HP XP Cluster Extension Software Administrator Guide

replication performance. XP Cluster Extension supports all Continuous Access fence levels: NEVER,
DATA, and JOURNAL.
XP Cluster Extension is supported with the Continuous Access Software in the configurations
described in the HP SAN Design Reference Guide Volume 1 to 5, available at http://www.hp.com/
go/sdgmanuals.
XP Cluster Extension server configurations
The ideal cluster configuration for XP Cluster Extension consists of at least four servers (two at each
site) and separate redundant communications links for cluster heartbeats, client access, and the
Continuous Access Software. Installing communications interfaces in pairs allows failover and
prevents single points of failure (SPOFs). Using four servers provides faster recovery from a system
failure by allowing local application services to fail over to a local cluster system instead of the
remote system. On the remote site, HP recommends that two systems be available in case one
system experiences a hardware or power failure. In addition to at least four servers, the Node
Majority quorum configuration requires an additional node per cluster, located at a third site so
that whenever a disaster affects either the local or remote site, the other site together with the added
node would have a majority. In a Node Majority quorum with File Share Witness configuration,
the, file share should be located at the third site.
XP Cluster Extension allows you to configure the failover behavior so that the application service
startup is stopped if no remote cluster members can be reached. The default configuration of XP
Cluster Extension expects the cluster software to deal with the split-brain syndrome.
Planning for XP Cluster Extension
Before configuring XP Cluster Extension resources
Before configuring XP Cluster Extension resources for the CLI implementation , review the XP Cluster
Extension objects in the UCF.cfg file. For more information about XP Cluster Extension objects,
see “User configuration file and XP Cluster Extension objects” (page 47).
Cluster setup considerations
For cluster setup considerations, see below.
Node Majority quorum clusters (MSFC)
In an Node Majority quorum cluster, the cluster service is allowed to start or run only if it has access
to the majority of the configured nodes.
This means that losing half the nodes in a 2-, 4-, 6-, or 8-node cluster or losing the communication
links with 50% of the nodes on each site forces every node to terminate the cluster services because
none of them have access to a majority of the configured nodes.
Therefore, a geographically dispersed Node Majority quorum-based cluster requires an additional
node per cluster located at a third site so that whenever a disaster affects either the local or remote
site, the other site together with the added node has a majority.
NOTE: HP XP Cluster Extension does not support quorum configuration which includes disk
witness. Please see Microsoft documentation for more details on quorum configuration.
Setting up RAID Manager
In addition to the cluster software it integrates with, XP Cluster Extension depends on RAID Manager.
Before configuring XP Cluster Extension, verify that RAID Manager is installed and configured, and
that the host and disk array systems are properly configured as described in the following topics.
Planning for XP Cluster Extension 9