NPX – Design Exercise (Nutanix Design)

The NPX Design Review (NDR) has a 60 minute “Design Exercise” where the NDR Examiners present a design scenario with a set of business requirements and constraints that you need to address.  This post is an enhancement of the design strategy I developed for VCDX and tailored for NPX and Nutanix XCP design.

The NDR Examiners are playing the role of a “customer”, with minimal training and knowledge of the platform, and the NPX candidate is the “expert” driving the logical design for the solution.

This post is written with an ESXi and AHV focus (clearly understand what AHV is capable of), Hyper-V is not covered at all.

The NPX Link-O-Rama is a great resource for all things NPX, including this applicable list of articles in my VCDX Deep-Dive series (more than 70 posts).

Some initial pointers:

  • Segment the whiteboard into a template (Requirements, Constraints, Assumptions, Risks, Compute, Network, Storage, VM, VIM, Backup/Recovery, BC/DR, Security).
  • This exercise only requires you to deliver a LOGICAL design, not PHYSICAL. So ignore steps 4 and 5 of the diagram below.
  • Do not waste time on PHYSICAL components unless specifically asked to.
  • This strategy gives you 10 minutes of time to earn extra points with additional questions.
  • The Examiners want you to succeed, listen carefully to their responses for clues and hints.
  • React to their answers if something does not make sense.
  • Each scenario has additional hidden bonus points; the panelists are following a script where you need to ferret out the information by asking the correct questions.
  • Start with the silo you are most comfortable with after the Conceptual Model (assuming it is a deliverable for the scenario), this will get you started and then give you a chance to warm up.
  • Make sure you deliver whatever is requested in the scenario slides.
  • Try to post three logical design decisions in each area.
  • Speak out loud, you cannot score points if you are silent.
  • Sixty minutes is not enough time to build any kind of complete design, you just need to demonstrate your ability to extract information from the customer and begin the process of laying the foundation.
  • Be mindful of the 60 minute timer, stick to your strategy and be wary of the “Rabbit Hole” – do not get stuck in one section, spinning your wheels, asking questions that do not advance and improve your position.
  • Practice, practice, practice.  This is an important part of the defence, you should have mocked this scenario with your Study Group at least 6 times before D-Day.  Practice standing whilst presenting with the NPX timer running on a tablet.


Conceptual Model – Possible Questions: (1-10min)

  • What are the Examiners asking you to deliver? Complete these deliverables first.
  • What is the Design Objective?
  • What are the Requirements, Constraints & Assumptions?
  • What is the Budget?
  • What equipment do you have allocated to this project? Do you have existing XCP infrastructure/licences? If yes, can it be used for this project?
  • Does the customer have an existing Enterprise Architecture that can provide an architectural framework and guidance?
  • Is there a long-term strategy for this project?
  • What is the availability of the design?
  • Is it a multi-site solution with BC/DR?  If yes, how does the SLA translate to RPO, WRT, RTO and MTD?
  • NOTE: Clearly understand the impact of Recoverability upon Availability.
  • NOTE: Here is an exhaustive list of ESXi and AHV design considerations with Nutanix.

Compute (11-20min)

My previous blog post on Sizing a Nutanix Cluster covers this in detail.  Other possible questions to consider:

  • PCIe/USB dongles required as part of the P2V process that will invalidate the use of Nutanix infrastructure?
  • Make sure you account for VM overhead, CVM sizing and Hypervisor overhead in your calculations.
  • Right-Size VMs after conversion? How?

Storage (21-30min)

Possible questions to consider:

  • V2V from an existing Non-Nutanix Cluster with FC, FCoE, iSCSI, NFS or VSAN?  What would the migration plan be?
  • Understand Controller VM Sizing
  • Tiers of Storage? Hybrid or Flash Nodes? Limits of Nutanix clusters?
  • Peak IOPS, IO sizes, etc.
  • Possible Calculation 1 – Peak storage capacity required?
  • Possible Calculation 2 – Peak IOPS required?
  • Possible Calculation 3 – Average IO Size?
  • Possible Calculation 4 – Read/Write Ratios?
  • Possible Calculation 5 – Active Working Set per Node?  (What are the possible methods for calculating this?)
  • Storage Pools, Containers, Replication Factor, Deduplication, Compression, Erasure Coding, Acropolis Volumes API?

Network (31min-40min)

Possible questions to consider:

  • Traditional, Collapsed Core or Clos-type (Leaf and Spine) Switch Architecture?
  • Traffic flows: North/South or East/West?
  • ESXi: VDS/VSS/Cisco Nexus 1000V?
  • ESXi: Hybrid or VDS only? NIOC?
  • AHV: IPAM, Number of Bridges, mixed speeds per bond, load balancing mechanism?
  • 1GE or 10GE?
  • Possible calculation: What is the peak network throughput required (north/south and east/west)?

Example Network Logical Design Deliverable (AHV):


Virtual Infrastructure Management (Availability & Datacenter) (41-50min)

Possible questions to consider (may have covered some of this in the Compute section):

  • ESXi: vSphere HA/DRS? Limits?
  • ESXi: Dedicated management cluster, virtual vCenter, vCSA?
  • ESXi: vSphere Licences?
  • ESXi: vCenter Design?
  • ESXi: vROPs?
  • REST API integration with Cloud Management Platform?
  • Upgrade process for AOS, Hypervisor and Firmware?
  • Prism Central?
  • Nutanix licences?

Additional Areas (51-60min)

You may have time to ask about:

  • VM design – ParaVirtual drivers, OS types, VM Tools, etc.
  • Security – AV, Firewalls, Compliance/Governance, etc.
  • Backup/Restore
  • BC/DR
  • Web-Scale Migration Plan

Additional Resources:


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Chief Enterprise Architect and Strategist, 4xVCDX#133, NPX#8, DECM-EA.