HP 3PAR Cluster Extension Software Installation Guide for Windows (5697-1822, March 2012)

1 Preparing to install HP 3PAR Cluster Extension
This chapter provides information about general environment considerations and pre-installation
requirements.
Ideal environment
The ideal configuration environment consists of at least five servers (two at each data center site
and one as an arbitrator at a third site) with separate, redundant communications links for cluster
heartbeats, client access, and a pair of HP 3PAR storage system with Remote Copy configuration.
All communications interfaces must be installed in pairs to serve as failover components, in order
to prevent single points of failure.
Network communication requirements
When using HP 3PAR Cluster Extension, note the following:
• Network communications links and components between the dispersed data centers must be
redundant and physically routed differently to prevent the “backhoe” issue that is created
when all links between data centers are cut together. This redundancy and routing is especially
important to prevent the split-brain syndrome that occurs when systems in both data centers
form new clusters and allow access to both copies of the data. Using redundant and separately
routed communication links and components, you can configure the failover behavior so that
the application service startup procedure stops if none of the remote cluster members can be
reached.
• Multi-pathing software must be used for host-to-storage connections.
Storage replication link requirements
To ensure reliable data backup between the local (primary) and remote (secondary) storage systems,
at least two HP 3PAR Remote Copy links must be available when the storage systems are connected
to provide redundancy and protection against single points of failure. Although communications
links can cover considerable distances, each network segment must be extended to the dispersed
data center to maintain a heartbeat among all servers. For extended distances, you must purchase
extender components to bundle the HP 3PAR Remote Copy links.
Server cluster infrastructure requirements
Use two cluster nodes at each site to give local application service failover procedures among
local cluster systems priority over remote, more time-consuming failover procedures. When failing
over, the software must reconfigure the storage systems to change the mirroring direction. At the
remote site, two systems should be available in case the primary failover system experiences a
hardware or power failure.
For windows, using a Majority Node Set (MNS) quorum requires an odd number of cluster nodes,
with at least one system in a third location. Where as, using a MNS with file share witness requires
even number of cluster nodes at each site with file share witness server at the third location.
CAUTION: HP 3PAR Cluster Extension works with one server at each location, with a single I/O
path between the server and storage system, and a single link between storage systems. However,
any configuration with a single point of failure is not considered highly available or disaster tolerant.
HP does not support configurations with single points of failure; configurations with one system at
each location are supported only if there are no single points of failure.
How HP 3PAR Cluster Extension Software interacts with its environment
This section describes the ways in which HP 3PAR Cluster Extension interacts with its environment.
Ideal environment 5