Host baseline groups are useful when you have to perform an upgrade. Also, post upgrade, you may need to install patches that were released at a later date than the host upgrade or an extension (for example, a driver upgrade) that will make the server hardware compatible with the newer upgrade.
It is a requirement that you already have the required ESXi Image imported. Read the recipe Importing ESXi Images for instructions.
The following procedure will help you create a host baseline group:
Connect to vCenter Server as an administrator using the vSphere Client.
Go to Home | Update Manager.
Navigate to the Baselines and Groups tab and click on the Create link corresponding to the baseline groups.
In the New Baseline Group wizard, select the baseline group type as Host Baseline Group, supply a name for the baseline group, and click on Next to continue, as shown in the following screenshot:
Choose an existing host upgrade baseline with the correct image...