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Requirements for Using Cluster Shared Volumes in a Failover Cluster in Windows Server 2008 R2

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Updated: January 21, 2010

Applies To: Microsoft Hyper-V Server 2008 R2, Windows Server 2008 R2

This topic lists the requirements for using Cluster Shared Volumes (CSV) in a failover cluster running Windows Server 2008 R2 or Hyper-V Server 2008 R2. For additional important information about requirements, see the topics listed in Additional references.

Network requirements for using Cluster Shared Volumes

If you are using Cluster Shared Volumes, your network configuration must meet the following requirements:

  • Network adapters. We recommend that you install enough network adapters in each node so that one network is available for CSV while other networks are available for other purposes. For more information, see Understanding redirected I/O mode in CSV communication later in this topic. We recommend that you do not use the same network adapter for CSV communication as you use for virtual machine access and management.

    We recommend that you allow your failover cluster to automatically choose the network for CSV communication. However, you can designate one or more preferred networks for CSV. For more information, see Designating a Preferred Network for Cluster Shared Volumes Communication in this guide.

  • Network adapter properties. In the properties for all adapters that carry cluster communication, make sure that Client for Microsoft Networks and File and Printer Sharing for Microsoft Networks are enabled to support Server Message Block (SMB), which is required for CSV. (Because the server is running Windows Server 2008 R2, it automatically provides the version of SMB that is required by CSV, which is SMB2.) Only one network will be the preferred network for CSV communication, but enabling these settings on multiple networks helps the cluster respond to failures.

    If the cluster nodes are connected to networks that should not be used by the cluster, in Failover Cluster Manager, in the properties for each of those networks, select Do not allow cluster network communication on this network.

  • IP subnet configuration. For each network in a failover cluster where Cluster Shared Volumes is enabled, all nodes must be on the same logical subnet, which means that multisite clusters that use Cluster Shared Volumes must use a VLAN.

For storage network recommendations, review the guidelines that are provided by your storage vendor.

Understanding redirected I/O mode in CSV communication

Usually, when the cluster node that owns a virtual hard disk (VHD) file in CSV performs disk input/output (I/O), the node communicates directly with the storage, for example, through a storage area network (SAN). However, storage connectivity failures sometimes prevent a given node from communicating directly with the storage. To maintain function until the failure is corrected, the node redirects the disk I/O through a cluster network (the preferred network for CSV) to the node where the disk is currently mounted. This is called CSV redirected I/O mode.

To see the mode of a given CSV disk, in Failover Cluster Manager, look at any display that shows the disk (for example, the Storage display). To determine which cluster node lost connectivity with a CSV disk, in Failover Cluster Manager, click Cluster Events, and look for event 5121.

A disk in CSV is also placed into redirected I/O mode during management operating-system based backups, also known as parent-partition based backups. (For a description of management operating-system based backups, see Backing Up Cluster Shared Volumes in a Failover Cluster in Windows Server 2008 R2 in this guide.)

When a disk in CSV is in redirected I/O mode, the network that is used for CSV communication might need to carry significantly heavier network traffic. The possibility of heavier network traffic is one reason why we recommend that you install enough network adapters in each node so that one network is available for CSV while other networks are available for other purposes.

Storage and disk configuration requirements for using Cluster Shared Volumes

If you are using Cluster Shared Volumes, your configuration settings related to storage and disks must meet the following requirements:

  • Resource type in the cluster. For CSV, you must use the Physical Disk resource type.

  • Choice of CSV disks or other disks in cluster storage. When choosing one or more disks for a clustered virtual machine, you must consider how each disk will be used. If a disk will be used to store files created by Hyper-V, such as virtual hard disk (VHD) files or configuration files, you can choose either from the CSV disks or the other available disks in cluster storage. If a disk will be a physical disk that is directly attached to the virtual machine (also called a pass-through disk), you cannot choose a CSV disk, but must instead choose from the other available disks in cluster storage.

  • Path name for identifying disks. Disks in CSV are identified with a path name. The path appears to be on the system drive of the node as folders under the \ClusterStorage folder, although this path is the same when viewed from any node in the cluster. Disks in CSV do not use drive letters or mount points. (A disk in CSV might sometimes be identified by a GUID within the context of a backup solution, but it will still use a path name in the context of the failover cluster snap-in.)

For storage requirements for Cluster Shared Volumes, review the guidelines that are provided by your storage vendor.

Node requirements for using Cluster Shared Volumes

If you are using Cluster Shared Volumes, your nodes (servers) must meet the following requirements:

  • Operating system. All nodes must run Windows Server 2008 R2 or Hyper-V Server 2008 R2. All nodes must run the same operating system, except that you can combine nodes running Hyper-V Server 2008 R2 in the same cluster with nodes running the Server Core installation of Windows Server 2008 R2.

  • Drive letter of system disk. On all nodes, the drive letter for the system disk must be the same.

  • Authentication protocol. The NTLM protocol must be enabled on all nodes.

  • Hyper-V role. The Hyper-V server role must be added on any cluster node that runs Windows Server 2008 R2 and might host a virtual machine.

Additional references