HP P6000 Cluster Extension Software Administrator Guide (5697-0986, June 2011)

One-to-one configuration
When setting up a one-to-one configuration (see Figure 2 on page 18), consider the following:
• Cluster host nodes are split between two or more geographically dispersed data center sites and
use redundant, diversely routed network connections for intra-cluster communications. Those links
must be as reliable as possible to prevent false failover operations or split-brain situations.
• Each cluster host node connected to a P6000/EVA storage system should have redundant I/O
paths to the P6000/EVA storage system. Connections to both the source (primary) and the destin-
ation (secondary) copy of the application disk set are not allowed from the same host. Configure
your servers only in the zone that allows access to the local P6000/EVA storage system.
• HP recommends a minimum of two cluster host nodes per site. This allows for preferred local failover
in case of system failure. Local failover operations are faster than remote failover between
P6000/EVA storage systems because you do not need to change the mirroring direction of the
DR group members.
• You can deploy P6000 Cluster Extension in environments where several clusters use the same
P6000/EVA storage system pair.
• You can use P6000 Continuous Access in synchronous replication mode with P6000 Continuous
Access between two P6000/EVA storage systems connected using FC switches and extender
hardware.
• You can use P6000 Continuous Access in enhanced asynchronous mode with P6000 Cluster Ex-
tension 4.00.01 and later for Windows.
NOTE:
For complete information on which write modes are supported on each version of controller
software, see the HP Enterprise Virtual Array Compatibility Reference .
• P6000 Cluster Extension supports P6000 Continuous Access in synchronous replication mode and
enhanced asynchronous replication mode in the following configurations:
• Switched FC connection (dual-fabric intersite links)
• FC to DWDM networks, via FC switches
• FC over IP networks, via FC switches as shown in the HP P6000 Continuous Access Implement-
ation Guide
• The P6000 Continuous Access links must have redundant, separately routed links for each fabric.
The cluster network must have redundant, separately routed links. However, cluster networks and
P6000 Continuous Access can share the same links if the link technology is protocol independent
(for example, WDM) or if the FC protocol is transformed into IP.
HP P6000 Cluster Extension Software Administrator Guide 17