Nutanix capacity planning includes a feature called “Reserve Capacity for Failure,” which ensures that enough resources are preserved to sustain one or more node failures without impacting cluster functionality.

For RF3 clusters, the documentation states:

“Reserve Capacity for Failure should be set to Auto Detect, which calculates the required resources dynamically based on node count, RF policy, and data distribution.”

RF3 requires more resiliency than RF2, and manual settings such as fixed percentages do not accurately reflect the space needed during multi-node failure resiliency. “None” is never recommended because it eliminates failover protection. Memory reserve percentages do not impact storage resiliency. Storage reserve percentages are static and do not reflect the real RF3 overhead.

Auto Detect ensures Nutanix automatically calculates the resources needed to sustain the required failure domains.