AMD Zen4/Zen5 processors have been known to have slower entropy generation, which can lead to higher CPU utilization for workloads that depend on random number generation. I recently learned from a colleague (Ross Wynne) about a simple optimization for NSX Manager that can significantly reduce CPU utilization when running on AMD Zen4/Zen5 processors.

Shut down your NSX Manager VM and add the following VM Advanced Setting. This allows the guest operating system to retrieve entropy directly from the ESXi host, which already includes optimizations for entropy generation on AMD Zen4 and Zen5 processors.

isolation.tools.getEntropy.disable = FALSE

Note: Ensure you have applied the recommended entropySource configuration for your physical ESX host in addition to this configuration change.

In my limited testing, I have observed the NSX Manager load average drop to less than 5, whereas it was consistently much higher before applying this optimization. I will continue to monitor my environment, but this is definitely a worthwhile optimization to add to your VCF homelab toolkit. This configuration change can also benefit NSX Edge and NSX Virtual Network Appliances (VNA).

Before deploying a new VMware Cloud Foundation (VCF) 9.0 environment, the VCF Installer performs a number of validations including network MTU. The minimum MTU that is required to deploy VCF is 1600, which is used for the Tunnel Endpoint (TEP) for NSX traffic between your ESX hosts.

For most environments, this is not an issue and users will typically deploy VCF with Jumbo Frames enabled and configure the MTU with value of 9000. If your environment does not meet the minimum MTU requirement, the VCF Installer will flag this as an error and prevent you from deploying as shown in the screenshot below.

If you can not meet the MTU requirement, you can bypass the validation check so that you can continue with your deployment of the VCF Management Domain.

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As I continue my VMware Cloud Foundation (VCF) 9.0.2 upgrade journey, I have now reached the core SDDC components, including vCenter, NSX, and ESX.

NSX Manager and NSX Edges was up first and before the upgrade begins, a pre-check is performed. I was not expecting any issues but to my surprise, I ran into the following validation error:

DNS is not configured on edge 83ea6662-41b2-48aa-a8d0-22039d3230c0. Edge will not be able to resolve the fqdn to download the upgrade bundle from NSX manager. Kindly configure a valid DNS on edge.. Other components that failed with the same error: edge01b, edge01a

We all know how important DNS is and ensuring it is configured correctly, both forward and reverse lookups.

However, I like to think that I am pretty good about ensuring everything in my lab is setup with DNS and this honestly was a surprising error, that BOTH NSX Edges do NOT have DNS configured!?! 🤔

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