There are specific hardware and software requirements that you must address before implementing virtual host clustering. Each host requires two network adapters (this does not include any adapters required for iSCSI). One network adapter is used to connect a node to the public network (client-to-cluster communication). The second adapter is used to connect a cluster node to the private network (node-to-node communication).

One of the requirements of Cluster Service is a shared disk that all nodes in a cluster are connected to. Cluster Service cannot use the storage device and controller that services the Windows installation. Therefore, each host must meet one of the following two requirements:

• If using SCSI or Fibre Channel, each node in the cluster requires a minimum of two disk controllers. One of the controllers must be dedicated to the cluster storage.
• If using iSCSI, each host requires a network adapter or host bus adapter that is dedicated to the cluster storage.

Each node in the cluster requires a private disk for the installation of Windows. Between the cluster nodes, there must also be at least one shared disk. If this disk is not present, the installation of Cluster Service will fail. The shared disk will host the virtual disks, thereby increasing their availability. If one node fails, the other node can take control of the shared disk and continue to run the guest operating systems.

Note: It is recommended that the shared disk have at least two volumes - one for the quorum resource and the other for the virtual disk. If possible, though, the Quorum resource should be placed on a separate shared disk.
Not all versions of Windows Server 2003 include Cluster Service. If you plan to use virtual host clustering you will need to install one of the following versions of Windows Server 2003 on your hosts:

• Windows Server 2003 SP1, Enterprise Edition
• Windows Server 2003 SP1, Datacenter Edition
• Windows Server 2003 R2, Enterprise Edition
• Windows Server 2003 R2, Datacenter Edition

Tip: Be sure to install Internet Information Services (IIS) on the computer from which you plan to manage your virtual servers. IIS is required to install the Virtual Server management tool.

Each host in the cluster must also be running Virtual Server 2005 R2. This version of Virtual Server supports iSCSI for use in a server cluster. There is also a script that you can run to ensure that your guest operating systems function correctly within a cluster environment.

If you decide to use iSCSI technology, you need to install the Microsoft iSCSI Software Initiator 2.0 or higher. This is available as a free download on the Microsoft Web site.

As I mentioned above, a script is available from Microsoft that ensures your guest operating systems function correctly within a clustered environment. To use the script, copy the script text (available on Microsoft’s Web site) to into Notepad and save it as Havm.vbs. The script must be copied and executed on each host.

[tags]active directory server, virtual server 2005 r2, clustering server[/tags]