How do you “Resolve” NSX Cluster Preparation Error Programmatically ?

The preparation of a vSphere cluster to support VXLAN is divided into two steps:

  • Install where the NSX manager pushes the hypervisor kernel modules to the cluster’s ESXi hosts.
  • Configure where you creates the VXLAN vmknic interfaces, provide Segment ID or VNI & defines transport zone

NSX for vSphere installs three vSphere Installation Bundles (VIB) to the host that enable NSX functionality. One VIB enables the layer 2 VXLAN functionality and another VIB enables the distributed router, while the final VIB enables the distributed firewall. After adding the VIBs to a distributed switch that distributed switch is then referred to as an VMware NSX Virtual Switch. On an NSX Virtual Switch, the hosts are not restricted to being on the same layer 2 domain for virtual machine to virtual machine communication across hosts.

Kernel Modules

From the NSX Home Screen -> Installation -> Host Preparation screen, click the Install link to prepare all available clusters. This deploys all required kernel modules and user space tools needed for NSX for vSphere.


However, not always it goes smooth as expected. In some cases the Installation Status may report Not Ready Resolve.


If this happens, click on “Not Ready” and read the message. Then click “Resolve” to resolve the problem. Click yes to “Are you sure…” and note “Installing” and “In Progress” on the ESXi servers.

However, many a times clicking it manually is not an option specially when its a purely automated environment and also when large scale deployment happens. VMware has provided API to just press that Resolve link. Either you can use REST Client to send the HTTP body or you can combine it with another scripting language such as VMware PowerCLI. Here my friend Timo Sugliani has written a cool code to click on that Resolve button to fix the issue with cluster preparation. Click on the above link and download the script and run it in your environment to fix the resolve issue programmatically.


About Prasenjit Sarkar

Prasenjit Sarkar is a Product Manager at Oracle for their Public Cloud with primary focus on Cloud Strategy, Cloud Native Applications and API Platform. His primary focus is driving Oracle’s Cloud Computing business with commercial and public sector customers; helping to shape and deliver on a strategy to build broad use of Oracle’s Infrastructure as a Service (IaaS) offerings such as Compute, Storage, Network & Database as a Service. He is also responsible for developing public/private cloud integration strategies, customer’s Cloud Computing architecture vision, future state architectures, and implementable architecture roadmaps in the context of the public, private, and hybrid cloud computing solutions Oracle can offer.

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