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• If possible, have all hosts on the same subnet, and then connect them to an iso-
lated switch or configure them to connect in a single VLAN if you have that
• Disable the source MAC masking feature in the Registry. The source MAC
masking feature is used to change the MAC address of traffic originating from
the cluster from the individual cluster node’s MAC address to the MAC address
of the server. In multicast mode in switching environments, this can flood
switching ports, so disabling this feature will work around that problem. Change
the Registry value of:
from 1 to 0. Restart all mllembers of the cluster after making this change.
If an NLB cluster is too limited in functionality for you, you should investigate a true
server cluster. In a true server cluster, a group of machines have a single identity and
work in tandem to manage and, in the event of failure, migrate applications away
from problematic nodes and onto functional nodes. The nodes of the cluster use a
common, shared resource database and log storage facility provided by a physical
storage device that is located on a hardware bus shared by all members of the cluster.
The shared data facility does not support IDE disks, software RAID
(including Windows-based dynamic RAID), dynamic disks or vol-
umes, the EFS, mounted volumes and reparse points, or remote stor-
age devices such as tape backup drives.
Three types of clusters are supported by Windows Server 2003 in the Enterprise and
Datacenter editions of the product: single node clusters, which are useful in test and
laboratory environments to see if applications and resources function in the manner
intended but do not have any sort of fault-tolerant functionality; single quorum
device clusters, which are the most common and most functional type of cluster used
in production because of their multiple nodes; and majority node set clusters, which
function as a cluster but without a shared physical storage device, something
required of the other two types. Majority node set clusters are useful if you do not
have a SCSI-based SAN or if the members of a cluster are spread out over several dif-
ferent sites, making a shared storage bus unfeasible. The Enterprise Edition supports
up to four cluster nodes; the Datacenter Edition supports up to eight.