An Evaluation of the vSphere Diagnostic Tool

September 28, 2022
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Conrad Ramos, Technical Architect, GCSIT
vSphere diagnostic tool - VMware Flings

The vSphere Diagnostic tool has been released for a while at this point, and I thought it might be helpful to run a quick evaluation of this Fling and determine it’s usefulness in the day-to-day management of a vSphere environment.

The first thing to know about this Fling is... it is a Fling. Flings are tools and apps created by VMware Engineers as side projects. These side projects occasionally get released to the public, however it is important to note that these Flings are not supported by VMware. So, if you cannot get a Fling configured, or if a Fling negatively affects a vSphere environment, don’t expect VMware to help.

The vSphere Diagnostic Tool is basically a python script which runs on your vCenter directly and returns general health and diagnostic information about the vCenter. Let us examine how to get it set up.

After downloading the tool from the fling page, we need to get the zip file to the vCenter. The easiest way is to use SCP to send the file to the vCenter.

After connecting to the vCenter via SSH run the following command to enable SCP

Image of commands to enable SCP

Once SCP is enabled, send the zip file to the vCenter server, via an SCP client. In this instance I used WinSCP:

I sent the file to the /tmp directory, but the user home directory also works as well.

Next I disable SCP, as we will not need it anymore:

Now we just need to unzip the fling and run it:

After prompting for credentials, the first information we see is basic information for the vCenter:

Nothing really exciting here as most of this information should already be known by the administrator.

Next up is the DNS information:

As with most infrastructure components, DNS is critical to everything running correctly. Knowing there are no issues(currently) with DNS can allow any troubleshooting to progress to other areas of concern.

The script next looks at the various services which require certificates and validates that everything looks good. I am not including all the services here, as just a few give a good impression of the rest.

The only issue seen is NTP, however as mentioned, this is a lab environment, and NTP is not currently configured correctly. The remaining checks are fairly self-explanatory, and they all look to be in a good condition.

I do see some value in utilizing the vSphere Diagnostic Tool if there are some issues with a vCenter or if in an environment that we know to be the intended audience. It could also be helpful if you are becoming responsible for a new environment, and you need to do an initial check to make sure there are no glaring errors or issues. On the day-to-day management of vCenter though, I don't see any reason to run this tool on a regular basis. In most cases, vCenter itself will alert you if there are issues with itself, and the VAMI itself normally provides a nice "at a glance" view to inform you of any configuration issues or errors that need to be addressed.

A few people have recommended the vSphere Diagnostic Tool as a sort of health check. In my opinion, it is better served as its name implies, as a diagnostic tool. In bigger environments of multiple vCenters, it simply doesn't make sense to individually log in to every vCenter and run this tool on a regular basis. On the other hand, proactively having a tool like this in place and ready when needed is never a bad thing.

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