What is the minimum cluster size for Redundancy Factor 3?

Redundancy Factor 3 (RF3) ensures that three copies of all data are maintained across different nodes within the Nutanix cluster. This configuration provides high availability by allowing the cluster to tolerate the simultaneous failure of up to two nodes without data loss or service interruption. To guarantee that each of the three data copies can be placed on a unique node, a minimum of five nodes is required in the cluster. This is a fundamental architectural requirement for the Nutanix Distributed Storage Fabric (DSF).

A. 3 nodes: This is the minimum cluster size required for Redundancy Factor 2 (RF2), which maintains two data copies and can tolerate the failure of a single node.

B. 4 nodes: A four-node cluster does not have enough nodes to satisfy the unique-node placement requirement for three data copies needed for Redundancy Factor 3.

D. 6 nodes: While a six-node cluster can support Redundancy Factor 3, it is not the minimum required size. The question specifically asks for the minimum.

1. Nutanix University. (2023). Nutanix Hybrid Cloud Fundamentals v6.5 Student Guide. Module 4: Data Protection and Disaster Recovery, "Redundancy Factor" section. The courseware explicitly states, "Redundancy Factor 3 (RF3) requires a minimum of five nodes and protects against two concurrent node or disk failures."

2. Nutanix. (2023). Prism Web Console Guide, AOS 6.7. Data Protection and Recovery > Data Resiliency in a Cluster > Resiliency Status. The documentation notes, "For redundancy factor 3, you must have at least five nodes in the cluster."

3. Nutanix. (2023). Data Protection and Recovery with Acropolis, BP-2033. Section: Failure and Recovery Scenarios, Subsection: Redundancy Factor. This best practices guide details, "Redundancy factor 3 (RF3) requires a minimum of five nodes. With RF3, the cluster can tolerate two simultaneous node failures."