Author: Danilo Chiacchio

How to Restore NSX Manager from Backup is an article that explains the process of restoring the NSX Manager from a valid backup. Backup… Backup… Backup… this is an important subject that always we are talking about. In a practical way, few people really are careful about this. For the NSX-T environment, doing NSX Manager backup is mandatory in my opinion. So, if you do not make regular backups of your NSX Manager cluster, please, stop now and do it now! There are a lot of Internet articles about how to configure NSX Manager backup. Also, we have an article…

NSX Distributed Firewall Challenge Scenario shows a scenario with a connectivity issue between two VMs placed on the same segment. The challenge here is to understand the issue by using troubleshooting techniques and fix the issue. Let’s talk a little about the scenario: What is the issue? From the VM “sa-infosec-03” the curl command failed. The curl command is using the reach a web page provided by the “sa-tlsvm-01” VM. Our aim here is to troubleshoot and solve the issue! Note: There are some ways to troubleshoot this issue. So, based on this, we will show a couple of ways…

An MTU change can appear simple, but in a VMware environment it affects multiple layers of the network path. A mismatch between a VMkernel adapter, a vSphere Distributed Switch, and the physical network can interrupt management, storage, vMotion, or vSAN communication. I encountered this situation while helping troubleshoot a four-node vSAN cluster. The environment originally used Jumbo Frames, but the MTU was changed from 9000 to 1500 on parts of the network while several VMkernel interfaces remained configured with MTU 9000. The resulting mismatch disrupted vSAN communication and made the vCenter Server and affected virtual machines inaccessible. In this article,…

Creating an Ansible DNS playbook is a practical way to automate DNS client configuration across multiple Linux servers. Maintaining consistent DNS settings helps ensure reliable network communication and simplifies administration in environments with many managed hosts. On Red Hat Enterprise Linux systems, NetworkManager is responsible for managing network connections and can dynamically update DNS settings in the /etc/resolv.conf file. By using Ansible, administrators can define the desired DNS configuration and apply it consistently across all managed nodes. In this guide, we will create an Ansible playbook to configure DNS settings through NetworkManager. You will learn how to build the inventory,…

Changing the Fully Qualified Domain Name of a vCenter Server is more than changing the Linux hostname of the appliance. The vCenter FQDN is associated with its Primary Network Identifier (PNID) and is used by several internal services, certificates, identity components, and external integrations. In this lab, I changed the vCenter Server FQDN from: to: using the supported vCenter Server Appliance Management Interface (VAMI) workflow. I also validated DNS, certificates, ESXi connectivity, vCenter services, and the environment with the VCF Diagnostic Tool for vSphere (VDT) after the change. Important: All steps in this article were performed in a lab environment.…

Slurm nodes and partitions are among the first components I check when monitoring or troubleshooting an HPC cluster. The sinfo command is one of the first tools I use to understand the current state of a Slurm cluster. It provides a quick view of partitions, compute nodes, node states, time limits, and unavailable resources. In this guide, I will show how to read the default sinfo output, switch to a node-oriented view, identify unavailable nodes, and display the reason associated with DOWN, DRAINED, or similar states. If you want to build an environment where these commands can be tested, see…