In Nutanix, a cluster with RF2 (Redundancy Factor 2) can tolerate the failure of a single node or drive1. However, to ensure that the cluster can survive a complete rack failure without negatively affecting workload performance, we need to consider rack awareness. When rack fault tolerance is enabled, the cluster has rack awareness and the guest VMs can continue to run with failure of one rack (RF2) or two racks (RF3). The redundant copies of guest VM data and metadata exist on other racks when one rack fails2.

Given the current cluster configuration (30 nodes distributed 10 nodes per rack across three 42U racks), adding 3 additional nodes per rack (9 nodes total) would increase the redundancy of the cluster and improve its ability to withstand a complete rack failure. This is because the additional nodes would provide more storage capacity and compute resources, allowing the cluster to continue running workloads even if one rack fails.

References:

Understanding Fault Domains and Rack Awareness | Nutanix Community

RF2 -> RF3 | Requirements | Nutanix Community