Set-SCVMHostCluster

Modifies the properties of a virtual machine host cluster managed by VMM.

Description

Modifies the properties of a host cluster managed by System Center Virtual Machine Manager (VMM). Properties that you can modify include changing the cluster reserve setting.

CLUSTER RESERVE
--------------------
The cluster reserve setting specifies the number of host failures that a host cluster can sustain before VMM considers the cluster to be over-committed. An over-committed host cluster is one that cannot withstand the specified number of host failures and still keep all of the virtual machines in the cluster running.

Virtual Machine Manager uses the following processes to determine over-commitment:

- Host Placement. The placement process calculates whether adding a new
  virtual machine to the host cluster will over-commit the host cluster
  and, if so, placement stops recommending the deployment of additional
  virtual machines on hosts in that cluster. 

- Cluster Refresher. The host cluster refresher calculates, at periodic 
  intervals, whether a host cluster is over-committed or not based on the
  following events:

  - A change in the value specified for the ClusterReserve parameter.
  - 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 following examples illustrate how over-commitment works:

- Example of over-commitment when all nodes are functioning: 

  If you specify a cluster reserve of 2 for an 8-node host cluster,
  and all 8 nodes are functioning, the host cluster is over-committed if
  any combination of 6 (8 minus 2) nodes lacks the capacity to accommodate 
  existing virtual machines.

- Example of over-commitment when some nodes are not functioning: 

  If you specify a cluster reserve of 2 for an 8-node host cluster, 
  but only 5 nodes are functioning, the host cluster is over-committed if
  any combination of 3 (5 minus 2) nodes lacks the capacity to accommodate 
  existing virtual machines.

For more information about Set-SCVMHostCluster, type: "Get-Help Set-SCVMHostCluster -online".

Parameters

VMHostCluster

Required? true
Accept Pipeline Input? true (ByValue)
Position? 0 
Specifies a VMM host cluster object.

ClusterReserve

Required? false
Accept Pipeline Input? false
Position? named 
Specifies the number of host failures that a host cluster can sustain before VMM designates the cluster as over-committed. The default value is 1.

Description

Required? false
Accept Pipeline Input? false
Position? named 
States a description for the specified object.

JobGroup

Required? false
Accept Pipeline Input? false
Position? named 
Specifies an identifier for a series of commands that will run as a set just before the final command that includes the same job group identifier runs.

JobVariable

Required? false
Accept Pipeline Input? false
Position? named 
Specifies that job progress is tracked and stored in the variable named by this parameter.

PROTipID

Required? false
Accept Pipeline Input? false
Position? named 
Specifies the ID of the PRO tip that triggered this action. This allows for auditing of PRO tips.

RunAsynchronously

Required? false
Accept Pipeline Input? false
Position? named 
Indicates that the job runs asynchronously so that control returns to the command shell immediately.

SetQuorumDisk

Required? false
Accept Pipeline Input? false
Position? named 
Specifies a disk to use as the quorum disk for the cluster.

SetQuorumNodeMajority

Required? false
Accept Pipeline Input? false
Position? named 
Sets the quorum mode to Node Majority for the cluster.

Examples

1: Change the setting for the cluster reserve for a host cluster. 
PS C:\> $VMHostCluster = Get-SCVMHostCluster -Name "VMHostCluster01.Contoso.com"
PS C:\> Set-SCVMHostCluster -VMHostCluster $VMHostCluster -ClusterReserve 2

The first commandgets the host cluster object named VMHostCluster01.Contoso.com and stores the object in the $VMHostCluster variable.

The second command changes value for the cluster reserve for host cluster VMHostCluster01 to 2.

See Also