HP XP Continuous Access Software - Manual (Page 13)

Continuous Access XP user guide for the XP1024/XP128 13
1 Continuous Access XP for the XP1024/XP128
HP StorageWorks Continuous Access XP creates and maintains duplicate copies of user data from a local
disk array on a remote disk array. These copies are useful for data duplication, backup, and disaster
recovery. Continuous Access XP has synchronous and asynchronous copy modes to accommodate a wide
variety of user requirements and data copy or movement scenarios. Continuous Access XP is used for
open systems data.
If a system failure or disaster occurs at the primary (main) site, Continuous Access XP simplifies and
expedites disaster recovery procedures.
Continuous Access XP operations are nondisruptive and allow the primary (main) volume of each
Continuous Access XP volume pair to remain online to all hosts for read and write I/O operations. After
operations are established, Continuous Access XP operations continue unattended to provide continuous,
real-time data backup. Continuous Access XP operations can be performed across distances of up to 500
meters with a direct connection, 10 km (6.6 miles) using single-mode longwave optical fibre cables in a
switch configuration, 30 km (18.6 miles) using single-mode fiber with long-haul lasers in a switched
connection, and up to 100 km using DWDM in a switched configuration. For serial interface connection,
Continuous Access XP operations can be performed across distances of up to 43 km (26.7 miles) using
standard ESCON® support. Long-distance solutions are provided, based on user requirements and
workload characteristics, using approved channel extenders and communication lines.
Continuous Access XP operations can be performed with Business Copy XP operations (see ”
Overview of
Continuous Access XP operations ” on page 13) to provide multiple internal copies of Continuous Access
XP volumes. Continuous Access XP also supports LU Size Expansion (LUSE), Custom Volume Size (CVS),
and HP Cache LUN volumes. See ” Combining Continuous Access XP with other data management
operations ” on page 39 for more information.
Overview of Continuous Access XP operations
Continuous Access XP provides a storage-based hardware solution for disaster recovery, which enables
fast and accurate system recovery. After Continuous Access XP operations are established, duplicate
copies of data are automatically maintained for backup and disaster recovery purposes. During normal
Continuous Access XP operations, primary volumes remain online to all hosts and continue processing
read and write I/O operations. If a disaster or system failure occurs, the secondary copy of data can be
rapidly invoked to allow recovery with a very high level of data integrity. Continuous Access XP can also
be used for data duplication and migration tasks.
Continuous Access XP Synchronous provides volume-based real-time data replication and is ideal for
high-priority data backup, duplication, and migration tasks. If a disaster or system failure occurs at the
primary site, secondary Continuous Access XP Synchronous data can be rapidly invoked to allow
recovery at the volume level with an extremely high level of data integrity and currency. Up to a distance
of approximately 7-9 km, Continuous Access XP Synchronous provides the highest theoretical throughput.
Continuous Access XP Asynchronous represents a unique and outstanding disaster recovery solution for
large amounts of data spanning multiple volumes. The Continuous Access XP Asynchronous group-based
update sequence consistency solution enables fast and accurate database recovery after a disaster,
without time-consuming data recovery procedures. Continuous Access XP Asynchronous (Continuous
Access XP Async) volume groups at the remote site can be recovered with full update sequence
consistency, but data currency might be behind the primary site due to the asynchronous remote copy
operations.
Continuous Access XP Asynchronous provides update sequence consistency for user-defined groups of
volumes (such as large databases) and protection for write-dependent applications if a disaster occurs.
Beyond a distance of 7-9 km, Continuous Access XP Asynchronous provides the highest possible
theoretical throughput.
This overview of Continuous Access XP operations describes:
• ” Components ” on page 14
• ” Remote copy operations ” on page 19