To determine the best configuration, we need to calculate the required storage, including the additional 20% growth and the capacity to re-protect in the event of a node failure:
* Initial Storage Requirement:
* Usable storage required: 15 TiB
* Additional storage for 20% growth: 15×0.2=3 TiB15 \times 0.2 = 3 \text{ TiB}15×0.2=3 TiB
* Total storage required: 15+3=18 TiB15 + 3 = 18 \text{ TiB}15+3=18 TiB
* Storage with Re-protection:
* To ensure data protection and availability, Nutanix typically uses a replication factor (RF) of 2, meaning each piece of data is stored twice.
* Therefore, the total raw storage needed: 18 TiB×2=36 TiB18 \text{ TiB} \times 2 = 36 \text{ TiB}18 TiB×2=36 TiB Given these calculations, we should look for a configuration that provides at least 36 TiB of raw storage.
Based on typical Nutanix node configurations, Option D provides the best balance of cost and capacity, ensuring that the requirement for 36 TiB of raw storage is met.

To ensure that an RF2 (Replication Factor 2) cluster can survive a complete rack failure without negatively affecting workload performance, it is important to have sufficient nodes distributed across multiple racks to maintain data availability and redundancy.
* Current Cluster Configuration:
* 30 nodes distributed as 10 nodes per rack across three racks.
* 40TB usable storage per node (total 1.2 PB).
* Current utilization: 900TB.
* Surviving a Complete Rack Failure:
* With RF2, data is replicated to two nodes. To survive a complete rack failure, each rack should have enough nodes to ensure that data can be replicated across the remaining racks.
* Adding 3 additional nodes per rack (total 9 nodes) ensures that the cluster can still function with
27 nodes across three racks, maintaining redundancy and performance.
* Avoiding Single Points of Failure:
* Ensuring that each rack has a balanced number of nodes helps avoid single points of failure and ensures that workloads can continue to operate without performance degradation.
By expanding the cluster to 39 nodes (13 nodes per rack), the administrator ensures that the cluster can handle a complete rack failure while maintaining sufficient storage capacity and performance.
References:
* Nutanix Bible, Cluster Resiliency and RF2 Configurations.
* Nutanix-NDB-User-Guide, Guidelines for Adding Nodes to a Cluster.

For a prospect interested in evaluating Nutanix at no cost for a few months using existing test hardware:
* Requirement Analysis:
* The prospect wants a free evaluation.
* They intend to use their existing hardware.
* Their focus is on experiencing platform management rather than performance.
* Feature Analysis:
* Nutanix NX POC: Provides a proof of concept using Nutanix hardware, which might not align with the prospect's desire to use existing hardware.
* Nutanix Community Edition (CE): A free, fully functional version of Nutanix AOS that can be installed on existing hardware. It is intended for non-production use and allows users to
* experience the management features of Nutanix.
* Nutanix Go: A subscription-based service providing Nutanix hardware and software, not suitable for a no-cost evaluation.
* Nutanix Test Drive: Offers a short-term, hands-on experience in a hosted environment, but does not allow for an extended evaluation using the prospect's hardware.
* Conclusion: Nutanix Community Edition is the best option for the prospect as it allows a no-cost, extended evaluation using their existing hardware and focuses on platform management capabilities.
References:
* Nutanix Community Edition documentation

B: Defined and measurable success criteria:
* Before proceeding with a Proof of Concept (POC), it is crucial to establish defined and measurable success criteria. This ensures that both the SE and the prospect have a clear understanding of what constitutes a successful evaluation.
* Success criteria provide a benchmark to measure the performance, functionality, and benefits of Nutanix in the prospect's environment. It helps in objectively assessing the POC outcomes and making an informed decision.
* Without clear success criteria, the POC could lack direction, and the results might be open to interpretation, leading to potential disagreements and an inconclusive evaluation.