It is of prime importance to make sure that every ESXi host in a cluster is configured identically to achieve operational efficiency at the cluster level. There is a lot of configuration that would go into an ESXi host after it is deployed. These include the general/advanced settings, storage, and networking configuration, licensing, and so on. With the number of ESXi hosts that can be part of a cluster or vCenter increasing with every release of vSphere, the amount of work to be done manually will also increase.
Starting with vSphere 4.1, VMware introduced a method to extract the configuration from an ESXi host and form a configuration template, often referred to as a blueprint or golden image. Such a configuration template is called a vSphere Host Profile. It is important to note that Host Profiles require Enterprise Plus Licenses applied.
Host Profiles help an administrator to maintain compliance with configuration standards on a set of ESXi hosts. They can also be used to make a configuration change to be pushed to all the hosts attached to the template, without the need to make the change on each of the hosts manually. For instance, if the NTP time source for the environment has changed, then there is a need to make this change on every host using the time source. Such a change can be pushed through a Host Profile. Another example would be a change in the VLAN ID for the virtual machine network on a cluster of ESXi hosts configured with standard vSwitches. Since the hosts are using standard vSwitches, the VLAN ID should be manually specified on the virtual machine port group on each of the hosts in the cluster. This manual work can be avoided by editing the Host Profile and then pushing the VLAN ID change to the entire cluster.
So, what does a Host Profile look like, and what does it contain? Host Profiles, once created, are presented to the user as GUI objects in the vCenter Server. Host Profiles contain configuration policies that are either fetched from the reference host or added to the Host Profile at a later stage.
A Host Profile can contain the following information:
- Advanced configuration settings
- General system settings
- Networking configuration
- Security and services
- Storage configuration