HP XP P9000 Command View Advanced Edition Software - Manual (Page 163)

Alternative configuration to im-
plement requirement
Requirement for configuration Unsupported configuration
Create CTGs in the cascade source
according to the cascade destina-
tion copy groups. Pairs in the cas-
cade source must belong to any
CTG.
To create a backup of only some
volumes. The cascade destination contains
multiple copy groups.
Legend:
*: When primary volumes and secondary volumes in the same copy group belong to different storage
systems, it is necessary to create CTGs with volumes that have the same combination of primary and
secondary storage systems.
About delta resync
In a 3DC multi-target configuration, there is one primary site and two secondary sites. Continuous
Access Synchronous and Continuous Access Journal are used to copy storage system volumes among
the three sites (called a data center). Continuous Access Journal provides the primary site and
Continuous Access Synchronous and Continuous Access Journal provide the secondary sites. Replication
Manager can be used to configure a Delta Resync pair using the two secondary sites. Delta Resync
pairs are stand-by pairs for providing additional redundancy in 3DC multi-target configurations.
Continuous Access Journal provides the delta resync operation as a way to recover from failures in
the primary site. If a failure occurs at the primary site in a 3DC multi-target configuration, the P9000
RAID Manager
horctakeover command is used to reconfigure the Continuous Access Synchronous
secondary site as the primary site. If the delta re-synchronization function is used between the primary
and secondary sites, journal-copying of only the minimum data required is performed following a
failure, minimizing the recovery time.
Related topics
• Creating a 3DC multi-target configuration , page 164
• Limitations when performing 3DC configuration pair operations (mainframe systems) , page 163
Limitations when performing 3DC configuration pair operations (mainframe systems)
The following limitations and resolutions are to be noted when performing 3DC configuration pair
operations:
• When operating Delta Resync, it is necessary to switch the direction of Continuous Access Syn-
chronous in advance. Because Replication Manager does not switch the direction automatically,
it is necessary to switch the direction manually.
• The Force option cannot be added when executing Delta Resync.
• Delta Resync can be executed for copy groups only. It cannot be executed for CTGs or copy pairs.
• If a related Cnt Ac-J is deleted, the DeltaUR pair transitions to Simplex status. However the DeltaUR
pair information is not updated in Replication Manager. The DeltaUR pair information will be
deleted when a configuration update is performed. To resolve this, it is first necessary to delete
the DeltaUR and then delete the related Cnt Ac-J pair.
Defining copy groups in a multi-target or cascade configuration
To define copy groups in a multi-target or cascade configuration:
1. Perform the pair group registration operations.
User Guide 163