HP XP Continuous Access Software - Manual (Page 11)

2 About XP Continuous Access Journal Operations
This chapter describes how XP Continuous Access Journal provides a storage-based, XP hardware
solution for disaster recovery that enables fast and accurate system recovery. Once XP Continuous
Access Journal operations are established, duplicate copies of data are automatically maintained
for backup and disaster recovery purposes:
•
“Functionality Overview” (page 11)
•
“XP Continuous Access Journal Components” (page 13)
•
“XP Continuous Access Journal Remote Copy Operations” (page 21)
•
“Journal Processing” (page 25)
•
“Pair Status” (page 32)
XP Continuous Access Journal is a disaster recovery solution for protecting large amounts of data
that span multiple volumes. XP Continuous Access Journal is a solution that uses group-based,
update sequence consistency to enable fast and accurate database recovery even after a rolling
disaster, while it avoids the need for time-consuming data recovery procedures. User-defined XP
Continuous Access Journal groups (volume groups) at the secondary site can be recovered with
full update sequence consistency due to asynchronous copy operations. This functionality also
provides protection for write-dependent applications in the event of a disaster.
Functionality Overview
XP Continuous Access Journal enables you to create duplicate volumes by copying data from the
primary data volumes in the primary storage system to the secondary data volumes in the secondary
storage system at the remote location. To create duplicate volumes, use the following functions:
•
Use the journal obtain function at the primary site.
•
Use the journal copy function between the primary and secondary sites.
•
Use the journal restore function at the secondary site.
These functions are performed sequentially between the primary and secondary data volumes and
the journal volumes.
Write sequence consistency for the primary data volume at the primary site is similarly maintained
for the secondary data volume at the secondary site through the use of the write sequence number
assigned to the journal data by the journal obtaining function. The use of the write sequence number
enables you to configure the duplicate system with assurance of data integrity.
XP Continuous Access Journal reduces the occurrence of pair suspensions, due to data transfer
restrictions from the primary site to the secondary site, by storing write data from the host in the
master and restore journal volumes. This action provides a highly-reliable duplication system.
Figure 1 (page 12) shows an overview of XP Continuous Access Journal operations for a Fibre
Channel connection.
Functionality Overview 11