Clusters and Load Balancing Requirements

When installing Exchange Server 2003 in a Windows 2003 clustered configuration, Exchange Server 2003 checks to determine whether the hardware and software prerequisites for installation are met. For a better understanding of the hardware and software requirements involved with installing Exchange Server 2003 in fault-tolerant environments, review the information provided in this section and ensure that the basic requirements are met before attempting to install the Exchange cluster.

Cluster Node Hardware Requirements

When determining the hardware requirements for a cluster server node, administrators must meet the same hardware requirements as are needed for installing Windows 2003 Advanced Server or Windows 2003 DataCenter Server. Each server node to be incorporated in the cluster must meet the minimum hardware requirements for installing the Windows server platform and must also be listed in the Cluster Service Hardware Compatibility List (HCL). To verify that the proposed hardware meets these requirements, go to http://www.microsoft.com/wwindowsserver2003/technologies/clustering/default.mspx.

When implementing fault-tolerant servers, hardware and hardware configurations on each server should be identical. For example, when installing PCI network cards, each card should be installed in the same slot on each server and have the same settings in the server's configuration properties. This minimizes configuration errors and troubleshooting confusion when the server is implemented as a node in the cluster.

When working with clustering, a single external disk storage cabinet is also required, which will be used to house the shared disks and quorum resource. It's best practice to configure these drives using a RAID level that provides fault tolerance.

The following are requirements for both nodes in the cluster:

• A local boot drive containing the Windows 2000 OS, which should be installed on a disk controller that is not connected to the shared storage

• Either a SCSI or Fiber Channel PCI host adapter connected to the shared storage

• Two PCI network adapters

Software Requirements

As mentioned earlier, Microsoft Windows 2003 cluster services require either Windows 2003 Enterprise Server or Windows 2003 DataCenter Server Editions. With the Enterprise Server Edition, support from 4-node clusters are provided as is with Windows with DataCenter ServerEdition.

Networking Requirements

Clusters with Windows Server 2003 require five static TCP/IP addresses to be dedicated to the cluster. Two TCP/IP addresses are used for the network adapters on the private network that control communication between the clustered Exchange server nodes, and an additional two are required for the network adapters on the public LAN. An additional IP address is used for the initial Windows 2003 cluster itself, which is the TCP/IP address to which clients connect.

NOTE

An additional IP address is required per Exchange virtual server on the Windows 2003 cluster. Running Exchange server in Active/Active mode requires two Exchange virtual servers. A 2-node Active/Active Exchange Server 2003 cluster requires a total of seven static TCP/IP addresses. For more information about Exchange 2003 virtual servers, review the section "Installing Exchange Server 2003 Clusters," later in this chapter.

As is with servers on the network, the Windows 2003 cluster also requires a NetBIOS name. This is the name that Exchange clients use to connect to the Exchange cluster and the cluster. In addition, each server node must also be configured as members in the same domain; however, they are not required to be members of the same domain from which clients are connecting.

CAUTION

When clustering with Exchange 2003 servers, each node must have two network adapters or NICs. When using clustered configurations like this, do not attempt to assign both the private and public TCP/IP addresses for the cluster nodes to the same network adapter. This configuration can cause instability in the cluster because of the possible disruption of the heartbeat communication between the clustered nodes, and is therefore unsupported by Microsoft technical support.

Shared Storage and Disks Requirements

Review the following information to understand the disk storage requirements, some best practice requirements, and some common best practices when working with clustered disk storage:

• All shared disks must be visible from both nodes. Check with the hardware vendor for known issues when using disk subsystem hardware in fault-tolerant environments and always install the latest BIOS revisions and support packs before setting up the cluster. Getting both servers to recognize the shared storage is usually the trickiest part of configuring the cluster.

• Any logical disk in the shared storage system must be configured as a Windows 2003 basic disk. Do not configure a dynamic disk in shared storage systems.

• All disk partitions used in the storage system must be formatted as NTFS.

• As best practice, use hardware-based fault-tolerant RAID sets on physical drive configurations to optimize performance and redundancy.

• Separate transaction logs and databases. Use hardware RAID 1 or 0+1 for the Exchange Server transaction log drives and RAID 5 or 0+1 for database storage.

• When creating the drive arrays on the shared storage device, be sure to create logical partitions in the RAID drive array utility so that Windows will see more than one hard drive. Five logical drives is usually optimum, to provide one drive for the quorum resource and two drives for each Exchange virtual server. Use one Exchange virtual server drive for the databases and the other for the transaction logs.