When a virtual machine is deployed on a host, the process of selecting the most suitable host for the virtual machine is known as virtual machine placement, or simply placement. During placement, hosts are rated based on the virtual machine’s hardware and resource requirements, the anticipated usage of resources, and capabilities resulting from the specific virtualization platform. Host ratings also take into consideration the placement goal: resource maximization on individual hosts, load balancing among hosts, or whether the virtual machine is highly available. The administrator selects a host for the virtual machine based on the host ratings.
In the following cases, a virtual machine is automatically placed on the most suitable host in a host group, in a process known as automatic placement:
- In virtual machine self-service, users'
virtual machines are automatically placed on the most suitable host
in the host group that is used for self-service.
- Automatic placement also occurs when the
drag-and-drop method is used to migrate a virtual machine to a host
group in Virtual Machines view.
During automatic placement, the configuration files for the virtual machine are moved to the volume judged most suitable on the selected host. For automatic placement to succeed, a virtual machine path must be configured on the recommended volume. For more information, see About Default Virtual Machine Paths.
|If you configured a virtual machine with the hardware configuration: Make this VM highly available, only clustered Hyper-V hosts and ESX hosts in a host cluster can be rated highly. For more information, see How to Configure Virtual Machine Priority and Availability.|
Customizing Host Ratings
The metrics for rating hosts can be customized for Virtual Machine Manager. For information, see How to Set Placement Defaults for Virtual Machines. Host ratings also can be customized for individual virtual machines during deployment or migration. For more information, see How to Customize Host Ratings for a Virtual Machine.
Removing a Host from Placement
You might want to use some hosts only for maintenance tasks such as creating and patching virtual machines. To aid in this, you can designate a host a maintenance host or you can remove the host from placement. This is done by updating the properties of the host. For more information, see How to Set Placement Defaults for Virtual Machines.
For the most up-to-date Help information, go to the Virtual Machine Manager 2008 Help Online. To find additional Virtual Machine Manager 2008 documentation, go to the Virtual Machine Manager 2008 TechCenter Library.