Designating a Preferred Network for Cluster Shared Volumes Communication
Published: January 21, 2010
Updated: January 21, 2010
Applies To: Microsoft Hyper-V Server 2008 R2, Windows Server 2008 R2
In most cases, we recommend that you allow your failover cluster to automatically choose the network for Cluster Shared Volumes (CSV) communication. However, you can designate one or more preferred networks for CSV. This topic describes how to designate the most preferred network by setting the value for a cluster network property, Metric. For important information about requirements for the network for CSV, see Requirements for Using Cluster Shared Volumes in a Failover Cluster in Windows Server 2008 R2 in this guide.
When you enable Cluster Shared Volumes, the failover cluster automatically chooses the network that appears to be the best for CSV communication. However, you can designate the network by using the cluster network property, Metric. The lowest Metric value designates the network for CSV and internal cluster communication. The second lowest value designates the network for live migration, if live migration is used (you can also designate the network for live migration by using the failover cluster snap-in).
Another property, called AutoMetric, uses true and false values to track whether Metric is being controlled automatically by the cluster or has been manually defined.
When the cluster sets the Metric value automatically, it uses increments of 100. For networks that do not have a default gateway setting (private networks), it sets the value to 1000 or greater. For networks that have a default gateway setting, it sets the value to 10000 or greater. Therefore, for your preferred CSV network, choose a value lower than 1000, and give it the lowest metric value of all your networks.
To set the Metric value for a network, use the Windows PowerShell cmdlet Get-ClusterNetwork as described in the following procedure. For more information about the cmdlet, see Get-ClusterNetwork (http://go.microsoft.com/fwlink/?LinkId=143787).
On a node in the cluster, click Start, click Administrative Tools, and then click Windows PowerShell Modules. (If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Yes.)
To identify the networks used by a failover cluster and the properties of each network, type the following:
Get-ClusterNetwork | ft Name, Metric, AutoMetric, Role
A table of cluster networks and their properties appears (ft is the alias for the Format-Table cmdlet). For the Role property, 1 represents a private cluster network and 3 represents a mixed cluster network (public plus private).
To change the Metric setting to 900 for the network named Cluster Network 1, type the following:
( Get-ClusterNetwork "Cluster Network 1" ).Metric = 900
Note The AutoMetric setting changes from True to False after you manually change the Metric setting. This tells you that the cluster is not automatically assigning a Metric setting. If you want the cluster to start automatically assigning the Metric setting again for the network named Cluster Network 1, type the following:
( Get-ClusterNetwork "Cluster Network 1" ).AutoMetric = $true
To review the network properties, repeat step 2.