the cluster using a USB drive or other portable storage device, and then install it without the need to access the Internet. Reference: https://portal.nutanix.com/page/documents/details?targetId=Platform-Administrator-Guide-v5_7:pag-lcm-direct-upload-c.html