HP XP Continuous Access Software - Manual (Page 78)

data volume, asynchronously with regards to writing from the host. Update sequence consistency is
maintained with the Continuous Access XP Journal secondary data volume.
Because writing from the Continuous Access XP Journal primary volume to the Continuous Access XP
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 Continuous
Access XP Journal primary and secondary sites are far from each other.
In addition, you can create a Continuous Access XP Journal pair for delta resync operations in 3DC
multi-target configurations by specifying:
• A Continuous Access XP Synchronous S-VOL in the Continuous Access XP Synchronous secondary
site as the Continuous Access XP Journal delta resync primary data volume
• The volume in the Continuous Access XP Journal secondary site as the Continuous Access XP
Journal delta secondary data volume
If you create a Continuous Access XP Journal pair for delta resync operations, you can resynchronize
the Continuous Access XP Journal pair using journal data already residing in the Continuous Access XP
Synchronous secondary site when a failure occurs in the primary site.
For more information about the hardware configuration required for 3DC multi-target configuration, see
Hardware configurations . For more information about the requirements to create a Continuous Access
XP Journal pair for delta resync operation, see Requirements for creating Continuous Access XP Journal
pairs for delta resync operations . For more information about the requirements to perform delta resync
operation, see Requirements for performing delta resync operations .
If a failure occurs in a Continuous Access XP Synchronous primary volume, which is also used as a
Continuous Access XP Journal primary data volume, you can resume your business tasks using the
Continuous Access XP Synchronous secondary volume. After resuming your business tasks, remove the
failure from the primary volume and transfer your business tasks back to the primary site. For more
information, see the following:
• Recovering from primary site failures
• Recovering from primary site failures (when performing delta resync operations)
• Changing to 3DC multi-target configurations after recovering from primary site failures
• Transferring business tasks from Continuous Access XP secondary sites to primary sites (in 3DC
cascading configurations)
• Transferring business tasks from Continuous Access XP secondary sites to primary sites (in 3DC
multi-target configurations)
• Transferring business tasks from Continuous Access XP secondary sites to primary sites (when
performing delta resync operations in 3DC multi-target configurations)
If a failure occurs in the primary volume and Continuous Access XP Synchronous secondary volume, you
can resume your business tasks using the Continuous Access XP Journal secondary data volume. After
resuming the your business tasks, remove the failure from the primary volume and Continuous Access
XP Synchronous secondary volume, and transfer your business tasks back to the primary site. For more
information, see Recovering from primary site and Continuous Access XP Synchronous secondary site
failures and Transferring business tasks from Continuous Access XP Journal secondary sites to primary
sites .
Hardware configurations
A 3DC multi-target configuration requires the following sites:
• Primary site for Continuous Access XP Synchronous and Continuous Access XP Journal
• Secondary site for Continuous Access XP Synchronous
• Secondary site for Continuous Access XP Journal
Each site requires one local array. For Command View XP, a management station is also required.
HP recommends installing RAID Manager XP in the host computers at each site.
The following hardware configuration is required for the local array at these sites:
78 Continuous Access XP Journal operations requirements and restrictions