HP 3PAR Cluster Extension Software Administrator Guide for Windows (5697-1821, April 2012)

Fully Automatic Failover and Failback
Automated failover and failback reduces the complexity involved in a disaster recovery situation.
It is protection against the risk of downtime, whether planned or unplanned.
No server reboot
Disks on the server on both the primary and secondary sites are recognized during the initial system
boot in a HP 3PAR Cluster Extension environment; therefore LUN presentation and LUN mapping
changes are not necessary during failover or failback - for a truly hand-free disaster tolerant solution.
No single point of failure
Supreme redundancy: identical configuration of established SAN infrastructure redundancies are
implemented on remote site.
Synchronous replication mode support
HP 3PAR Remote Copy software offers synchronous data transfer mode between storage systems
and host. Synchronous data transfers offer the highest levels of data protection. With synchronous
operations, both the primary and secondary copies are identical and concurrent at all times.
Synchronous mirroring ensures that data copies are identical, to prevent critical data loss in the
event of a failure or disaster. In this mode, data is written simultaneously to the mirrored cache of
the primary storage system and the secondary storage system, in real time, before the application
I/O is completed, thus ensuring the highest possible data consistency. Synchronous replication is
appropriate when exact consistency is critical to the business application.
Asynchronous periodic replication mode support
HP 3PAR Remote Copy software offers asynchronous periodic data transfer replication mode
between the storage systems. In the asynchronous periodic mode, host writes are performed only
on the primary server. The host write is acknowledged as soon as the data is written into cache
on the primary storage server. The primary and backup volumes are re-synchronized periodically,
for example, when scheduled or when re-synchronization is manually initiated through the HP
3PAR CLI syncrcopy command.
NOTE: Currently, Asynchronous Periodic Replication Mode Support in CLX exists only on Windows
OS.
Storage system configurations
Cluster configurations typically consist of two or more server systems connected to a shared storage
system. HP 3PAR Cluster Extension allows the dispersion of data center resources by enabling
cluster systems to take advantage of HP 3PAR storage systems configured for Remote Copy
operations. HP 3PAR Cluster Extension uses HP 3PAR InForm OS Command Line Interface (CLI) to
control the HP 3PAR storage systems (and Remote Copy) with the cluster software, and uses cluster
software to react to system hardware and application failures.
HP 3PAR Cluster Extension behavior is based on four major considerations:
• Cluster software failover behaviors
• HP 3PAR Cluster Extension user settings
• The replication mode setting for HP 3PAR Remote Copy, which is used to configure the remote
replication feature of a 3PAR storage system environment based on your needs for application
service availability, data concurrency, and replication performance
• Remote Copy volume group and virtual volume status information
Fully Automatic Failover and Failback 9