HP XP P9000 Replication Manager Software 7.6.0-00 User Guide

• When creating a cascade configuration, it is necessary to first create a higher-level copy pair or
copy group. Higher-level copy pairs or copy groups cannot be added to lower-level copy pairs
or copy groups
• When creating a cascade configuration, copy types and pair statuses of related copy pairs or
copy groups must be compatible
• When deleting copy pairs or copy groups from a cascade configuration, you must first delete all
lower-level copy pairs or copy groups before deleting a higher-level copy pair or copy group
• The number of pairs that can be created varies depending on the storage system and copy type
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 170
• Limitations when performing 3DC configuration pair operations (mainframe systems), page 169
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.
2. To create a multi-target configuration, select a primary volume, and then click Add Group. To
create a cascade configuration, select a secondary volume, and then click Add Group.
3. For each pair group, define a list of copy pairs that you want to include in the pair group.
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