Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
One of the top questions that I keep hearing from our customers is to explain the ‘over-committed’ status and why we sometimes display this status. An example of when this status might be displayed is when attempting to migrate a VM to a particular host, depending on what is already on the destination the ‘over-committed’ status might be displayed.
HAVM Placement and “Over-committed” Status
When placing a highly available virtual machine, the placement process in VMM calculates whether adding a new virtual machine to a host cluster will over-commit the cluster based on the cluster reserve configured for the host cluster in VMM. The cluster reserve specifies the number of node failures a cluster must be able to sustain while still supporting all virtual machines that are currently deployed on the clustered hosts. If a host cluster cannot withstand the specified number of node failures and still keep all of the virtual machines running, the cluster is placed in an Over-committed state, and the hosts are not available for placement. An administrator can override this and place an HAVM on a host in an over-committed cluster during manual placement. Cluster reserves are a unique feature of VMM.
For example, if you specify a node failure reserve of 2 for an 8-node cluster, the rule is applied in the following ways:
· If all 8 nodes of the cluster are functioning, the host cluster is marked Overcommitted if any combination of 6 nodes (8-2) in the cluster lacks the capacity to accommodate existing virtual machines.
· If only 5 nodes in the cluster are functioning, the cluster is marked Overcommitted if any combination of 3 (5-2) nodes in the cluster lacks the capacity to accommodate existing virtual machines.
VMM’s cluster refresher updates the host cluster’s Over-committed status after each of the following events:
· A change in the cluster reserve value
· The failure or removal of nodes from the host cluster
· The addition of nodes to the host cluster
· The discovery of new virtual machines on nodes in the host cluster
The cluster reserve is set on the General tab of the host cluster properties. For a procedure, see How to View and Modify the Properties of a Host Cluster (https://go.microsoft.com/fwlink/?LinkID=162986).
The above information is available in the System Center Virtual Machine Manager 2008 R2 Operations Guide.
Download Virtual Machine Manager Documentation