HP XP Continuous Access Software User Manual
Page 70
combined, there are one primary and two secondary sites. One secondary site is for synchronous
remote copy, and is usually located a short distance from the primary site. The other secondary
site is for asynchronous remote copy, and is usually located a long distance from the primary site.
This system configuration is called a three data center (3DC) multi-target configuration.
A 3DC multi-target configuration provides a solution for disaster recovery and business continuity.
Even when a disaster or failure occurs at two sites at the same time, you can restart your business
tasks using data in the remaining secondary site.
illustrates a 3DC multi-target configuration where XP Continuous Access
Journal and XP Continuous Access Synchronous are combined. This configuration consists of the
following sites:
•
Primary site for XP Continuous Access Synchronous and XP Continuous Access Journal (DC1
- data center 1)
•
Secondary site for XP Continuous Access Synchronous (DC2- data center 2)
•
Secondary site for XP Continuous Access Journal (DC3- data center 3)
Figure 31 3DC multi-target configuration (combining XP Continuous Access Journal with XP
Continuous Access Synchronous)
In this configuration, the primary volume at the primary site is paired with the secondary volume
for XP Continuous Access Synchronous. This primary volume is also paired with the secondary
volume for XP Continuous Access Journal. If a host at the primary site writes data to the primary
volume, the data is written to the XP Continuous Access Synchronous secondary volume in real
time, synchronously with regards to writing from the host. The data is also written to the XP
Continuous Access Journal secondary data volume, asynchronously with regards to writing from
the host. Update sequence consistency is maintained with the XP Continuous Access Journal
secondary data volume.
Because writing from the XP Continuous Access Journal primary volume to the XP Continuous Access
Journal secondary volume is performed asynchronously with regards to writing from the host to
the primary volume, this configuration prevents delays in the response to the host even if the XP
Continuous Access Journal primary and secondary sites are far from each other.
70
XP Continuous Access Journal operations requirements and restrictions