ESXi

One of the topics in the VMware vSphere Optimize and Scale course is how the amount of RAM is calculated that your host should have available as a minimum before processes such as ballooning and swapping become active.

The course material provides this table that shows us how this minimal free memory is calculated:

When sizing virtual machines you should be aware of the number of physical cores available in your ESXi-host and whether or not it has Hyper-Threading enabled. If you blindly follow the number of vCPU's you can add that VMware presents to you, then you could end up with VM's that offer poor performance. If you want to understand Hyper-Threading and why this is important for sizing please read the articles that I have listed at the bottom of this page.

In the vSphere Client and vSphere Web Client you can find how many days your host has been running. But what happened before that period? How often did your host boot in the past? This information is stored in the file /var/log/vmksummary.log on your ESXi-host. The file is updated  hourly with information how long your host has been up and how many virtual machines are running at that moment.

When you want to use USB devices in a virtual machine you don't want to connect them to your physical ESXi-host and then from there pass through to a virtual machine. By doing this you pin the virtual machine to the host. For example with a failover the virtual machine would boot on another host and would not be able to connect to it's USB-device, which is still plugged into the failed host. Also with vMotion your options are limited. To solve this problem several solutions have been around to access USB-devices remotely via the network. 

If you are using a Linux-based pc or Mac OS X and want to manage a vSphere-environment then you might ask yourself the question if there is a native OS-version of the vSphere Client available for your platform.

The short answer is: no.