About Host Groups
You can create custom groups of virtual machine hosts, known as host groups, for ease of monitoring and management of hosts and virtual machines. Host groups are represented by folders in the navigation pane of Hosts view and Virtual Machines view. Host groups are created by using the New host group action in both of those views.
How Should I Use Host Groups?
A host group's most basic function is as a container that you can use to group hosts and the virtual machines on those hosts in a meaningful way in Hosts view and Virtual Machines view. You can also use host groups to set aside resources on the hosts for the use of the host operating system, to provide hosts for self-service users, and to enable automatic placement of virtual machines on the best host in a group of hosts.
You can create host groups to organize hosts in whatever manner makes sense for your environment:
- Basic organization when managing large numbers of hosts and virtual machines—Use host groups to create custom views within Hosts view and Virtual Machines view to provide fast monitoring and access to host groupings of your choice. For example, you might create a host group for each branch office in your organization.
- Scoping administrative tasks such as the placement of virtual machines on hosts—You can limit the hosts examined for an administrative task by creating a host group. For example, restrict the placement of a virtual machine by selecting a particular host group.
- Reserving resources for use by hosts—Host reserves come into play when virtual machines are placed on a host. The host reserves determine the amount of CPU, memory, disk space, disk I/O capacity, and network capacity that will always be available to the host operating system. Use the Host group properties action for the root host group, All Hosts, to set default host reserves for all hosts managed by Virtual Machine Manager. If you want to use the resources on some hosts more fully than on others, you can set host reserves for other host groups.
- Automatically placing virtual machines on the most suitable host—In Virtual Machines view, you can drag a virtual machine to a host group to automatically place the virtual machine on the most suitable host in a host group. Automatic placement is also used to deploy the virtual machines that users create in virtual machine self-service. For more information, see About Virtual Machine Placement.
- Providing hosts on which users can create and operate their own virtual machines—This feature is known as virtual machine self-service. The administrator adds self-service policies to a host group to allow users or groups to create, operate, and manage their own virtual machines within a controlled environment on the hosts in the host group. For more information, see About Virtual Machine Self-Service.
Creating a Host Group Hierarchy
Host groups are hierarchical. You can create a child host group of an existing host group for general management purposes, to override host reserves inherited from a parent host group, or to amend or add to the virtual machine permissions inherited from the self-service policies of a parent host group.
All host groups and all hosts belong to the root host group, All Hosts, which is created during installation and is represented by the top node in Hosts view and Virtual Machines view.
Each host or host group is identified by its host path, a sequence of host group names that specifies the location of a host or host group within the hierarchy of host groups in the navigation pane. All host paths begin with the root host group. For example, the host path All Hosts\New York\Site21\VMHost05 indicates that the host VMHost05 belongs to the host group Site21, which is a child host group of the host group New York.
Inheritance of Host Group Properties
Child host groups can inherit host reserve settings and self-service policies from their parent host groups. However, property inheritance works differently for these two features:
Host reserves—When you change the host reserves for a parent host group, you can choose whether or not to cascade the host reserve settings to hosts in all of its child host groups. If you choose to cascade the host reserve settings, all of the host reserve settings for the parent host group overwrite all previous settings for all hosts in all of the child host groups of the parent host group.
Note
When you cascade host reserve settings to child host groups, the changes to the child host groups are not audited on the Change Tracking tab in the job details.
Self-service policies—If a parent host group is used for virtual machine self-service, each of its child host groups automatically inherits self-service policies from the parent host group. However, you can add a self-service policy for the same user or group to both a parent host group and its child host group. By adding policies to both parent and child, you can assign the same users different templates, set different virtual machine permissions, and assign a different virtual machine quota on a subset of hosts within the parent host group. For more information about self-service policy inheritance, see About Self-Service Policies.
See Also
Concepts
About Self-Service Policies
About Virtual Machine Placement
About Virtual Machine Self-Service
Host Groups